Science.gov

Sample records for air circulation patterns

  1. Natural Circulation Patterns in the VHTR Air-Ingress Accident and Related Issues

    SciTech Connect

    Chang H. Oh; Eung S. Kim

    2012-08-01

    Natural circulation patterns in the VHTR during a hypothetical air-ingress accident have been investigated using computational fluid dynamic (CFD) methods in order to compare results from the previous 1-D model which was developed using GAMMA code for the air-ingress analyses. The GT-MHR 600 MWt reactor was selected to be the reference design and modeled by a half symmetric 3-D geometry using FLUENT 6.3, a commercial CFD code. CFD simulations were carried out as the steady-state calculation, and the boundary conditions were either assumed or provided from the 1-D GAMMA code results. Totally, 12 different cases have been reviewed, and many notable results have been obtained through in this work. According to the simulations, natural circulation patterns in the reactor were quite different from the previous 1-D assumptions. A large re-circulation flow with thermal stratification phenomena was clearly observed in the hot-leg and the lower plenum in the 3-D model. This re-circulation flow provided about an order faster air-ingress speed (0.46 m/s in superficial velocity) than previously predicted by 1-D modeling (0.02~0.03 m/s). It indicates that the 1-D air-ingress modeling may significantly distort the air-ingress scenario and consequences. In addition, complicated natural circulation patterns are eventually expected to result in very complex graphite oxidations and corrosion behaviors.

  2. Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Böhme, M.

    2004-05-01

    The migration history of an air-breathing fish group (Channidae; snakehead fishes) is used for reconstructing Neogene Eurasian precipitation and atmospheric circulation patterns. The study shows that snakeheads are sensitive indicators of summer precipitation maxima in subtropical and temperate regions, and are present regularly if the wettest month exceeds 150 mm precipitation and 20 °C mean temperature. The analysis of 515 fossil freshwater fish deposits of the past 50 m.y. from Africa and Eurasia shows two continental-scale migration events from the snakeheads' center of origin in the south Himalayan region, events that can be related to changes in the Northern Hemisphere circulation pattern. The first migration, ca. 17.5 Ma, into western and central Eurasia may have been caused by a northward shift of the Intertropical Convergence Zone that brought western Eurasia under the influence of trade winds that produced a zonal and meridional precipitation gradient in Europe. During the second migration, between 8 and 4 Ma, into Africa and East Asia, snakeheads reached their present-day distribution. This migration could have been related to the intensification of the Asian monsoon that brought summer precipitation to their migratory pathways in East Africa Arabia and East Asia.

  3. Portable oven air circulator

    DOEpatents

    Jorgensen, Jorgen A.; Nygren, Donald W.

    1983-01-01

    A portable air circulating apparatus for use in cooking ovens which is used to create air currents in the oven which transfer heat to cooking foodstuffs to promote more rapid and more uniform cooking or baking, the apparatus including a motor, fan blade and housing of metallic materials selected from a class of heat resistant materials.

  4. The impact of circulation patterns on regional transport pathways and air quality over Beijing and its surroundings

    NASA Astrophysics Data System (ADS)

    Zhang, J. P.; Zhu, T.; Zhang, Q. H.; Li, C. C.; Shu, H. L.; Ying, Y.; Dai, Z. P.; Wang, X.; Liu, X. Y.; Liang, A. M.; Shen, H. X.; Yi, B. Q.

    2012-06-01

    This study investigated the air pollution characteristics of synoptic-scale circulation in the Beijing megacity, and provided quantitative evaluation of the impacts of circulation patterns on air quality during the 2008 Beijing Summer Olympics. Nine weather circulation types (CTs) were objectively identified over the North China region during 2000-2009, using obliquely rotated T-mode principal component analysis (PCA). The resulting CTs were examined in relation to the local meteorology, regional transport pathways, and air quality parameters, respectively. The FLEXPART-WRF model was used to calculate 48-h backward plume trajectories for each CT. Each CT was characterized with distinct local meteorology and air mass origin. CT 1 (high pressure to the west with a strong pressure gradient) was characterized by a northwestern air mass origin, with the smallest local and southeasterly air mass sources, and CT 6 (high pressure to the northwest) had air mass sources mostly from the north and east. On the contrary, CTs 5, 8, and 9 (weak pressure field, high pressure to the east, and low pressure to the northwest, respectively) were characterized by southern and southeastern trajectories, which indicated a greater influence of high pollutant emission sources. In turn, poor air quality in Beijing (high loadings of PM10, BC, SO2, NO2, NOx, O3, AOD, and low visibility) was associated with these CTs. Good air quality in Beijing was associated with CTs 1 and 6. The average visibilities (with ±1σ) in Beijing for CTs 1 and 6 during 2000-2009 were 18.5 ± 8.3 km and 14.3 ± 8.5 km, respectively. In contrast, low visibility values of 6.0 ± 3.5 km, 6.6 ± 3.7 km, and 6.7 ± 3.6 km were found in CTs 5, 8, and 9, respectively. The mean concentrations of PM10 for CTs 1, 6, 5, 8, and 9 during 2005-2009 were 90.3 ± 76.3 μg m-3, 111.7 ± 89.6 μg m-3, 173.4 ± 105.8 μg m-3, 158.4 ± 90.0 μg m-3, and 151.2 ± 93.1 μg m-3, respectively. Analysis of the relationship between

  5. The impact of circulation patterns on regional transport pathways and air quality over Beijing and its surroundings

    NASA Astrophysics Data System (ADS)

    Zhang, J. P.; Zhu, T.; Zhang, Q. H.; Li, C. C.; Shu, H. L.; Ying, Y.; Dai, Z. P.; Liu, X. Y.; Liang, A. M.; Shen, H. X.

    2011-12-01

    This study investigated the air pollution characteristics of synoptic-scale circulation in the Beijing megacity, and provided holistic evaluation of the impacts of circulation patterns on air quality during the 2008 Beijing Summer Olympics. Nine weather circulation types (CTs) were objectively identified over the North China region during 2000-2009, using obliquely rotated T-mode principal component analysis (PCA). The resulting CTs were examined in relation to the local meteorology, regional transport pathways, and air quality parameters, respectively. The FLEXPART-WRF model was used to calculate 48-h backward plume trajectories for each CT. Nine CTs were characterized, with distinct local meteorology and air mass origins. CT 1 (high to the west with a strong pressure gradient) was characterized by a northwestern origin, with the smallest local and southeasterly air mass sources, and CT 6 (high to the northwest) had air mass sources mostly from the north and east. In contrast, CTs 5, 8, and 9 (unique, high to the east, and low to the northwest, respectively) were characterized by southern and southeastern trajectories, which indicated a greater influence of high pollutant emission sources. In turn, poor air quality in Beijing (high loadings of PM10, BC, SO2, NO2, O3, AOD, and low visibility) was associated with these CTs. Good air quality in Beijing was associated with CTs 1 and 6. The average visibilities (with ±1 σ) in Beijing for CTs 1 and 6 during 2000-2009 were 18.5 ± 8.3 km and 14.3 ± 8.5 km, respectively. In contrast, poor visibility values of 6.0 ± 3.5 km, 6.6 ± 3.7 km, and 6.7 ± 3.6 km were found in CTs 5, 8, and 9, respectively. The mean concentrations of PM10 for CTs 1, 6, 5, 8, and 9 during 2005-2009 were 90.3 ± 76.3 μg m-3, 111.7 ± 89.6 μg m-3, 173.4 ± 105.8 μg m-3, 158.4 ± 90.0 μg m-3, and 151.2 ± 93.1 μg m-3, respectively. Analysis of the relationship between circulation pattern and air quality during the emission control period

  6. Fluoride pollution of atmospheric precipitation and its relationship with air circulation and weather patterns (Wielkopolski National Park, Poland).

    PubMed

    Walna, Barbara; Kurzyca, Iwona; Bednorz, Ewa; Kolendowicz, Leszek

    2013-07-01

    A 2-year study (2010-2011) of fluorides in atmospheric precipitation in the open area and in throughfall in Wielkopolski National Park (west-central Poland) showed their high concentrations, reaching a maximum value of 2 mg/l under the tree crowns. These high values indicate substantial deposition of up to 52 mg/m(2)/year. In 2011, over 51% of open area precipitation was characterized by fluoride concentration higher than 0.10 mg/l, and in throughfall such concentrations were found in more than 86% of events. In 2010, a strong connection was evident between fluoride and acid-forming ions, and in 2011, a correlation between phosphate and nitrite ions was seen. Analysis of available data on F(-) concentrations in the air did not show an unequivocal effect on F(-) concentrations in precipitation. To find reasons for and source areas of high fluoride pollution, the cases of extreme fluoride concentration in rainwater were related to atmospheric circulation and weather patterns. Weather conditions on days of extreme pollution were determined by movement of weather fronts over western Poland, or by small cyclonic centers with meteorological fronts. Macroscale air advection over the sampling site originated in the western quadrant (NW, W, and SW), particularly in the middle layers of the troposphere (2,500-5,000 m a.s.l.). Such directions indicate western Poland and Germany as possible sources of the pollution. At the same time in the lower troposphere, air inflow was frequently from the north, showing short distance transport from local emitters, and from the agglomeration of Poznań. PMID:23114919

  7. Circulation pattern classification for climate change studies

    NASA Astrophysics Data System (ADS)

    Stehlik, J.; Bardossy, A.

    2003-04-01

    Several circulation pattern classifications developed for different European regions were compared regarding their mutual dependence. Circulation pattern (CP) classifications, both subjective and objective, for the British Isles, Germany and Greece were taken into account. Statistical tests were applied in order to investigate the relationships between each pair of CP classifications. It was found that each pair of classifications can not be considered to be independent. Time dependence of the relationship between CP classifications shows anomaleous behavior only when one of the classifications is subjective. This can be due to a gradual change in the methodology. Thus, one should use these classifications for climate evolution studies with care. Results showing the inter-dependence of different CP classifications were motivation for developing one classification which would be valid in every European region. For this purpose an objective and automated classification was applied. By means of daily 700 hPa data, 13 CPs were defined which explain the variability of local precipitation in 27 stations spread over the whole of Europe. The validation of this classification proved that there is almost no information lost when comparing this classification with local classifications. Based on this classification method the air pressure outputs from Global Circulation Models will be classified. Subsequently the classified circulation patterns will be used for climate change studies. For this purpose statistical downscaling of precipitation will be applied.

  8. SpaceX Dragon Air Circulation System

    NASA Technical Reports Server (NTRS)

    Hernandez, Brenda; Piatrovich, Siarhei; Prina, Mauro

    2011-01-01

    The Dragon capsule is a reusable vehicle being developed by Space Exploration Technologies (SpaceX) that will provide commercial cargo transportation to the International Space Station (ISS). Dragon is designed to be a habitable module while it is berthed to ISS. As such, the Dragon Environmental Control System (ECS) consists of pressure control and pressure equalization, air sampling, fire detection, illumination, and an air circulation system. The air circulation system prevents pockets of stagnant air in Dragon that can be hazardous to the ISS crew. In addition, through the inter-module duct, the air circulation system provides fresh air from ISS into Dragon. To utilize the maximum volume of Dragon for cargo packaging, the Dragon ECS air circulation system is designed around cargo rack optimization. At the same time, the air circulation system is designed to meet the National Aeronautics Space Administration (NASA) inter-module and intra-module ventilation requirements and acoustic requirements. A flight like configuration of the Dragon capsule including the air circulation system was recently assembled for testing to assess the design for inter-module and intra-module ventilation and acoustics. The testing included the Dragon capsule, and flight configuration in the pressure section with cargo racks, lockers, all of the air circulation components, and acoustic treatment. The air circulation test was also used to verify the Computational Fluid Dynamics (CFD) model of the Dragon capsule. The CFD model included the same Dragon internal geometry that was assembled for the test. This paper will describe the Dragon air circulation system design which has been verified by testing the system and with CFD analysis.

  9. Isotopic composition of precipitation during different atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Brenčič, Mihael; Kononova, Nina; Vreča, Polona

    2016-04-01

    Precipitation generating processes depend on atmospheric circulation patterns and consequently it is expected that its water stable isotopic composition of hydrogen and oxygen is related to them. Precipitation generated at similar atmospheric circulation patterns should have similar empirical distribution of δ2H and δ18O values. There are several approaches in which atmospheric circulation patterns are classified as elementary air circulation mechanisms - ECM; in our approach we have applied Dzerdzeevskii classification. Two types of models of relation between ECM and isotopic composition of precipitation are proposed; first is based on the linear combination of δ2H and δ18O values with precipitation amount weighted average (Brenčič et al., 2015) and the second new one is based on the multiple regression approach. Both approaches make possible also to estimate empirical distributions' dispersion parameters. Application of the models is illustrated on the precipitation records from Ljubljana and Portorož GNIP stations, Slovenia. Estimated values of the parameters for empirical distributions of δ2H and δ18O of each ECM subtype have shown that calculated estimates are reasonable. Brenčič, M., Kononova, N.K., Vreča, P., 2015: Relation between isotopic composition of precipitation and atmospheric circulation patterns. Journal of Hydrology 529, 1422-1432: doi: 10.1016/j.jhydrol.2015.08.040

  10. Relation between isotopic composition of precipitation and atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Brenčič, Mihael; Kononova, Nina K.; Vreča, Polona

    2015-10-01

    Precipitation generating processes depend on atmospheric circulation patterns and consequently it is expected that its water stable isotopic composition of hydrogen and oxygen is related to them. Precipitation generated at similar atmospheric circulation patterns should have similar empirical distribution of δ2H and δ18O values. Mathematical model based on the linear combination of δ2H and δ18O values and on precipitation amount weighted average related to elementary air circulation mechanisms - ECM is proposed. The model enables estimation of average δ2H and δ18O values and their standard deviation for the precipitation generated at distinctive atmospheric circulation patterns. Approach in which atmospheric circulation patterns were classified as ECM based on the Dzerdzeevskii classification was applied. Application of the model is illustrated on the long term precipitation record from Ljubljana GNIP station Slovenia. Estimated values of the parameters for empirical distributions of δ2H and δ18O of each ECM subtype have shown that calculated estimates are reasonable. Further applications of the proposed model enable new insight into the understanding of isotopes spatial and temporal distribution in precipitation important also for better understanding of climate proxies.

  11. Circulation patterns in active lava lakes

    NASA Astrophysics Data System (ADS)

    Redmond, T. C.; Lev, E.

    2014-12-01

    Active lava lakes provide a unique window into magmatic conduit processes. We investigated circulation patterns of 4 active lava lakes: Kilauea's Halemaumau crater, Mount Erebus, Erta Ale and Nyiragongo, and in an artificial "lava lake" constructed at the Syracuse University Lava Lab. We employed visual and thermal video recordings collected at these volcanoes and use computer vision techniques to extract time-dependent, two-dimensional surface velocity maps. The large amount of data available from Halemaumau enabled us to identify several characteristic circulation patterns. One such pattern is a rapid acceleration followed by rapid deceleration, often to a level lower than the pre-acceleration level, and then a slow recovery. Another pattern is periodic asymmetric peaks of gradual acceleration and rapid deceleration, or vice versa, previously explained by gas pistoning. Using spectral analysis, we find that the dominant period of circulation cycles at approximately 30 minutes, 3 times longer than the dominant period identified previously for Mount Erebus. Measuring a complete surface velocity field allowed us to map and follow locations of divergence and convergence, therefore upwelling and downwelling, thus connecting the surface flow with that at depth. At Nyiragongo, the location of main upwelling shifts gradually, yet is usually at the interior of the lake, for Erebus it is usually along the perimeter yet often there is catastrophic downwelling at the interior; For Halemaumau upwelling/downwelling position is almost always on the perimeter. In addition to velocity fields, we developed an automated tool for counting crustal plates at the surface of the lava lakes, and found a correlation, and a lag time, between changes if circulation vigor and the average size of crustal plates. Circulation in the artificial basaltic lava "lake" was limited by its size and degree of foaming, yet we measured surface velocities and identify patterns. Maximum surface velocity

  12. Monitoring Air Circulation Under Reduced Pressures

    NASA Astrophysics Data System (ADS)

    Rygalov, Vadim

    Adequate air circulation is required for controlled environments to maintain uniform temperature and humidity control, and hence the ability to measure air flow accurately is important. Human and associated life support habitats (e.g.,. plant production systems) for future space missions will likely be operated at pressures less than 100 kPa to minimize gas leakage and structural mass. Under such reduced pressures, the outputs from conventional anemometers for monitoring air flow can change and require re-calibration. These effects of atmospheric pressure on different types of air flow measurements are not completely understood; hence we compared the performance of several air flow sensors across a range of hypobaric pressures. Sensors included a propeller type anemometer, a hot-wire anemometer, and a Pitot-tube based device. Theoretical schematics (including mathematical models) underlying these measurements were developed. Results demonstrated that changes in sensor outputs were predictable based on their operating principles, and that corrections could be developed for sensors calibrated under normal Earth atmosphere pressure ( 100 kPa) and then used at different pressures. The potential effects of hypobaric atmospheres and their altered air flows on plant physiology are also discussed.

  13. 40 CFR 230.23 - Current patterns and water circulation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Current patterns and water circulation... Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.23 Current patterns and water circulation. (a) Current patterns and water circulation are the physical movements...

  14. 40 CFR 230.23 - Current patterns and water circulation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Current patterns and water circulation... Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.23 Current patterns and water circulation. (a) Current patterns and water circulation are the physical movements...

  15. 40 CFR 230.23 - Current patterns and water circulation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Current patterns and water circulation... Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.23 Current patterns and water circulation. (a) Current patterns and water circulation are the physical movements...

  16. 40 CFR 230.23 - Current patterns and water circulation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Current patterns and water circulation... Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.23 Current patterns and water circulation. (a) Current patterns and water circulation are the physical movements...

  17. Reversing circulation patterns in a tropical estuary

    NASA Astrophysics Data System (ADS)

    Valle-Levinson, Arnoldo; Bosley, Kathryn T.

    2003-10-01

    A combination of current velocity and water density measurements was used to characterize the basic patterns of water exchange in the Gulf of Fonseca, a tropical estuary on the Pacific Ocean side of Central America. The measurements were obtained during spring and neap tides in March (dry season) and June (wet season) of 2001 and consisted of profiles of current velocity and density along four transects. From mid-March to mid-April a time series of hourly surface current velocity maps was also obtained with a high-frequency radar system of two antennas. The sampling transects and the radar coverage concentrated in the portion of the estuary that has open communication with the ocean. During the dry season, water exchange at the entrance to the gulf suggested an inverse estuarine circulation that was more robust, and its dynamics were closer to geostrophy during neap than during spring tides. It is likely that salinity increased toward the tributaries of the system and then decreased within those tributaries because of the persistent influence of fresh water. In contrast, during the wet season, salinity decreased into the estuary, and the circulation resembled that of a typical estuary. In this season the fortnightly modulation of exchange flows was masked by wind effects, which also played a relevant role in the dynamics. The net volume inflows measured in both seasons suggested that the residence time of the Gulf of Fonseca varies from 2 weeks to 1 month.

  18. Conveying Global Circulation Patterns in HDTV

    NASA Astrophysics Data System (ADS)

    Gardiner, N.; Janowiak, J.; Kinzler, R.; Trakinski, V.

    2006-12-01

    The American Museum of Natural History has partnered with the National Centers for Environmental Prediction (NCEP) to educate general audiences about weather and climate using high definition video broadcasts built from half-hourly global mosaics of infrared (IR) data from five geostationary satellites. The dataset being featured was developed by NCEP to improve precipitation estimates from microwave data that have finer spatial resolution but poorer temporal coverage. The IR data span +/-60 degrees latitude and show circulation patterns at sufficient resolution to teach informal science center visitors about both weather and climate events and concepts. Design and editorial principles for this media program have been guided by lessons learned from production and annual updates of visualizations that cover eight themes in both biological and Earth system sciences. Two formative evaluations on two dates, including interviews and written surveys of 480 museum visitors ranging in age from 13 to over 60, helped refine the design and implementation of the weather and climate program and demonstrated that viewers understood the program's initial literacy objectives, including: (1) conveying the passage of time and currency of visualized data; (2) geographic relationships inherent to atmospheric circulation patterns; and (3) the authenticity of visualized data, i.e., their origin from earth-orbiting satellites. Surveys also indicated an interest and willingness to learn more about weather and climate principles and events. Expanded literacy goals guide ongoing, biweekly production and distribution of global cloud visualization pieces that reach combined audiences of approximately 10 million. Two more rounds of evaluation are planned over the next two years to assess the effectiveness of the media program in addressing these expanded literacy goals.

  19. Plateau effects on diurnal circulation patterns

    SciTech Connect

    Reiter, E.R.; Tang, M.

    1984-04-01

    The diurnal variation of 850 mb heights, the detailed distribution of which could be assessed by the inclusion of surface data, and of resultant winds over, and in the vicinity of, the Great Basin reveals clearly a plateau-wind circulation during summer. This circulation reverses between day and night and appears to include the low-level jet stream over Texas and Oklahoma, as well as the time of occurrence of thunderstorms. This plateau circulation system interacts with local mountain-valley breeze systems. The thickness of the daytime inflow and nighttime outflow layer over the plateau is approximately 2 km. 19 references, 11 figures, 1 table.

  20. Pellet stove with enhanced air circulation efficiency

    SciTech Connect

    Burke, T.M.; Burke, W.L.

    1992-06-23

    This patent describes a stove for converting fuel to heat. It comprises means defining a fuel storage area; means for pressurizing the fuel storage area, the means comprising a single air blowing means; means defining a combustion area for allowing combustion to take place; vent means for venting air from the combustion area; means defining a heat exchange area adjacent to and in contact with the combustion area for removing heat from the combustion area; and means for conducting pressurized air from the fuel storage area directly to the combustion area and directly to the heat exchange area.

  1. Circulation patterns governing October snowfalls in southern Siberia

    NASA Astrophysics Data System (ADS)

    Bednorz, Ewa; Wibig, Joanna

    2015-12-01

    This study is focused on early fall season in southern Siberia (50-60 N) and is purposed as a contribution to the discussion on the climatic relevance of October Eurasian snow cover. Analysis is based on the daily snow depth data from 43 stations from years 1980-2012, available in the database of All-Russian Research Institute of Hydrometeorological Information—World Data Centre. The snow cover season in southern Siberia starts in early autumn and the number of days with snowfall varies from less than 5 days in the southernmost zone along the parallel 50 N to more than 25 days in the northeastern part of the analyzed area. October snowfall in southern Siberia is associated with occurrence of negative anomalies of sea level pressure (SLP), usually spreading right over the place of recorded intense snowfall or extending eastward from it. Negative anomalies of air temperature at the 850 hPa geopotential level (T850) occurring with increased cyclonic activity are also observed. Negative T850 anomalies are located west or northwest of the SLP depressions. Counterclockwise circulation around low-pressure systems transports cold Arctic air from the north or even colder Siberian polar air from the east, to the west, and northwest parts of cyclones, and induces negative anomalies of temperature. The pattern of T850 anomalies during heavy snowfalls in the eastern part of the southern Siberia is shifted counterclockwise in regard to SLP anomalies: the strongest negative T850 anomalies are located west or northwest of the SLP depressions.

  2. Topographically induced circulation patterns and mixing over Condor seamount

    NASA Astrophysics Data System (ADS)

    Bashmachnikov, I.; Loureiro, C. M.; Martins, A.

    2013-12-01

    Analysis of mean and oscillatory circulation patterns over Condor seamount, situated near the central group of the Azores islands, was performed. During 1.5 years of observations, at least half of the time an anticyclonic cap was established over the summit. The vortex was characterised by a strong asymmetry: it was shifted to the south of the summit and strongly stretched along the gentle eastern and western slopes of the seamount.

  3. Pseudo Random Classification of Circulation Patterns - Comparison to Deliberate Methods

    NASA Astrophysics Data System (ADS)

    Philipp, Andreas

    2010-05-01

    Classification of circulations patterns, e.g. of sea level pressure patterns, can be done by many different methods, e.g. by cluster analysis, methods based on eigenvalues or those based on the leader algorithm like the Lund classification. However none of these methods can give clear advice on the problem of appropriate numbers of classes and even though the number is decided different methods lead to different results. High efforts are made to find methods leading to indisbutable results. However, doubts on the classifiability of tropospheric circulation states have been raised recently and the existence of natural groups of similar patterns within the circulation data, which might be caused by circulation regimes, are questionable. If those groups or clusters exist, methods which are designed to find them, in particular cluster analysis, should be superior to classification schemes based on pseudo random definition of classes. In order to prove this assumption, a classification method called "random centroids" has been designed, for each class choosing one single circulation pattern using a random number generator and assigning all remaining patterns to them according to the minimum Euclidean distance. Evaluation metrics like the "explained cluster variance" for pressure, temperature and precipitation are calculated in order to compare those pseudo random classifications to classifications provided by the cost733cat dataset including many different classification catalogs for various methods (COST Action 733 "Harmonisation and Applications of Weather Type Classifications for European regions"). By running the randomcent method 1000 times the empirical probability density function of the evaluation metrics can be established and provides information about the probability for the established deliberate methods to be better than random classifications. The results show that most of the classifications fail to succeed the 95th percentile of the empirical probability

  4. Autoregressive Logistic Regression Applied to Atmospheric Circulation Patterns

    NASA Astrophysics Data System (ADS)

    Guanche, Yanira; Mínguez, Roberto; Méndez, Fernando J.

    2013-04-01

    The study of atmospheric patterns, weather types or circulation patterns, is a topic deeply studied by climatologists, and it is widely accepted to disaggregate the atmospheric conditions over regions in a certain number of representative states. This consensus allows simplifying the study of climate conditions to improve weather predictions and a better knowledge of the influence produced by anthropogenic activities on the climate system. Once the atmospheric conditions have been reduced to a catalogue of representative states, it is desirable to dispose of numerical models to improve our understanding about weather dynamics, i.e. i) to analyze climate change studying trends in the probability of occurrence of weather types, ii) to study seasonality and iii) to analyze the possible influence of previous states (Autoregressive terms or Markov Chains). This work introduces the mathematical framework to analyze those effects from a qualitative point of view. In particular, an autoregressive logistic regression model, which has been successfully applied in medical and pharmacological research fields, is presented. The main advantages of autoregressive logistic regression are that i) it can be used to model polytomous outcome variables, such as circulation types, and ii) standard statistical software can be used for fitting purposes. To show the potential of these kind of models for analyzing atmospheric conditions, a case of study located in the Northeastern Atlantic is described. Results obtained show how the model is capable of dealing simultaneously with predictors related to different time scales, which can be used to simulate the behaviour of circulation patterns.

  5. Autoregressive logistic regression applied to atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Guanche, Y.; Mínguez, R.; Méndez, F. J.

    2014-01-01

    Autoregressive logistic regression models have been successfully applied in medical and pharmacology research fields, and in simple models to analyze weather types. The main purpose of this paper is to introduce a general framework to study atmospheric circulation patterns capable of dealing simultaneously with: seasonality, interannual variability, long-term trends, and autocorrelation of different orders. To show its effectiveness on modeling performance, daily atmospheric circulation patterns identified from observed sea level pressure fields over the Northeastern Atlantic, have been analyzed using this framework. Model predictions are compared with probabilities from the historical database, showing very good fitting diagnostics. In addition, the fitted model is used to simulate the evolution over time of atmospheric circulation patterns using Monte Carlo method. Simulation results are statistically consistent with respect to the historical sequence in terms of (1) probability of occurrence of the different weather types, (2) transition probabilities and (3) persistence. The proposed model constitutes an easy-to-use and powerful tool for a better understanding of the climate system.

  6. Satellite studies of turbidity and circulation patterns in Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Srna, R.; Treasure, W. M.; Rogers, R.

    1973-01-01

    Satellite imagery from four successful ERTS-1 passes over Delaware Bay during different portions of the tidal cycle are interpreted with special emphasis on visibility of suspended sediment and its use as a natural tracer for gross circulation patters. The MSS red band (band 5) appears to give the best contrast, although the sediment patterns are represented by only a few neighboring shades of grey. Color density slicing improves the differentiation of turbidity levels. However, color additive enhancements are of limited value since most of the information is in a single color band. The ability of ERTS-1 to present a synoptic view of the surface circulation over the entire bay is shown to be a valuable and unique contribution of ERTS-1 to coastal oceanography.

  7. Macroscale Circulation Patterns as Reflected in Spatial and Temporal Patterns of Precipitation over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Conselyea, K.; Yin, Z.

    2007-12-01

    Circulation patterns such as the NAO, PNA, and AO have been known to impact climate both near the action centers and at great distances away. These macroscale circulation patterns can impact regional wind patterns, temperature gradients and pressure gradients. Changes in these gradients can cause an onset of various weather conditions including precipitation. Precipitation across the Tibetan Plateau is influenced by known phenomena such as monsoon systems and teleconnections. Previous studies have suggested that other forcing mechanisms also may play a vital role in influencing precipitation in this region. To evaluate potential forcing factors affecting precipitation across the Tibetan Plateau, the relationship between the spatial and temporal patterns of precipitation and the regional and macroscale circulation patterns will be investigated. To explore this relationship statistical analysis, such as Principal Component Analysis (PCA), Correlation Field Analysis, and Canonical Correspondence Analysis (CCA), is preformed. This study also incorporates tree ring chronologies from Qilian junipers (Sabina przewalskii Kom.) sampled in the Qaidam Basin, northeastern Tibetan Plateau. These data have been used in previous studies to indicate environmental change, and tree rings taken from this region have shown signatures of circulation patterns such as Arctic Oscillation (AO). Based on the relationship between tree ring data and circulation patterns it is possible to reconstruct past events. This information along with examination of National Centers for Environmental Protection/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data will aid in the examination of the relationship between teleconnection patterns and precipitation, and develop a greater understanding of the precipitation variability across the Tibetan Plateau.

  8. Variability patterns of the general circulation and sea water temperature in the North Sea

    NASA Astrophysics Data System (ADS)

    Mathis, M.; Elizalde, A.; Mikolajewicz, U.; Pohlmann, T.

    2015-06-01

    This study investigates patterns of spatio-temporal variability in the North Sea and their major driving mechanisms. Leading variability modes of the general circulation and sea water temperature are extracted from model results by means of Empirical Orthogonal Functions (EOF) analysis. The model results originate from an uncoupled simulation with the global ocean model MPIOM, forced with ERA40 reanalysis data at the air-sea interface. For this regional model study, MPIOM has been run with a stretched grid configuration enabling higher horizontal resolution in the Northwest European Shelf and North Atlantic ocean. The analysis is applied to interannual variabilities of winter and summer separately. The results indicate that on seasonal scales the leading variability mode of the general circulation affects the entire North Sea, accompanied by significant inflow anomalies through the Fair-Isle Passage. Correlations of the corresponding Principal Component (PC) with wind density functions reveal the circulation anomalies to coincide with westerly and south-westerly wind anomalies. The second mode describes circulation anomalies along the Norwegian Trench and English Channel, which correlate with north-westerly wind anomalies caused by variations in large-scale atmospheric pressure areas centered over the British Isles. For sea water temperature, distinct variability patterns are induced by variable surface heat fluxes, vertical mixing, and variable advective heat fluxes. The first mode of both the general circulation and water temperature in winter mainly represents the response to atmospheric variations in the North Atlantic Oscillation (NAO). However, the higher modes account for such variabilities that cannot be explained by the NAO. As a consequence of the integrated effects of the different variability modes on the circulation system and heat content, local correlations of the NAO with volume transports and water temperature are weakened in the regions of

  9. The role of aerosol in altering North Atlantic atmospheric circulation in winter and air-quality feedbacks

    NASA Astrophysics Data System (ADS)

    Pausata, F. S. R.; Gaetani, M.; Messori, G.; Kloster, S.; Dentener, F. J.

    2014-09-01

    Numerical model scenarios of future climate depict a global increase in temperatures and changing precipitation patterns, driven by increasing greenhouse gas (GHG) concentrations. Aerosol concentrations also play an important role in altering Earth's radiation budget and consequently surface temperature. Here, we use the general circulation aerosol model ECHAM5-HAM, coupled to a mixed layer ocean model, to investigate the impacts of future air pollution mitigation strategies in Europe on winter atmospheric circulation over the North Atlantic. We analyze the extreme case of a maximum feasible end-of-pipe reduction of aerosols in the near future (2030), in combination with increasing GHG concentrations. Our results show a more positive North Atlantic Oscillation (NAO) mean state in the near future, together with a significant eastward shift of the southern centre of action of the sea level pressure (SLP). Moreover, we show a significantly increased blocking frequency over the western Mediterranean. By separating the aerosol and GHG impacts, our study suggests that the aerosol abatement in the near future may be the primary driver of such circulation changes. All these concomitant modifications of the atmospheric circulation over the Euro-Atlantic sector lead to more stagnant weather conditions that favor air pollutant accumulation in the Mediterranean, especially in the western sector. These changes in atmospheric circulation should be included in future air pollution mitigation assessments. Our results suggest that an evaluation of NAO changes in individual climate model simulations will allow an objective assessment of the role of changes in wintertime circulation on future air quality.

  10. A comparative Study of Circulation Patterns at Active Lava Lakes

    NASA Astrophysics Data System (ADS)

    Lev, Einat; Oppenheimer, Clive; Spampinato, Letizia; Hernandez, Pedro; Unglert, Kathi

    2016-04-01

    Lava lakes present a rare opportunity to study magma dynamics in a large scaled-up "crucible" and provide a unique natural laboratory to ground-truth dynamic models of magma circulation. The persistence of lava lakes allows for long-term observations of flow dynamics and of lava properties, especially compared to surface lava flows. There are currently five persistent lava lakes in the world: Halemaumau in Kilauea (Hawaii, USA), Erta Ale (Ethiopia), Nyiragongo (Congo), Erebus (Antarctica), and Villarica (Chile). Marum and Benbow craters of Ambrym volcano (Vanuatu) and Masaya (Nicaragua) have often hosted lava lakes as well. We use visible-light and thermal infrared time-lapse and video footage collected at all above lakes (except Villarica, where the lake is difficult to observe), and compare the circulation patterns recorded. We calculate lake surface motion from the footage using the optical flow method (Lev et al., 2012) to produce 2D velocity fields. We mined both the surface temperature field and the surface velocity field for patterns using machine learning techniques such as "self-organizing maps (SOMs)" and "principle component analysis (PCA)". We use automatic detection technique to study the configuration of crustal plates at the lakes' surface. We find striking differences among the lakes, in flow direction, flow speed, frequency of changes in flow direction and speed, location and consistency of upwelling and downwelling, and crustal plate configuration. We relate the differences to lake size, shallow conduit geometry, lava viscosity, crystal and gas content, and crust integrity.

  11. Coastal recirculation potential affecting air pollutants in Portugal: The role of circulation weather types

    NASA Astrophysics Data System (ADS)

    Russo, Ana; Gouveia, Célia; Levy, Ilan; Dayan, Uri; Jerez, Sonia; Mendes, Manuel; Trigo, Ricardo

    2016-06-01

    Coastal zones are under increasing development and experience air pollution episodes regularly. These episodes are often related to peaks in local emissions from industry or transportation, but can also be associated with regional transport from neighbour urban areas influenced by land-sea breeze recirculation. This study intends to analyze the relation between circulation weather patterns, air mass recirculation and pollution levels in three coastal airsheds of Portugal (Lisbon, Porto and Sines) based on the application of an objective quantitative measure of potential recirculation. Although ventilation events have a dominant presence throughout the studied 9-yrs period on all the three airsheds, recirculation and stagnation conditions occur frequently. The association between NO2, SO2 and O3 levels and recirculation potential is evident during summer months. Under high average recirculation potential and high variability, NO2 and SO2 levels are higher for the three airsheds, whilst for O3 each airshed responds differently. This indicates a high heterogeneity among the three airsheds in (1) the type of emission - traffic or industry - prevailing for each contaminant, and (2) the response to the various circulation weather patterns and recirculation situations. Irrespectively of that, the proposed methodology, based on iterative K-means clustering, allows to identify which prevailing patterns are associated with high recirculation potential, having the advantage of being applicable to any geographical location.

  12. Solar influences on spatial patterns of Eurasian winter temperature and atmospheric general circulation anomalies

    NASA Astrophysics Data System (ADS)

    Chen, Haishan; Ma, Hedi; Li, Xing; Sun, Shanlei

    2015-09-01

    Solar influences on spatial patterns of Eurasian winter climate and possible mechanisms are investigated based on a multiple linear regression method and multisource observational and reanalysis data. Robust and significant solar signals are detected in Eurasian surface air temperature (SAT), and strong solar activity evidently warms most area of the continent. The spatial pattern of sea level pressure (SLP) responses to solar activity is similar but not identical to that of the North Atlantic Oscillation (NAO). Compared to the NAO, geographic distribution of solar-induced SLP anomalies shifts eastward, with significantly enhanced influences over northern Eurasia. Relatively weaker solar signals were also found in mid-to-upper troposphere. The spatial pattern of 500 hPa geopotential anomalies resembles a negative Scandinavia teleconnection pattern, and the 200 hPa subtropical jet is weakened, while zonal wind at high latitudes is enhanced due to strong solar activity. The anomalous zonal circulations can be attributed to the "top-down" mechanism. During high solar activity winters, an enhanced stratospheric zonal wind anomaly propagates downward, causing zonal wind anomalies in the troposphere. However, the "bottom-up" mechanisms may provide more reasonable explanations of the distinct solar influences on Eurasian climate. Solar-induced strong warm advection in lower atmosphere tends to increase SAT but decrease SLP, resulting in enhanced solar influences over northern Eurasia. Meanwhile, change in the land-ocean thermal contrast (LOTC) could also amplify the circulation anomaly. Inhomogeneous surface heating caused by anomalous solar activity modifies LOTC, which probably enhances the solar-induced circulation patterns. Such a positive feedback may potentially strengthen the solar influences.

  13. Changes in large-scale air circulation and connection with climate variables in Romania

    NASA Astrophysics Data System (ADS)

    Stefan, Sabina; Barbu, Nicu

    2016-04-01

    The aim of this paper is the analysis of the relationship between climate variables (seasonal mean air temperature - T2m, and seasonal amount of precipitation - PP) and large-scale air circulation. In order to achieve this, the air circulation types were derived from GrossWetterTypen (GWT) and WetterLagenKlassifikation (WLK) Catalogues developed within COST733 framework. Daily air circulation types are divided into 18 groups according to the GWT Catalogue and in 40 groups according to the WLK Catalogue and for each type winter (DJF) and summer (JJA) occurrence frequency were calculated. To this end the Pearson correlation coefficient between climate variables and circulation type's frequency were computed. The results reveals that in wintertime the GWT circulation types captures better than WLK circulation types the T2m variability in time that for summer the WLK circulation types captures better than GWT circulation types. This is due to the seasonal variability of the horizontal extension of air masses. We found that the T2m is positive correlated to anticyclonic circulation types and negative correlated with cyclonic types and the PP is correlated to the cyclonic circulation and negative correlated to anticyclonic ones. Additionally, the trend significance of the climate variables as well as air circulation types have been analysed with the non-parametric Mann-Kendall test. The changes of the trends were detected by employing the non-parametric Pettit test. From the trend analysis we can state that some of the anticyclonic circulation types presents upward tendency and some of the cyclonic circulation presents downward tendency. This is an important results because explain the upward trend of the T2m and the downward trend of the PP.

  14. Influence of large-scale atmospheric circulation on marine air intrusion toward the East Antarctic coast

    NASA Astrophysics Data System (ADS)

    Kurita, Naoyuki; Hirasawa, Naohiko; Koga, Seizi; Matsushita, Junji; Steen-Larsen, Hans Christian; Masson-Delmotte, Valérie; Fujiyoshi, Yasushi

    2016-09-01

    Marine air intrusions into Antarctica play a key role in high-precipitation events. Here we use shipboard observations of water vapor isotopologues between Australia and Syowa on the East Antarctic coast to elucidate the mechanism by which large-scale circulation influences marine air intrusions. The temporal isotopic variations at Syowa reflect the meridional movement of a marine air front. They are also associated with atmospheric circulation anomalies that enhance the southward movement of cyclones over the Southern Ocean. The relationship between large-scale circulation and the movement of the front is explained by northerly winds which, in association with cyclones, move toward the Antarctic coast and push marine air with isotopically enriched moisture into the inland covered by glacial air with depleted isotopic values. Future changes in large-scale circulation may have a significant impact on the frequency and intensity of marine air intrusion into Antarctica.

  15. Variation in summer surface air temperature over Northeast Asia and its associated circulation anomalies

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Hong, Xiaowei; Lu, Riyu; Jin, Aifen; Jin, Shizhu; Nam, Jae-Cheol; Shin, Jin-Ho; Goo, Tae-Young; Kim, Baek-Jo

    2016-01-01

    This study investigates the interannual variation of summer surface air temperature over Northeast Asia (NEA) and its associated circulation anomalies. Two leading modes for the temperature variability over NEA are obtained by EOF analysis. The first EOF mode is characterized by a homogeneous temperature anomaly over NEA and therefore is called the NEA mode. This anomaly extends from southeast of Lake Baikal to Japan, with a central area in Northeast China. The second EOF mode is characterized by a seesaw pattern, showing a contrasting distribution between East Asia (specifically including the Changbai Mountains in Northeast China, Korea, and Japan) and north of this region. This mode is named the East Asia (EA) mode. Both modes contribute equivalently to the temperature variability in EA. The two leading modes are associated with different circulation anomalies. A warm NEA mode is associated with a positive geopotential height anomaly over NEA and thus a weakened upper-tropospheric westerly jet. On the other hand, a warm EA mode is related to a positive height anomaly over EA and a northward displaced jet. In addition, the NEA mode tends to be related to the Eurasian teleconnection pattern, while the EA mode is associated with the East Asia-Pacific/Pacific-Japan pattern.

  16. Consortial Book Circulation Patterns: The OCLC-OhioLINK Study

    ERIC Educational Resources Information Center

    O'Neill, Edward T.; Gammon, Julia A.

    2014-01-01

    The OhioLINK consortium and OCLC Research collected and analyzed circulation data for libraries within the consortium. The study, which examines the circulation of 28,475,701 items from more than 100 academic libraries, is the largest and most diverse compilation of academic usage data for books ever collected. The authors outline the study…

  17. Satellite observations of surface temperature patterns induced by synoptic circulation over the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Lensky, Itamar; Dayan, Uri

    2013-04-01

    Land Surface Temperature (LST) controls most physical and biological processes on Earth. Knowledge of the LST at high spatial resolution enables representation of different climate regimes. The main factors controlling LST are the seasonal and diurnal cycles, land cover, cloud cover, and atmospheric processes at several scales. Lensky and Dayan analyzed atmospheric processes at the topoclimatic scale, and the mesoscale (Lensky and Dayan 2011, 2012). Here we will demonstrate an analysis of the spatial distribution of LST anomaly as affected by typical synoptic circulation patterns over the Eastern Mediterranean (EM). LST anomaly is defined as the difference between daily and climatological LST. Using LST anomaly reduces the effects of land cover and the seasonal and diurnal cycles, enabling a better detection of surface temperature patterns induced by synoptic circulation. In this study we used all available 2000-2012 NASA daily MODIS LST data over the EM, together with NCEP/NCAR Reanalysis data of SLP, surface winds and Omega (at 700hPa). We will present two frequent synoptic circulation patterns as classified by Levy and Dayan (2008) to demonstrate the LST patterns induced by synoptic circulation over the EM. The first is the "Red Sea Trough" (RST) with eastern axis, which is an extension of a low surface pressure from a tropical depression toward the Red Sea, penetrating up north as far as Turkey. It migrates from south to north and mostly frequent during the autumn. The axis of the RST separates distinctively between regions of positive (warm) anomalies over Turkey and regions of negative anomalies (cold) over Egypt induced by the wind flow from both sides of the axis. The second synoptic circulation pattern is "shallow Cyprus low to the north", which is a disturbance of the polar front extending southward. This synoptic system some times migrates over the Mediterranean eastward toward the EM during the winter season. The strong northwesterly flow featuring the

  18. The role of aerosol in altering North Atlantic atmospheric circulation in winter and its impact on air quality

    NASA Astrophysics Data System (ADS)

    Pausata, F. S. R.; Gaetani, M.; Messori, G.; Kloster, S.; Dentener, F. J.

    2015-02-01

    Numerical model scenarios of future climate depict a global increase in temperatures and changing precipitation patterns, primarily driven by increasing greenhouse gas (GHG) concentrations. Aerosol particles also play an important role by altering the Earth's radiation budget and consequently surface temperature. Here, we use the general circulation aerosol model ECHAM5-HAM, coupled to a mixed layer ocean model, to investigate the impacts of future air pollution mitigation strategies in Europe on winter atmospheric circulation over the North Atlantic. We analyse the extreme case of a maximum feasible end-of-pipe reduction of aerosols in the near future (2030), in combination with increasing GHG concentrations. Our results show a more positive North Atlantic Oscillation (NAO) mean state by 2030, together with a significant eastward shift of the southern centre of action of sea-level pressure (SLP). Moreover, we show a significantly increased blocking frequency over the western Mediterranean. By separating the impacts of aerosols and GHGs, our study suggests that future aerosol abatement may be the primary driver of both the eastward shift in the southern SLP centre of action and the increased blocking frequency over the western Mediterranean. These concomitant modifications of the atmospheric circulation over the Euro-Atlantic sector lead to more stagnant weather conditions that favour air pollutant accumulation, especially in the western Mediterranean sector. Changes in atmospheric circulation should therefore be included in future air pollution mitigation assessments. The indicator-based evaluation of atmospheric circulation changes presented in this work will allow an objective first-order assessment of the role of changes in wintertime circulation on future air quality in other climate model simulations.

  19. Impact of Large-scale Circulation Patterns on Surface Ozone Variability in Houston-Galveston-Brazoria

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Jia, B.; Xie, Y.

    2015-12-01

    The Bermuda High (BH) is a key driver of large-scale circulation patterns for Southeastern Texas and other Gulf coast states in summer, with the expected influence on surface ozone through its modulation of marine air inflow with lower ozone background from the Gulf of Mexico. We develop a statistical relationship through multiple linear regression (MLR) to quantify the impact of the BH variations on surface ozone variability during the ozone season in the Houston-Galveston-Brazoria (HGB) area, a major ozone nonattainment region on the Gulf Coast. We find that the variability in BH location, represented by a longitude index of the BH west edge (BH-Lon) in the MLR, explains 50-60% of the year-to-year variability in monthly mean ozone over HGB for Jun and July during 1998-2013, and the corresponding figure for Aug and Sep is 20%. Additional 30%-40% of the ozone variability for Aug and Sep can be explained by the variability in BH strength, represented by two BH intensity indices (BHI) in the MLR, but its contribution is only 5% for June and not significant for July. Including a maximum Through stepwise regression based on Akaike Information Criterion (AIC), the MLR model captures 58~72% of monthly ozone variability during Jun-Sep with a cross-validation R2 of 0.5. This observation-derived statistical relationship will be valuable to constrain model simulations of ozone variability attributable to large-scale circulation patterns.

  20. 40 CFR 230.23 - Current patterns and water circulation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Potential Impacts on Physical and Chemical Characteristics of the Aquatic Ecosystem § 230.23 Current... water in the aquatic ecosystem. Currents and circulation respond to natural forces as modified by...

  1. Identifying a Sea Breeze Circulation Pattern Over the Los Angeles Basin Using Airborne In Situ Carbon Dioxide Measurements

    NASA Astrophysics Data System (ADS)

    Brannan, A. L.; Schill, S.; Trousdell, J.; Heath, N.; Lefer, B. L.; Yang, M. M.; Bertram, T. H.

    2014-12-01

    The Los Angeles Basin in Southern California is an optimal location for a circulation study, due to its location between the Pacific Ocean to the west and the Santa Monica and San Gabriel mountain ranges to the east, as well as its booming metropolitan population. Sea breeze circulation carries air at low altitudes from coastal to inland regions, where the air rises and expands before returning back towards the coast at higher altitudes. As a result, relatively clean air is expected at low altitudes over coastal regions, but following the path of sea breeze circulation should increase the amount of anthropogenic influence. During the 2014 NASA Student Airborne Research Program, a highly modified DC-8 aircraft completed flights from June 23 to 25 in and around the LA Basin, including missed approaches at four local airports—Los Alamitos and Long Beach (coastal), Ontario and Riverside (inland). Because carbon dioxide (CO2) is chemically inert and well-suited as a conserved atmospheric tracer, the NASA Langley Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument was used to make airborne in situ carbon dioxide measurements. Combining measured wind speed and direction data from the aircraft with CO2 data shows that carbon dioxide can be used to trace the sea breeze circulation pattern of the Los Angeles basin.

  2. Patterns in atmospheric circulation affect emission sources contributing to nitrogen deposition in the Columbia River Gorge, Pacific Northwest USA

    NASA Astrophysics Data System (ADS)

    Anderson, S. M.; Chung, S. H.; Welker, J. M.; Harlow, B.; Evans, R. D.

    2014-12-01

    The Columbia River Gorge separating Oregon and Washington provides an ideal setting to investigate how atmospheric circulation patterns determine types of emission sources contributing to atmospheric deposition. Up-gorge and down-gorge atmospheric circulation patterns each provide a different suite of emission sources. Up-gorge airflow originates in the Portland-Vancouver metro area dominated by urban and industrial sources. Down-gorge patterns originate in the Columbia River basin, which is dominated by agricultural production. We tested the dependence of emission sources contributing to atmospheric deposition on circulation patterns by measuring the isotopic composition of nitrate (NO3-) in 2003-2004 precipitation samples from the WA98-Columbia River Gorge NADP & USNIP site. Circulation patterns were determined using back-trajectory analysis with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model using the archived EDAS meteorological dataset. We observed a significant difference (P=0.01) between up-gorge and down-gorge patterns with mean δ15N-NO3- of +1.8 and -2.1‰ for up- and down-gorge, respectively. The differences observed between these two patterns is likely tied to the different emission sources of N found in these different geographic areas. The lower δ15N of down-gorge sources is due to the large amount of agricultural production in the Columbia River basin. Observed values for the up-gorge patterns likely result from industrial and fossil fuel emissions of NOx, the precursor of deposited NO3-, in the Portland-Vancouver area. The significantly greater amount of NO3- in precipitation from up-gorge patterns (0.72 mg/L) compared to down-gorge patterns (0.36 mg/L, P=0.01) supports the influence of urban sources rather than relatively clean marine air which characteristically has low amounts of NO3-. No significant differences are found in δ18Onitrate or Δ17Onitrate between the two patterns, suggesting that atmospheric chemistry

  3. Association between winter precipitation and water level fluctuations in the Great Lakes and atmospheric circulation patterns

    SciTech Connect

    Rodionov, S.N.

    1994-11-01

    Atmospheric precipitation in the Great Lakes basin, as a major mediating variable between atmospheric circulation and lake levels, is analyzed relative to both. The effect of cumulative winter precipitation on lake levels varies from lake to lake and depends on both the state of the lake level itself and air temperature. For periods with a quasi-stable temperature regime, the correlation coefficient between winter precipitation and changes in lake levels from November to spring months reaches 0.8. An analysis of composite maps of mean winter 700-mb heights and sea level pressure for the years with well-above and well-below normal precipitation in the lower Great Lakes basin (Lakes Michigan-Huron, St. Clair, Erie, and Ontario) has shown that changes in precipitation are associated with the wave train structure in the lower and midtroposphere that is similar to the Pacific/North American (PNA) teleconnection pattern. During the positive phase of the PNA-like pattern, when the upper-atmospheric ridge/trough system is amplified, cyclones passing over the Great Lakes basin are frequently of Alberta (Canada) origin and carry relatively small amounts of precipitation. As a result, lake levels tend to decline. On the contrary, during the negative phase of the pattern when the atmospheric circulation is more zonal, the main storm track is oriented from the southwest to the northeast and cyclones bring enough precipitation to induce a rise in lake levels. The effect of the position of the upper-atmospheric trough over the east coast of North America on the precipitation regime in the Great Lakes basin is also demonstrated. 42 refs., 11 figs., 4 tabs.

  4. 24 CFR 3280.715 - Circulating air systems.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... incandescent particles dropped through the register or furnace such as directly under floor registers and the... provided shall be counted as return air area. (c) Joints and seams. Joints and seams of sheet metal...

  5. 24 CFR 3280.715 - Circulating air systems.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... incandescent particles dropped through the register or furnace such as directly under floor registers and the... provided shall be counted as return air area. (c) Joints and seams. Joints and seams of sheet metal...

  6. 24 CFR 3280.715 - Circulating air systems.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... incandescent particles dropped through the register or furnace such as directly under floor registers and the... provided shall be counted as return air area. (c) Joints and seams. Joints and seams of sheet metal...

  7. 24 CFR 3280.715 - Circulating air systems.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... incandescent particles dropped through the register or furnace such as directly under floor registers and the... provided shall be counted as return air area. (c) Joints and seams. Joints and seams of sheet metal...

  8. 24 CFR 3280.715 - Circulating air systems.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... incandescent particles dropped through the register or furnace such as directly under floor registers and the... provided shall be counted as return air area. (c) Joints and seams. Joints and seams of sheet metal...

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

    PubMed

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

    2015-06-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  11. Pattern of maternal circulating CRH in laboratory-housed squirrel and owl monkeys.

    PubMed

    Power, M L; Williams, L E; Gibson, S V; Schulkin, J; Helfers, J; Zorrilla, E P

    2010-11-01

    The anthropoid primate placenta appears to be unique in producing corticotropin-releasing hormone (CRH). Placental CRH is involved in an endocrine circuit key to the production of estrogens during pregnancy. CRH induces cortisol production by the maternal and fetal adrenal glands, leading to further placental CRH production. CRH also stimulates the fetal adrenal glands to produce dehydroepiandrostendione sulfate (DHEAS), which the placenta converts into estrogens. There are at least two patterns of maternal circulating CRH across gestation among anthropoids. Monkeys examined to date (Papio and Callithrix) have an early-to-mid gestational peak of circulating CRH, followed by a steady decline to a plateau level, with a possible rise near parturition. In contrast, humans and great apes have an exponential rise in circulating CRH peaking at parturition. To further document and compare patterns of maternal circulating CRH in anthropoid primates, we collected monthly blood samples from 14 squirrel monkeys (Saimiri boliviensis) and ten owl monkeys (Aotus nancymaae) during pregnancy. CRH immunoreactivity was measured from extracted plasma by using solid-phase radioimmunoassay. Both squirrel and owl monkeys displayed a mid-gestational peak in circulating CRH: days 45-65 of the 152-day gestation for squirrel monkeys (mean±SEM CRH=2,694±276 pg/ml) and days 60-80 of the 133-day gestation for owl monkeys (9,871±974 pg/ml). In squirrel monkeys, circulating CRH declined to 36% of mean peak value by 2 weeks before parturition and then appeared to increase; the best model for circulating CRH over gestation in squirrel monkeys was a cubic function, similar to previous results for baboons and marmosets. In owl monkeys, circulating CRH appeared to reach plateau with no subsequent significant decline approaching parturition, although a cubic function was the best fit. This study provides additional evidence for a mid-gestational peak of maternal circulating CRH in ancestral

  12. Pattern of maternal circulating CRH in laboratory-housed squirrel and owl monkeys

    PubMed Central

    Power, ML; Williams, LE; Gibson, SV; Schulkin, J; Helfers, J; Zorrilla, EP

    2010-01-01

    The anthropoid primate placenta appears to be unique in producing corticotropin-releasing hormone (CRH). Placental CRH is involved in an endocrine circuit key to the production of estrogens during pregnancy. CRH induces cortisol production by the maternal and fetal adrenal glands, leading to further placental CRH production. CRH also stimulates the fetal adrenal glands to produce dehydroepiandrostendione sulfate (DHEAS) which the placenta converts into estrogens. There are at least two patterns of maternal circulating CRH across gestation among anthropoids. Monkeys examined to date (Papio and Callithrix) have an early-to-mid gestational peak of circulating CRH, followed by a steady decline to a plateau level, with a possible rise near parturition. In contrast, humans and great apes have an exponential rise in circulating CRH peaking at parturition. To further document and compare patterns of maternal circulating CRH in anthropoid primates, we collected monthly blood samples on 14 squirrel monkeys (Saimiri boliviensis) and 10 owl monkeys (Aotus nancymaae) during pregnancy. CRH immunoreactivity was measured from extracted plasma by solid-phase RIA. Both squirrel and owl monkeys displayed a mid-gestational peak in circulating CRH: days 45–65 of the 152-day gestation for squirrel monkeys (mean±SEM CRH = 2694±276 pg/ml) and days 60–80 of the 133-day gestation for owl monkeys (9871±974 pg/ml). In squirrel monkeys, circulating CRH declined to 36% of mean peak value by two weeks before parturition and then appeared to increase; the best model for circulating CRH over gestation in squirrel monkeys was a cubic function, similar to previous results for baboons and marmosets. In owl monkeys, circulating CRH appeared to plateau with no subsequent significant decline approaching parturition, although a cubic function was the best fit. This study provides additional evidence for a mid-gestational peak of maternal circulating CRH in ancestral anthropoids that has been lost

  13. Patterns of influenza B circulation in Brazil and its relevance to seasonal vaccine composition.

    PubMed

    Barros, Eliana Nogueira Castro de; Cintra, Otavio; Rossetto, Erika; Freitas, Laís; Colindres, Romulo

    2016-01-01

    Data on the burden of disease and circulation patterns of influenza B lineages for Brazil are limited. This review aims to describe the pattern of influenza B occurrence in Brazil to have a better understanding of its epidemiology and its relevance when considering seasonal influenza vaccine composition. A review of the data including analysis of international and local surveillance data as well as information from online search of databases using Medical Subject Headings terms in conjunction with screening of abstracts from scientific events was performed. Based on international epidemiologic surveillance data, moderate levels of influenza B disease (19%; 2006-2014) were observed. Of these nine years, it was possible to compare data from three years (2007, 2008 and 2013) which have information on the circulating influenza B lineage. Co-circulation of influenza B lineages was observed in all these three influenza seasons, of which, during one season, a high degree of mismatch between the vaccine lineage and the predominant circulating lineage (91.4% [2013]) was observed. Local surveillance data reveal a distinct and dynamic distribution of respiratory viruses over the years. Data from published literature and abstracts show that influenza B is a significant cause of disease with an unpredictable circulation pattern and showing trends indicating reemergence of the B/Victoria lineage. The abstracts report notable levels of co-circulation of both influenza B lineages (2000-2013). Mismatch between the Southern hemisphere vaccine and the most prevalent circulating viruses in Brazil were observed in five influenza seasons. The evidence on co-circulation of two influenza B lineages and mismatched seasons in Brazil indicates the benefit of quadrivalent influenza vaccines in conferring broader seasonal influenza protection. Additionally, improving influenza surveillance platforms in Brazil is important for monitoring disease trends and the impact of introducing seasonal

  14. Patterns of influenza B circulation in Brazil and its relevance to seasonal vaccine composition.

    PubMed

    Barros, Eliana Nogueira Castro de; Cintra, Otavio; Rossetto, Erika; Freitas, Laís; Colindres, Romulo

    2016-01-01

    Data on the burden of disease and circulation patterns of influenza B lineages for Brazil are limited. This review aims to describe the pattern of influenza B occurrence in Brazil to have a better understanding of its epidemiology and its relevance when considering seasonal influenza vaccine composition. A review of the data including analysis of international and local surveillance data as well as information from online search of databases using Medical Subject Headings terms in conjunction with screening of abstracts from scientific events was performed. Based on international epidemiologic surveillance data, moderate levels of influenza B disease (19%; 2006-2014) were observed. Of these nine years, it was possible to compare data from three years (2007, 2008 and 2013) which have information on the circulating influenza B lineage. Co-circulation of influenza B lineages was observed in all these three influenza seasons, of which, during one season, a high degree of mismatch between the vaccine lineage and the predominant circulating lineage (91.4% [2013]) was observed. Local surveillance data reveal a distinct and dynamic distribution of respiratory viruses over the years. Data from published literature and abstracts show that influenza B is a significant cause of disease with an unpredictable circulation pattern and showing trends indicating reemergence of the B/Victoria lineage. The abstracts report notable levels of co-circulation of both influenza B lineages (2000-2013). Mismatch between the Southern hemisphere vaccine and the most prevalent circulating viruses in Brazil were observed in five influenza seasons. The evidence on co-circulation of two influenza B lineages and mismatched seasons in Brazil indicates the benefit of quadrivalent influenza vaccines in conferring broader seasonal influenza protection. Additionally, improving influenza surveillance platforms in Brazil is important for monitoring disease trends and the impact of introducing seasonal

  15. Surface circulation and upwelling patterns around Sri Lanka

    NASA Astrophysics Data System (ADS)

    de Vos, A.; Pattiaratchi, C. B.; Wijeratne, E. M. S.

    2013-09-01

    Sri Lanka occupies a unique location within the equatorial belt in the northern Indian Ocean with the Arabian Sea on its western side and the Bay of Bengal on its eastern side. The region is characterised by bi-annually reversing monsoon winds resulting from seasonal differential heating and cooling of the continental land mass and the ocean. This study explored elements of the dynamics of the surface circulation and coastal upwelling in the waters around Sri Lanka using satellite imagery and the Regional Ocean Modelling System (ROMS) configured to the study region and forced with ECMWF interim data. The model was run for 2 yr to examine the seasonal and shorter term (∼10 days) variability. The results confirmed the presence of the reversing current system in response to the changing wind field: the eastward flowing Southwest Monsoon Current (SMC) during the Southwest (SW) monsoon transporting 11.5 Sv and the westward flowing Northeast Monsoon Current (NMC) transporting 9.5 Sv during the Northeast (NE) monsoon, respectively. A recirculation feature located to the east of Sri Lanka during the SW monsoon, the Sri Lanka Dome, is shown to result from the interaction between the SMC and the Island of Sri Lanka. Along the eastern and western coasts, during both monsoon periods, flow is southward converging along the south coast. During the SW monsoon the Island deflects the eastward flowing SMC southward whilst along the east coast the southward flow results from the Sri Lanka Dome recirculation. The major upwelling region, during both monsoon periods, is located along the south coast and is shown to be due to flow convergence and divergence associated with offshore transport of water. Higher surface chlorophyll concentrations were observed during the SW monsoon. The location of the flow convergence and hence the upwelling centre was dependent on the relative strengths of wind driven flow along the east and west coasts: during the SW (NE) monsoon the flow along the

  16. Surface circulation and upwelling patterns around Sri Lanka

    NASA Astrophysics Data System (ADS)

    de Vos, A.; Pattiaratchi, C. B.; Wijeratne, E. M. S.

    2014-10-01

    Sri Lanka occupies a unique location within the equatorial belt in the northern Indian Ocean, with the Arabian Sea on its western side and the Bay of Bengal on its eastern side, and experiences bi-annually reversing monsoon winds. Aggregations of blue whale (Balaenoptera musculus) have been observed along the southern coast of Sri Lanka during the northeast (NE) monsoon, when satellite imagery indicates lower productivity in the surface waters. This study explored elements of the dynamics of the surface circulation and coastal upwelling in the waters around Sri Lanka using satellite imagery and numerical simulations using the Regional Ocean Modelling System (ROMS). The model was run for 3 years to examine the seasonal and shorter-term (~10 days) variability. The results reproduced correctly the reversing current system, between the Equator and Sri Lanka, in response to the changing wind field: the eastward flowing Southwest Monsoon Current (SMC) during the southwest (SW) monsoon transporting 11.5 Sv (mean over 2010-2012) and the westward flowing Northeast Monsoon Current (NMC) transporting 9.6 Sv during the NE monsoon, respectively. A recirculation feature located to the east of Sri Lanka during the SW monsoon, the Sri Lanka Dome, is shown to result from the interaction between the SMC and the island of Sri Lanka. Along the eastern and western coasts, during both monsoon periods, flow is southward converging along the southern coast. During the SW monsoon, the island deflects the eastward flowing SMC southward, whilst along the eastern coast, the southward flow results from the Sri Lanka Dome recirculation. The major upwelling region, during both monsoon periods, is located along the southern coast, resulting from southward flow converging along the southern coast and subsequent divergence associated with the offshore transport of water. Higher surface chlorophyll concentrations were observed during the SW monsoon. The location of the flow convergence and hence the

  17. Drought Variability in Eastern Part of Romania and its Connection with Large-Scale Air Circulation

    NASA Astrophysics Data System (ADS)

    Barbu, Nicu; Stefan, Sabina; Georgescu, Florinela

    2014-05-01

    Drought is a phenomenon that appears due to precipitation deficit and it is intensified by strong winds, high temperatures, low relative humidity and high insolation; in fact, all these factors lead to increasing of evapotranspiration processes that contribute to soil water deficit. The Standardized Precipitation Evapotranspiration Index (SPEI) take into account all this factors listed above. The temporal variability of the drought in Eastern part of Romania for 50 years, during the period 1961-2010, is investigated. This study is focused on the drought variability related to large scale air circulation. The gridded dataset with spatial resolution of 0.5º lat/lon of SPEI, (https://digital.csic.es/handle/10261/72264) were used to analyze drought periods in connection with large scale air circulation determinate from the two catalogues (GWT - GrossWetter-Typen and WLK - WetterLargenKlassifikation) defined in COST733Action. The GWT catalogue uses at input dataset the sea level pressure and the WLK catalogue uses as input dataset the geopotential field at 925 hPa and 500 hPa, wind at 700 hPa and total water content for entire atmospheric column. In this study we use the GWT catalogue with 18 circulation types and the WLK catalogue with 40 circulation types. The analysis for Barlad Hydrological Basin indicated that the negative values (that means water deficit - drought period) of SPEI are associated with prevailing anticyclonic regime and positive values (that means water excess - rainy period) of SPEI are associated with prevailing cyclonic regime as was expected. In last decade was observed an increase of dry period associated with an increase of anticyclonic activity over Romania. Using GWT18 catalogue the drought are associated with the north-eastern anticyclonic circulation type (NE-A). According to the WLK40 catalogue, the dominant circulation type associated with the drought is north-west-anticyclonic-dry anticyclonic (NW-AAD) type. keywords: drought, SPEI

  18. Wind-driven circulation patterns in a shallow estuarine lake: St Lucia, South Africa

    NASA Astrophysics Data System (ADS)

    Schoen, Julia H.; Stretch, Derek D.; Tirok, Katrin

    2014-06-01

    The spatiotemporal structure of wind-driven circulation patterns and associated water exchanges or residence times can drive important bio-hydrodynamic interactions in shallow lakes and estuaries. The St Lucia estuarine lake in South Africa is an example of such a system. It is a UNESCO World Heritage Site and RAMSAR wetland of international importance but no detailed research on its circulation patterns has previously been undertaken. In this study, a hydrodynamic model was used to investigate the structure of these circulations to provide insights into their role in transport and water exchange processes. A strong diurnal temporal pattern of wind speeds, together with directional switching between two dominant directions, drives intermittent water exchanges and mixing between the lake basins. “High speed flows in shallow nearshore areas with slower upwind counter-flows in deeper areas, linked by circulatory gyres, are key features of the circulation”. These patterns are strongly influenced by the complex geometry of St Lucia and constrictions in the system. Water exchange time scales are non-homogeneous with some basin extremities having relatively long residence times. The influence of the circulation patterns on biological processes is discussed.

  19. Global circulation patterns of seasonal influenza viruses vary with antigenic drift

    NASA Astrophysics Data System (ADS)

    Bedford, Trevor; Riley, Steven; Barr, Ian G.; Broor, Shobha; Chadha, Mandeep; Cox, Nancy J.; Daniels, Rodney S.; Gunasekaran, C. Palani; Hurt, Aeron C.; Kelso, Anne; Klimov, Alexander; Lewis, Nicola S.; Li, Xiyan; McCauley, John W.; Odagiri, Takato; Potdar, Varsha; Rambaut, Andrew; Shu, Yuelong; Skepner, Eugene; Smith, Derek J.; Suchard, Marc A.; Tashiro, Masato; Wang, Dayan; Xu, Xiyan; Lemey, Philippe; Russell, Colin A.

    2015-07-01

    Understanding the spatiotemporal patterns of emergence and circulation of new human seasonal influenza virus variants is a key scientific and public health challenge. The global circulation patterns of influenza A/H3N2 viruses are well characterized, but the patterns of A/H1N1 and B viruses have remained largely unexplored. Here we show that the global circulation patterns of A/H1N1 (up to 2009), B/Victoria, and B/Yamagata viruses differ substantially from those of A/H3N2 viruses, on the basis of analyses of 9,604 haemagglutinin sequences of human seasonal influenza viruses from 2000 to 2012. Whereas genetic variants of A/H3N2 viruses did not persist locally between epidemics and were reseeded from East and Southeast Asia, genetic variants of A/H1N1 and B viruses persisted across several seasons and exhibited complex global dynamics with East and Southeast Asia playing a limited role in disseminating new variants. The less frequent global movement of influenza A/H1N1 and B viruses coincided with slower rates of antigenic evolution, lower ages of infection, and smaller, less frequent epidemics compared to A/H3N2 viruses. Detailed epidemic models support differences in age of infection, combined with the less frequent travel of children, as probable drivers of the differences in the patterns of global circulation, suggesting a complex interaction between virus evolution, epidemiology, and human behaviour.

  20. Global circulation patterns of seasonal influenza viruses vary with antigenic drift.

    PubMed

    Bedford, Trevor; Riley, Steven; Barr, Ian G; Broor, Shobha; Chadha, Mandeep; Cox, Nancy J; Daniels, Rodney S; Gunasekaran, C Palani; Hurt, Aeron C; Kelso, Anne; Klimov, Alexander; Lewis, Nicola S; Li, Xiyan; McCauley, John W; Odagiri, Takato; Potdar, Varsha; Rambaut, Andrew; Shu, Yuelong; Skepner, Eugene; Smith, Derek J; Suchard, Marc A; Tashiro, Masato; Wang, Dayan; Xu, Xiyan; Lemey, Philippe; Russell, Colin A

    2015-07-01

    Understanding the spatiotemporal patterns of emergence and circulation of new human seasonal influenza virus variants is a key scientific and public health challenge. The global circulation patterns of influenza A/H3N2 viruses are well characterized, but the patterns of A/H1N1 and B viruses have remained largely unexplored. Here we show that the global circulation patterns of A/H1N1 (up to 2009), B/Victoria, and B/Yamagata viruses differ substantially from those of A/H3N2 viruses, on the basis of analyses of 9,604 haemagglutinin sequences of human seasonal influenza viruses from 2000 to 2012. Whereas genetic variants of A/H3N2 viruses did not persist locally between epidemics and were reseeded from East and Southeast Asia, genetic variants of A/H1N1 and B viruses persisted across several seasons and exhibited complex global dynamics with East and Southeast Asia playing a limited role in disseminating new variants. The less frequent global movement of influenza A/H1N1 and B viruses coincided with slower rates of antigenic evolution, lower ages of infection, and smaller, less frequent epidemics compared to A/H3N2 viruses. Detailed epidemic models support differences in age of infection, combined with the less frequent travel of children, as probable drivers of the differences in the patterns of global circulation, suggesting a complex interaction between virus evolution, epidemiology, and human behaviour.

  1. A comprehensive classification of anomalous circulation patterns responsible for persistent precipitation extremes in South China

    NASA Astrophysics Data System (ADS)

    Wu, Hui; Zhai, Panmao; Chen, Yang

    2016-06-01

    Based on observational precipitation at 63 stations in South China and NCEP-NCAR reanalysis data during 1951-2010, a cluster analysis is performed to classify large-scale circulation patterns responsible for persistent precipitation extremes (PPEs) that are independent of the influence of tropical cyclones (TCs). Conceptual schematics depicting configurations among planetary-scale systems at different levels are established for each type. The PPEs free from TCs account for 38.6% of total events, and they tend to occur during April-August and October, with the highest frequency observed in June. Corresponding circulation patterns during June-August can be mainly categorized into two types, i.e., summer-I type and summer-II type. In summer-I type, the South Asian high takes the form of a zonal-belt type. The axis of upstream westerly jets is northwest-oriented. At the middle level, the westerly jets at midlatitudes extend zonally. Along the southern edge of the westerly jet, synoptic eddies steer cold air to penetrate southward; the Bay of Bengal (BOB) trough is located to the north; a shallow trough resides over coastal areas of western South China; and an intensified western Pacific subtropical high (WPSH) extends westward. The anomalous moisture is mainly contributed by horizontal advection via southwesterlies around 20 °N and southeasterlies from the southern flange of the WPSH. Moisture convergence maximizes in coastal regions of eastern South China, which is the very place recording extreme precipitation. In summer-II type, the South Asian high behaves as a western-center type. The BOB trough is much deeper, accompanied by a cyclone to its north; and a lower-level trough appears in northwestern parts of South China. Different to summer-I type, moisture transport via southwesterlies is mostly responsible for the anomalous moisture in this type. The moisture convergence zones cover Guangdong, Guangxi, and Hainan, matching well with the areas of flooding. It is

  2. Spatial patterns of diagenesis during geothermal circulation in carbonate platforms

    USGS Publications Warehouse

    Wilson, A.M.; Sanford, W.; Whitaker, F.; Smart, P.

    2001-01-01

    Geothermal convection of seawater deep in carbonate platforms could provide the necessary supply of magnesium for dolomitization at temperatures high enough to overcome kinetic limitations. We used reactive-transport simulations to predict the rates and spatial patterns of dolomitization during geothermal convection in a platform that was 40 km across and 2 km thick. In the simulations, porosity and permeability decrease with depth to account for sediment compaction. Dolomitization of a platform consisting of medium grained (???0.05 mm) sediments occurred in a broad band ranging from ???2.5 km depth near the margin to ???1.5 km depth near the platform center. The area of dolomitization is deep enough that temperatures exceed ???50??C but not so deep that low permeabilities restrict mass transport. Complete dolomitization in the center of this zone is estimated to require at least 60 my. Incorporation of permeability contrasts, permeable beds, and reactive beds focused dolomitization strongly and reduced the estimated time required for dolomitization by as much as 50 percent. Dolomitization created magnesium-depleted, calcium-rich fluids in less than 10 ky, and results support a link between dolomitization and anhydrite precipitation where adequate sulfate is available.

  3. A Warm Spitzer Survey of Atmospheric Circulation Patterns

    NASA Astrophysics Data System (ADS)

    Knutson, Heather; Agol, E.; Burrows, A.; Charbonneau, D.; Cowan, N.; Deming, D.; Desert, J.; Fortney, J.; Kite, E.; Langton, J.; Laughlin, G.; Lewis, N.; Showman, A.

    2011-09-01

    The atmospheres of close-in extrasolar planets experience strong, asymmetrically distributed radiative forcing that can potentially lead to dramatic variations in both temperature and composition between the day- and night-side hemispheres. However, secondary eclipse observations only tell us about the properties of the dayside atmosphere, while transmission spectroscopy probes the region around the day-night terminator. By measuring changes in the infrared emission spectra of these planets as a function of orbital phase, we can resolve thermal and compositional gradients in these atmospheres, allowing us to obtain a complete picture of their local properties. The most extensively studied planet to date, HD 189733b, appears to have a relatively modest day-night temperature gradient as seen in the 8 and 24 micron Spitzer bands, suggesting that compositional gradients in this atmosphere are likely to be minimal. We present new, full-orbit phase curves at 3.6 and 4.5 um obtained with warm Spitzer, which we use to construct improved multi-color maps and to constrain variations in the pressure-temperature profile and atmospheric composition as a function of longitude. We also present preliminary results for complementary full-orbit observations of HAT-P-7b in the same bands, and discuss an emerging pattern in which the most highly irradiated (>2000 K) planets appear to undergo a shift towards large day-night temperature gradients, perhaps due to Lorentz braking or other MHD processes.

  4. Long-term air temperature variation in the Karkonosze mountains according to atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Migała, Krzysztof; Urban, Grzegorz; Tomczyński, Karol

    2016-07-01

    The results of meteorological measurements carried out continuously on Mt Śnieżka in Karkonosze mountains since 1880 well document the warming observed on a global scale. Data analysis indicates warming expressed by an increase in the mean annual air temperature of 0.8 °C/100 years. A much higher temperature increase was recorded in the last two decades at the turn of the twenty-first century. Mean decade air temperatures increased from -0.1 to 1.5 °C. It has been shown that there are relationships between air temperature at Mt Śnieżka and global mechanisms of atmospheric and oceanic circulation. Thermal conditions of the Karkonosze (Mt Śnieżka) accurately reflect global climate trends and impact of the North Atlantic Oscillation (NAO) index, macrotypes of atmospheric circulation in Europe (GWL) and Atlantic Multidecadal Oscillation (AMO). The increase in air temperature during the 1989-2012 solar magnetic cycle may reveal a synergy effect to which astrophysical effects and atmospheric and oceanic circulation effects contribute, modified by constantly increasing anthropogenic factors.

  5. Montane ecosystem productivity responds more to global circulation patterns than climatic trends

    NASA Astrophysics Data System (ADS)

    Desai, A. R.; Wohlfahrt, G.; Zeeman, M. J.; Katata, G.; Eugster, W.; Montagnani, L.; Gianelle, D.; Mauder, M.; Schmid, H.-P.

    2016-02-01

    Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies.

  6. EVALUATION OF GROUNDWATER FLOW PATTERNS AROUND A DUAL-SCREENED GROUNDWATER CIRCULATION WELL

    EPA Science Inventory

    Dual-screened groundwater circulation wells (GCWs) can be used to remove contaminant mass and to mix reagents in situ. GCWs are so named because they force water in a circular pattern between injection and extraction screens. The radial extent, flux and direction of the effective...

  7. Evaluating the potential of Iberian lakes as sensors of climate circulation patterns

    NASA Astrophysics Data System (ADS)

    Hernández, Armand; Trigo, Ricardo M.; Jerez, Sonia; Rico-Herrero, Maria T.; Vega, José C.; Jambrina-Enríquez, Margarita; Valero-Garcés, Blas L.; Giralt, Santiago

    2013-04-01

    Lakes are one of the best continental sensors for reconstructing past environmental and climatic changes. Recent lacustrine systems may be used for reconstructing with high-temporal resolution past climate parameters (e.g. precipitation, temperature, wind), land management changes and limnological conditions such as pH, salinity, or nutrients concentrations using a large set of techniques and proxies. Paleoenvironmental reconstructions can be improved by validating them with instrumental data, and the availability of monitoring data greatly enhances the potential of lakes to evaluate the link between the measured physical-chemical-biological parameters and the indicators from lake sediments. The Iberian Peninsula (IP) is an excellent site to conduct quantitative climate reconstructions owing to its location between the Eurosiberian and Mediterranean regions. Due to its geographic position, a large fraction of the IP climate is dominated by the most important large scale pattern of the Northern Hemisphere, i.e. the North Atlantic Oscillation (NAO). However, a number of recent works has put into evidence that besides the NAO mode there are other relevant atmospheric circulation patterns over the North Atlantic and European sector that play an important role in terms of Western Mediterranean climate. Among these we have evaluated particularly the so-called Scandinavian (SCAND) and eastern Atlantic (EA) which have commonly been overlooked. Monthly limnological monitoring in Lake Sanabria (42°07'N, 06°43'W) and Lake Las Madres (40°18'N, 3°31'W) since 1986 and 1991, respectively, provided a unique opportunity to test the spatio-temporal relationships between meteorological data and climate modes, hydrology, lake dynamics and, in the Lake Sanabria case, how the climate signal is transferred to the lake sediments. For this purpose, we have used five complementary datasets: (1) meteorological (air temperature, total precipitation and wind intensity), (2) climate modes

  8. Utilization of ventilation air methane as a supplementary fuel at a circulating fluidized bed combustion boiler.

    PubMed

    You, Changfu; Xu, Xuchang

    2008-04-01

    Ventilation air methane (VAM) accounts for 60-80% of the total emissions from coal mining activities in China, which is of serious greenhouse gas concerns as well as a waste of valuable fuel sources. This contribution evaluates the use of the VAM utilization methods as a supplementary fuel at a circulating fluidized bed combustion boiler. The paper describes the system design and discusses some potential technical challenges such as methane oxidation rate, corrosion, and efficiency. Laboratory experimentation has shown that the VAM can be burnt completely in circulated fluidized bed furnaces, and the VAM oxidation does not obviously affect the boiler operation when the methane concentration is less than 0.6%. The VAM decreased the incomplete combustion loss for the circulating fluidized bed combustion furnace. The economic benefit from the coal saving insures that the proposed system is more economically feasible.

  9. Regional climates in the GISS general circulation model: Surface air temperature

    NASA Technical Reports Server (NTRS)

    Hewitson, Bruce

    1994-01-01

    One of the more viable research techniques into global climate change for the purpose of understanding the consequent environmental impacts is based on the use of general circulation models (GCMs). However, GCMs are currently unable to reliably predict the regional climate change resulting from global warming, and it is at the regional scale that predictions are required for understanding human and environmental responses. Regional climates in the extratropics are in large part governed by the synoptic-scale circulation and the feasibility of using this interscale relationship is explored to provide a way of moving to grid cell and sub-grid cell scales in the model. The relationships between the daily circulation systems and surface air temperature for points across the continental United States are first developed in a quantitative form using a multivariate index based on principal components analysis (PCA) of the surface circulation. These relationships are then validated by predicting daily temperature using observed circulation and comparing the predicted values with the observed temperatures. The relationships predict surface temperature accurately over the major portion of the country in winter, and for half the country in summer. These relationships are then applied to the surface synoptic circulation of the Goddard Institute for Space Studies (GISS) GCM control run, and a set of surface grid cell temperatures are generated. These temperatures, based on the larger-scale validated circulation, may now be used with greater confidence at the regional scale. The generated temperatures are compared to those of the model and show that the model has regional errors of up to 10 C in individual grid cells.

  10. Influence of atmospheric circulation patterns on local cloud and solar variability in Bergen, Norway

    NASA Astrophysics Data System (ADS)

    Parding, Kajsa; Olseth, Jan Asle; Liepert, Beate G.; Dagestad, Knut-Frode

    2016-08-01

    In a previous paper, we have shown that long-term cloud and solar observations (1965-2013) in Bergen, Norway (60.39°N, 5.33°E) are compatible with a largely cloud dominated radiative climate. Here, we explicitly address the relationship between the large scale circulation over Europe and local conditions in Bergen, identifying specific circulation shifts that have contributed to the observed cloud and solar variations. As a measure of synoptic weather patterns, we use the Grosswetterlagen (GWL), a daily classification of European weather for 1881-2013. Empirical models of cloud cover, cloud base, relative sunshine duration, and normalised global irradiance are constructed based on the GWL frequencies, extending the observational time series by more than 70 years. The GWL models successfully reproduce the observed increase in cloud cover and decrease in solar irradiance during the 1970s and 1980s. This cloud-induced dimming is traced to an increasing frequency of cyclonic and decreasing frequency of anticyclonic weather patterns over northern Europe. The changing circulation patterns in winter can be understood as a shift from the negative to the positive phase of the North Atlantic and Arctic Oscillation. A recent period of increasing solar irradiance is observed but not reproduce by the GWL models, suggesting this brightening is associated with factors other than large scale atmospheric circulation, possibly decreasing aerosol loads and local cloud shifts.

  11. Relationship between climate extremes in Romania and their connection to large-scale air circulation

    NASA Astrophysics Data System (ADS)

    Barbu, Nicu; Ştefan, Sabina

    2015-04-01

    The aim of this paper is to investigate the connection between climate extremes (temperature and precipitation) in Romania and large-scale air circulation. Daily observational data of maximum air temperature and amount of precipitation for the period 1961-2010 were used to compute two seasonal indices associated with temperature and precipitation, quantifying their frequency, as follows: frequency of very warm days (FTmax90 ≥ 90th percentile), frequency of very wet days (FPp90; daily precipitation amount ≥ 90th percentile). Seasonally frequency of circulation types were calculated from daily circulation types determined by using two objective catalogues (GWT - GrossWetter-Typen and WLK - WetterLargenKlassifikation) from the COST733Action. Daily reanalysis data sets (sea level pressure, geopotential height at 925 and 500 hPa, u and v components of wind vector at 700 hPa and precipitable water content for the entire atmospheric column) build up by NCEP/NCAR, with 2.5°/2.5° lat/lon spatial resolution, were used to determine the circulation types. In order to select the optimal domain size related to the FTmax90 and the FPp90, the explained variance (EV) has been used. The EV determines the relation between the variance among circulation types and the total variance of the variable under consideration. This method quantifies the discriminatory power of a classification. The relationships between climate extremes in Romania and large-scale air circulation were investigated by using multiple linear regression model (MLRM), the predictands are FTmax90 and FPp90 and the circulation types were used as predictors. In order to select the independent predictors to build the MLRM the collinearity and multicollinearity analysis were performed. The study period is dividend in two periods: the period 1961-2000 is used to train the MLRM and the period 2001-2010 is used to validate the MLRM. The analytical relationship obtained by using MLRM can be used for future projection

  12. The Use of Print Materials in the Internet Age: A Comparative Study of Academic Library Circulation Patterns

    ERIC Educational Resources Information Center

    Haley, Daniel Joseph

    2010-01-01

    The circulation records from 1997/98 to 2007/08 for UCLA and from 2000/01 to 2007/08 for Pasadena City College (PCC) were analyzed to examine patterns in the use of print materials during a period of increasingly available online digital information resources. The analysis included examinations of longitudinal circulation patterns broken down by…

  13. Association between atmospheric circulation patterns and firn-ice core records from the Inilchek glacierized area, central Tien Shan, Asia

    USGS Publications Warehouse

    Aizen, V.B.; Aizen, E.M.; Melack, J.M.; Kreutz, K.J.; Cecil, L.D.

    2004-01-01

    Glacioclimatological research in the central Tien Shan was performed in the summers of 1998 and 1999 on the South Inilchek Glacier at 5100-5460 m. A 14.36 m firn-ice core and snow samples were collected and used for stratigraphic, isotopic, and chemical analyses. The firn-ice core and snow records were related to snow pit measurements at an event scale and to meteorological data and synoptic indices of atmospheric circulation at annual and seasonal scales. Linear relationships between the seasonal air temperature and seasonal isotopic composition in accumulated precipitation were established. Changes in the ??18O air temperature relationship, in major ion concentration and in the ratios between chemical species, were used to identify different sources of moisture and investigate changes in atmospheric circulation patterns. Precipitation over the central Tien Shan is characterized by the lowest ionic content among the Tien Shan glaciers and indicates its mainly marine origin. In seasons of minimum precipitation, autumn and winter, water vapor was derived from the and and semiarid regions in central Eurasia and contributed annual maximal solute content to snow accumulation in Tien Shan. The lowest content of major ions was observed in spring and summer layers, which represent maximum seasonal accumulation when moisture originates over the Atlantic Ocean and Mediterranean and Black Seas. Copyright 2004 by the American Geophysical Union.

  14. Global circulation patterns of seasonal influenza viruses vary with antigenic drift

    PubMed Central

    Bedford, Trevor; Riley, Steven; Barr, Ian G.; Broor, Shobha; Chadha, Mandeep; Cox, Nancy J.; Daniels, Rodney S.; Gunasekaran, C. Palani; Hurt, Aeron C.; Kelso, Anne; Lewis, Nicola S.; Li, Xiyan; McCauley, John W.; Odagiri, Takato; Potdar, Varsha; Rambaut, Andrew; Shu, Yuelong; Skepner, Eugene; Smith, Derek J.; Suchard, Marc A.; Tashiro, Masato; Wang, Dayan; Xu, Xiyan; Lemey, Philippe; Russell, Colin A.

    2015-01-01

    Understanding the spatio-temporal patterns of emergence and circulation of new human seasonal influenza virus variants is a key scientific and public health challenge. The global circulation patterns of influenza A/H3N2 viruses are well-characterized1-7 but the patterns of A/H1N1 and B viruses have remained largely unexplored. Here, based on analyses of 9,604 hemagglutinin sequences of human seasonal influenza viruses from 2000–2012, we show that the global circulation patterns of A/H1N1 (up to 2009), B/Victoria, and B/Yamagata viruses differ substantially from those of A/H3N2 viruses. While genetic variants of A/H3N2 viruses did not persist locally between epidemics and were reseeded from East and Southeast (E-SE) Asia, genetic variants of A/H1N1 and B viruses persisted across multiple seasons and exhibited complex global dynamics with E-SE Asia playing a limited role in disseminating new variants. The less frequent global movement of influenza A/H1N1 and B viruses coincided with slower rates of antigenic evolution, lower ages of infection, and smaller less frequent epidemics compared to A/H3N2 viruses. Detailed epidemic models support differences in age of infection, combined with the less frequent travel of children, as likely drivers of the differences in the patterns of global circulation, suggesting a complex interaction between virus evolution, epidemiology and human behavior. PMID:26053121

  15. Quantifying the effects of mixing and residual circulation on trends of stratospheric mean age of air

    NASA Astrophysics Data System (ADS)

    Ploeger, Felix; Abalos, Marta; Birner, Thomas; Konopka, Paul; Legras, Bernard; Müller, Rolf; Riese, Martin

    2015-04-01

    Trends in stratospheric mean age of air are driven both by changes in the (slow, large scale) residual mean mass circulation and by changes in (fast, locally acting) eddy mixing. However, to what degree both effects affect mean age trends is an open question. Here, we present a method that allows the effects of mixing and residual circulation on trends of mean age of air to be quantified. This method is based on mean age simulations with the Lagrangian chemistry transport model CLaMS driven by ERA-Interim reanalysis, and on the mean age tracer continuity equation integrated along the residual circulation. CLaMS simulated climatological mean age in the lower stratosphere shows reliable agreement with balloon borne in-situ obsevations and with satellite observations by MIPAS (Michelson Interferometer for Passive Atmospheric Sounding). During 1990--2013, CLaMS simulated mean age decreases throughout most of the stratosphere, qualitatively consistent with results based on climate model simulations (e.g., Butchart et al., 2010). Remarkably, in the Northern hemisphere subtropics and mid-latitudes above about 24km CLaMS mean age trends are insignificant, consistent with published mean age trends from in-situ observations (Engel et al., 2009). Furthermore, during 2002--2012 CLaMS mean age changes show a clear hemispheric asymmetry in agreement with MIPAS satellite observations (Stiller et al., 2012; Ploeger et al., 2014) and HCl decadal changes (Mahieu et al., 2014). We find that changes in the transit time along the residual circulation alone cannot explain the mean age trends, and including the effect of mixing integrated along the air parcel history is essential. Therefore, differences in mean age trends between models or between models and observations are likely related to differences in the integrated effect of mixing on mean age of air. Above about 550K, trends in the integrated mixing effect appear to be likely coupled to residual circulation changes. References

  16. Baltic Sea Ice Regional Indices and their relationship with atmospheric circulation patterns and maritime navigation

    NASA Astrophysics Data System (ADS)

    Sztobryn, M.; Kowalska, B.

    2009-04-01

    The Baltic navigation and urban activities of the coastal communities around the Baltic Sea depended always very much on the ice conditions in the sea. The sea ice occurs different in form and amount, depending on the sea area and the winter season. The aim of the work was the investigation of influence of atmospheric circulation patterns on sea ice condition of Baltic Sea (by the sea ice regional indices). The atmospheric circulation patterns were represented by the German Weather Service's - Grosswetterlagen. The relationship between the ice severity indices and icebreakers activities (number of cases, in which the Swedish and Finnish icebreakers assisted the ships) were investigated. The work was done under the Seaman project (Norwegian Financial Mechanism)

  17. Abrupt shutdown of the Atlantic meridional overturning circulation and rainfall patterns in Mexico

    NASA Astrophysics Data System (ADS)

    Martinez-Lopez, B.; Garcia, C. Gay

    2010-03-01

    Abrupt shutdown of the Atlantic meridional overturning circulation and rainfall patterns in Mexico. Model simulations agree that the warming and the resulting freshening of the surface waters will significantly reduce deep water formation in the Labrador Sea during the next decades. A complete collapse of the Atlantic meridional overturning circulation (AMOC) would be associated with a strong cooling of several degrees in the North Atlantic region (Winton 2003). The future response of the AMOC, however, is predictable only within a broad range due to the existence of a critical threshold in the system and the large uncertainty about both the location of this threshold on the freshwater axis and the freshwater forcing (Zickfeld et al., 2007). According to Meehl et al. (2007), the probability of an abrupt slowdown or shutdown of the AMOC triggered by greenhouse gas forcing is low, but it is considered a high-impact event (Wood et al., 2003). An abrupt change in the AMOC could occur so unexpectedly and quickly that natural systems would have difficulty adapting to them (NRC, 2002). In this work we use coupled ocean-atmosphere models to asses the response of rainfall patterns in Mexico to an abrupt shutdown of the AMOC. First, a cooling pattern, triggered by a freshwater flux perturbation in the North Atlantic, is simulated by an isopycnic ocean model coupled to an atmospheric energy balance model. Then, this anomalous surface temperature pattern is used as a surface boundary condition for a numerical experiment performed using the simplified global atmospheric circulation model PUMA (Portable University Model of the Atmosphere; Fraedrich et al., 1998), which compute the perturbed rainfall patterns in Mexico.

  18. Patterns of Local Circulation in the Itaipu Lake Area: Numerical Simulations of Lake Breeze.

    NASA Astrophysics Data System (ADS)

    Stivari, Sônia M. S.; de Oliveira, Amauri P.; Karam, Hugo A.; Soares, Jacyra

    2003-01-01

    The lake-breeze circulation in the Itaipu region was investigated numerically using a nonhydrostatic version of the Topographic Vorticity Model. The area of study corresponds to a 100 km × 180 km rectangle, located on the Brazil-Paraguay border, with Itaipu Lake in its center. The characteristics of the lake breeze generated by the numerical experiments were consistent with the observations available in the area. The numerical experiments have shown that the land use effect is important in the spatial distribution of the lake-breeze circulation and that the topography contributes to modulating the breeze intensity, with the daytime valley-mountain circulation intensifying the lake breeze. However, the circulation pattern observed during daytime over the region is mainly due to the Itaipu Lake presence. The numerical results indicated that Itaipu Lake is able to generate and sustain a lake breeze, with 3.5 m s1 of maximum intensity and 1500-m depth, that propagates inland at 5.1 km h1 under typical undisturbed and calm-wind summer conditions.

  19. Tracking air-dropped drogues and dyes from aircraft in support of ERTS-1 circulation studies. [Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator); Davis, G.; Wang, H.

    1974-01-01

    The author has identified the following significant results. For two years ERTS-1 has been employed to investigate current circulation patterns in Delaware Bay under different tidal, flow, and wind conditions. Since sufficient numbers of current meters and boats are not available, air-droppable drogues and dye packs have been developed and tested. The drogues consist of a styrofoam float and a line to which is attached a stainless steel biplane. The length of the line determines at what depth currents will be monitored. The floats are color coded to distinguish their movement and mark the depth of the biplanes. Simultaneously floating and anchored dye packs of fluorescein dye have been deployed from aircraft. The movement of the dye and drogues is tracked by sequential aerial photography, using fixed markers on shore or on buoys as reference points to calibrate the scale and direction of drogue movement. The current data obtained by this technique is then used to annotate current circulation maps derived from ERTS-1 imagery.

  20. Determining the influence of different atmospheric circulation patterns on PM10 chemical composition in a source apportionment study

    NASA Astrophysics Data System (ADS)

    Masiol, Mauro; Squizzato, Stefania; Ceccato, Daniele; Rampazzo, Giancarlo; Pavoni, Bruno

    2012-12-01

    This study combines a set of chemometric analyses with a source apportionment model for discriminating the weather conditions, local processes and remote contributions having an impact on particulate matter levels and chemical composition. The proposed approach was tested on PM10 data collected in a semi-rural coastal site near Venice (Italy). The PM10 mass, elemental composition and the water soluble inorganic ions were quantified and seven sources were identified and apportioned using the positive matrix factorization: sea spray, aged sea salt, mineral dust, mixed combustions, road traffic, secondary sulfate and secondary nitrate. The influence of weather conditions on PM10 composition and its sources was investigated and the importance of air temperature and relative humidity on secondary components was evaluated. Samples collected in days with similar atmospheric circulation patterns were clustered on the basis of wind speed and direction. Significant differences in PM10 levels and chemical composition pointed out that the production of sea salt is strongly depending on the intensity of local winds. Differently, typical primary pollutants (i.e. from combustion and road traffic) increased during slow wind regimes. External contributions were also investigated by clustering the backward trajectories of air masses. The increase of combustion and traffic-related pollutants was observed when air masses originated from Central and Northwestern Europe and secondary sulfate was observed to rise when air masses had passed over the Po Valley. Conversely, anthropogenic contributions dropped when the origin was in the Mediterranean area and Northern Europe. The chemometric approach adopted can discriminate the role local and external sources play in determining the level and composition of airborne particulate matter and points out the weather circumstances favoring the worst pollution conditions. It may be of significant help in designing local and national air pollution

  1. Impacts of four northern-hemisphere teleconnection patterns on atmospheric circulations over Eurasia and the Pacific

    NASA Astrophysics Data System (ADS)

    Gao, Tao; Yu, Jin-yi; Paek, Houk

    2016-05-01

    The impacts of four teleconnection patterns on atmospheric circulation components over Eurasia and the Pacific region, from low to high latitudes in the Northern Hemisphere (NH), were investigated comprehensively in this study. The patterns, as identified by the Climate Prediction Center (USA), were the East Atlantic (EA), East Atlantic/Western Russia (EAWR), Polar/Eurasia (POLEUR), and Scandinavian (SCAND) teleconnections. Results indicate that the EA pattern is closely related to the intensity of the subtropical high over different sectors of the NH in all seasons, especially boreal winter. The wave train associated with this pattern serves as an atmospheric bridge that transfers Atlantic influence into the low-latitude region of the Pacific. In addition, the amplitudes of the EAWR, SCAND, and POLEUR patterns were found to have considerable control on the "Vangengeim-Girs" circulation that forms over the Atlantic-Eurasian region in winter or spring. The EA and EAWR mainly affect the westerlies in winter and spring and the POLEUR and SCAND, respectively, in summer and winter. Strong westerlies confine the extension of the North Polar vortex, which generally results in a small weak vortex and a shallow East Asian trough located in a position further east than normal. Furthermore, the North Polar vortex presents significant connections with the patterns during winter and summer. Analyses in this work suggest that the teleconnection patterns in summer could be driven, at least partly, by the Atlantic Multidecadal Oscillation, which to some degree might transmit the influence of the Atlantic Ocean to Eurasia and the Pacific region.

  2. Numerical simulation of temperature-driven air circulation and oxygen transport in unsaturated porous media

    SciTech Connect

    Guo, Weixing; Parizek, R.R. . Dept. of Geosciences)

    1992-01-01

    Temperature-driven air circulation within unsaturated porous media is receiving increasing attention in the studies of volatile organic component transport and remediation, safety assessment of radioactive waste repositories, soil moisture redistribution, etc. This coupled physical process also plays an important role in supplying oxygen to coal mine spoil where acid mine drainage is generated. To investigate the availability of oxygen within mine spoil, as the primary oxidant in acid reactions, a transient two-dimensional numerical model (HOT) which incorporates temperature-driven air circulation, dispersion-advection oxygen transport in gas phase, steady-state groundwater flow and chemical reactions, has been created. Energy and mass transfer across liquid and gas phases are included. Shrinking core models are used to simulate the kinetics of acid reactions. The rates of heat generation and oxygen consumption are determined stoichiometrically. The generalized Newton-Raphson method is used to linearize the partial differential equations describing heat and mass transfer in porous media. HOT has been used in studies of acid mine drainage generation within coal mine spoil and successfully compared with in-situ temperature measurements. This model may also be applied for some other research including soil vapor extraction, radon migration in soils and temperature prediction of nuclear waste repositories within unsaturated rocks.

  3. Computer mapping of turbidity and circulation patterns in Saginaw Bay, Michigan from LANDSAT data

    NASA Technical Reports Server (NTRS)

    Rogers, R. H. (Principal Investigator); Reed, L. E.; Smith, V. E.

    1975-01-01

    The author has identified the following significant results. LANDSAT was used as a basis for producing geometrically-corrected, color-coded imagery of turbidity and circulation patterns in Saginaw Bay, Michigan (Lake Huron). This imagery shows nine discrete categories of turbidity, as indicated by nine Secchi depths between 0.3 and 3.3 meters. The categorized imagery provided an economical basis for extrapolating water quality parameters from point samples to unsample areas. LANDSAT furnished a synoptic view of water mass boundaries that no amount of ground sampling or monitoring could provide.

  4. Pressure distributions and oil-flow patterns for a swept circulation-control wing

    NASA Technical Reports Server (NTRS)

    Keener, Earl R.; Sanderfer, Dwight T.; Wood, Norman J.

    1987-01-01

    Pressure distributions and photographs of oil flow patterns are presented for a circulation control wing. The model was an aspect ratio four semispan wing mounted on the side wall of the NASA Ames Transonic Wind Tunnel. The airfoil was a 20 percent thick ellipse, modified with circular leading and trailing edges of 4 percent radius, and had a 25.4 cm constant chord. This configuration does not represent a specific wing design, but is generic. A full span, tangetial, rearward blowing, circulation control slot was incorporated ahead of the trailing edge on the upper surface. The wing was tested at Mach numbers from 0.3 to 0.75 at sweep angle of 0 to 45 deg with internal to external pressure ratios of 1.0 to 3.0. Lift and pitching momemt coefficients were obtained from measured pressure distributions at five span stations. When the conventional corrections resulting from sweep angle are applied to the lift and moment of circulation control sections, no additional corrections are necessary to account for changes in blowing efficiency. This is demonstrated for an aft sweep angle of 45 deg. An empirical technique for estimating the downwash distribution of a swept wing was validated.

  5. Ground level air convection produces frost damage patterns in turfgrass.

    PubMed

    Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns. PMID:25796203

  6. Ground level air convection produces frost damage patterns in turfgrass.

    PubMed

    Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

  7. Ground level air convection produces frost damage patterns in turfgrass

    NASA Astrophysics Data System (ADS)

    Ackerson, Bruce J.; Beier, Richard A.; Martin, Dennis L.

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass ( Cynodon species Rich.), zoysiagrass ( Zoysia species Willd.), and buffalograss [ Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

  8. Linking storm surge activity and circulation variability along the Spanish coast through a synoptic pattern classification

    NASA Astrophysics Data System (ADS)

    Rasilla Álvarez, Domingo; Garcia Codrón, Juan Carlos

    2010-05-01

    The potentially negative consequences resulting from the estimations of global sea level rising along the current century are a matter of serious concern in many coastal areas worldwide. Most of the negative consequences of the sea level variability, such as flooding or erosion, are linked to episodic events of strong atmospheric forcing represented by deep atmospheric disturbances, especially if they combine with extreme astronomical high tides. Moreover, the interaction between the prevailing flows during such events and the actual orientation of the coast line might accelerate or mitigate such impacts. This contribution analyses sea surge variations measured at five tide-gauge stations located around the Iberian Peninsula and their relationships with regional scale circulation patterns with local-scale winds. Its aim is to improve the knowledge of surge related-coastal-risks by analysing the relationship between surges and their atmospheric forcing factors at different spatial scales. The oceanographic data set consists of hourly data from 5 tide gauge stations (Santander, Vigo, Bonanza, Málaga, Valencia and Barcelona) disseminated along the Spanish coastline, provided by Puertos del Estado. To explore the atmospheric mechanisms responsible for the sign and magnitude of sea surges, a regional Eulerian approach (a synoptic typing) were combined with a larger-scale Lagrangian method, based on the analysis of storm-tracks over the Atlantic and local information (synop reports) obtained from the closest meteorological stations to the tide gauges. The synoptic catalogue was obtained following a procedure that combines Principal Component Analysis (PCA) for reduction purposes and clustering (Ward plus K-means) to define the circulation types. Sea level pressure, surface 10m U and V wind components gridded data were obtained from NCEP Reanalysis, while storm tracks and cyclone statistics were extracted from the CDC Map Room Climate Products Storm Track Data (http

  9. Investigation of the role of large-scale circulation patterns on Central European streamflow

    NASA Astrophysics Data System (ADS)

    Steirou, Eva; Apel, Heiko; Merz, Bruno

    2016-04-01

    Large scale oscillations-phenomena such as El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) influence the climate and hydrological variables (temperature, precipitation, streamflow) in many areas around the globe. Here we review previous studies examining links between such phenomena and streamflow in Central Europe. The selected area under examination is the region covered by 9 countries: Germany, Poland, Switzerland, Lichtenstein, Austria, the Czech Republic, Slovakia, Hungary and Slovenia. The study takes into consideration only measured and not proxy data. Mean, low and high flows are examined separately in order to improve the understanding on the possible different influences of the climatic phenomena on different streamflow characteristics. Previous results form a consistent pattern that suggests causal relationships but only for certain indices and seasons. Most promising results concern the winter NAO index which seems to affect winter and spring streamflow in Central Europe and synoptic circulation patterns that have been linked to streamflow in the area throughout the year. Based on the findings of the review, we examine further the relations between NAO, synoptic circulation patterns and streamflow in the winter and spring season. In our analysis we examine 68 streamflow stations in Germany all covering the period 1932 to 2005. The investigation focuses on the interplay between NAO and synoptic patterns and on the effects of the climatic indices on the amplitude, spatial coherence and distributions of streamflow data. The preliminary results suggest that NAO weakly influences streamflow in both seasons and that a combined analysis with other climatic parameters may clarify possible existing links.

  10. Simulation of tidal flow and circulation patterns in the Loxahatchee River Estuary, southeastern Florida

    USGS Publications Warehouse

    Russell, G.M.; Goodwin, C.R.

    1987-01-01

    Results of a two-dimensional, vertically averaged, computer simulation model of the Loxahatchee River estuary show that under typical low freshwater inflow and vertically well mixed conditions, water circulation is dominated by freshwater inflow rather than by tidal influence. The model can simulate tidal flow and circulation in the Loxahatchee River estuary under typical low freshwater inflow and vertically well mixed conditions, but is limited, however, to low-flow and well mixed conditions. Computed patterns of residual water transport show a consistent seaward flow from the northwest fork through the central embayment and out Jupiter Inlet to the Atlantic Ocean. A large residual seaward flow was computed from the North Intracoastal Waterway to the inlet channel. Although the tide produces large flood and ebb flows in the estuary, tide-induced residual transport rates are low in comparison with freshwater-induced residual transport. Model investigations of partly mixed or stratified conditions in the estuary need to await development of systems capable of simulating three-dimensional flow patterns. (Author 's abstract)

  11. The Winter Atmospheric Circulation Patterns and their relationship with precipitation variability in Iran

    NASA Astrophysics Data System (ADS)

    Fattahi, E.; Sedaghatkerdar, A.

    2009-04-01

    To classify the atmospheric circulation patterns over Iran the sea level pressure and 500 hpa geopotential height for December-February of 1961-2003 was retrieved from NCEP/NCAR and used as input variables. By applying the S-mode principle component analysis (PCA) on daily composite of 500 hpa we reduced the data matrix (3880*408) to 11 components. The identified components were then rotated using varimax method in order to obtain simpler structure. The ward clustering algorithm was then used to classify studied days based on time variability of PC scores. So, by applying Ward clustering on resultant PC scores we grouped all days into 8 weather types. The relationship between frequency of various weather types and precipitation variability over Iran was investigated using correlation analysis. Moreover, the occurrences of precipitation during warm, cold and neutral phases of ENSO were also linked to the identified weather types. The results reveal that the Mediterranean low, Sub-polar low, Eastern high pressure, North high pressure and East European high pressure and also the combination of Siberian and European high pressures have the highest frequencies during El Nino periods, Whereas the Siberian high pressure and central high pressure systems are more frequent in La Nina periods. Keywords: Atmospheric circulation Patterns, principal component analysis, cluster analysis, ENSO, Iran.

  12. The sensitivity of latent heat flux to the air humidity approximations used in ocean circulation models

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, Pearn P.

    1990-01-01

    In deriving the surface latent heat flux with the bulk formula for the thermal forcing of some ocean circulation models, two approximations are commonly made to bypass the use of atmospheric humidity in the formula. The first assumes a constant relative humidity, and the second supposes that the sea-air humidity difference varies linearly with the saturation humidity at sea surface temperature. Using climatological fields derived from the Marine Deck and long time series from ocean weather stations, the errors introduced by these two assumptions are examined. It is shown that the errors reach above 100 W/sq m over western boundary currents and 50 W/sq m over the tropical ocean. The two approximations also introduce erroneous seasonal and spatial variabilities with magnitudes over 50 percent of the observed variabilities.

  13. Large-scale circulation patterns, instability factors and global precipitation modeling as influenced by external forcing

    NASA Astrophysics Data System (ADS)

    Bundel, A.; Kulikova, I.; Kruglova, E.; Muravev, A.

    2003-04-01

    Northern Atlantic when the real SSTs were used. Blocking structures in the circulation caused decreasing precipitation amounts. The wavelet approach gave a more distinctive discrimination in the modeled circulation and precipitation patterns versus different external forcing than a number of other statistical techniques. Several atmospheric instability indices (e.g. the Phillips like parameters, Richardson number etc) were additionally used in post-processing for a more detailed validation of the modeled large-scale and total precipitation amounts. It was shown that a reasonable variety of instability indices must be used for such validations and for precipitation output corrections. Their statistical stability may be substantiated only on the ensemble modeling basis. This work was performed with the financial support of the Russian Foundation for Basic Research (02-05-64655).

  14. Changes in atmospheric circulation patterns affect midcontinent wetlands sensitive to climate

    USGS Publications Warehouse

    LaBaugh, J.W.; Winter, T.C.; Swanson, G.A.; Rosenberry, D.

    1996-01-01

    Twenty-seven years of data from midcontinent wetlands indicate that the response of these wetlands to extremes in precipitation-drought and deluge-persists beyond the extreme events. Chemical changes transcend such simple relations as increased salinity during dry periods because drought provides mechanisms for removal of salt by deflation and seepage to groundwater. Inundation of vegetation zones including rooted or floating mats of cattail (Typha glauca) can stimulate sulfate reduction and shift the anion balance from sulfate to bicarbonate dominance. Disruptions in the circulation of moisture-laden air masses over the midcontinent, as in the drought of 1988 and the deluge of 1993, have a major effect on these wetlands, which are representatives of the primary waterfowl breeding habitat of the continent.

  15. Relationships between large-scale circulation patterns and carbon dioxide exchange by a deciduous forest

    NASA Astrophysics Data System (ADS)

    Zhang, Jingyong; Wu, Lingyun; Huang, Gang; Notaro, Michael

    2011-02-01

    In this study, we focus on a deciduous forest in central Massachusetts and investigate the relationships between global climate indices and CO2 exchange using eddy-covariance flux measurements from 1992 to 2007. Results suggest that large-scale circulation patterns influence the annual CO2 exchange in the forest through their effects on the local surface climate. Annual gross ecosystem exchange (GEE) in the forest is closely associated with spring El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), previous fall Atlantic Multidecadal Oscillation (AMO), and previous winter East Pacific-North Pacific (EP-NP) pattern. Annual net ecosystem exchange (NEE) responds to previous fall AMO and PDO, while annual respiration (R) is impacted by previous fall ENSO and Pacific/North American Oscillation (PNA). Regressions based on these relationships are developed to simulate the annual GEE, NEE, and R. To avoid problems of multicollinearity, we compute a "Composite Index for GEE (CIGEE)" based on a linear combination of spring ENSO and PDO, fall AMO, and winter EP-NP and a "Composite Index for R (CIR)" based on a linear combination of fall ENSO and PNA. CIGEE, CIR, and fall AMO and PDO can explain 41, 27, and 40% of the variance of the annual GEE, R, and NEE, respectively. We further apply the methodology to two other northern midlatitude forests and find that interannual variabilities in NEE of the two forests are largely controlled by large-scale circulation patterns. This study suggests that global climate indices provide the potential for predicting CO2 exchange variability in the northern midlatitude forests.

  16. The impact of large-scale circulation patterns on summer crop yields in IP

    NASA Astrophysics Data System (ADS)

    Capa Morocho, Mirian; Rodríguez Fonseca, Belén; Ruiz Ramos, Margarita

    2014-05-01

    Large-scale circulations patterns (ENSO, NAO) have been shown to have a significant impact on seasonal weather, and therefore on crop yield over many parts of the world(Garnett and Khandekar, 1992; Aasa et al., 2004; Rozas and Garcia-Gonzalez, 2012). In this study, we analyze the influence of large-scale circulation patterns and regional climate on the principal components of maize yield variability in Iberian Peninsula (IP) using reanalysis datasets. Additionally, we investigate the modulation of these relationships by multidecadal patterns. This study is performed analyzing long time series of maize yield, only climate dependent, computed with the crop model CERES-maize (Jones and Kiniry, 1986) included in Decision Support System for Agrotechnology Transfer (DSSAT v.4.5). To simulate yields, reanalysis daily data of radiation, maximum and minimum temperature and precipitation were used. The reanalysis climate data were obtained from National Center for Environmental Prediction (20th Century and NCEP) and European Centre for Medium-Range Weather Forecasts (ECMWF) data server (ERA 40 and ERA Interim). Simulations were run at five locations: Lugo (northwestern), Lerida (NE), Madrid (central), Albacete (southeastern) and Córdoba (S IP) (Gabaldón et al., 2013). From these time series standardized anomalies were calculated. Afterwards, time series were time filtered to focus on the interannual-to-multiannual variability, splitting up in two components: low frequency (LF) and high frequency (HF) time scales. The principal components of HF yield anomalies in IP were compared with a set of documented patterns. These relationships were compared with multidecadal patterns, as Atlanctic Multidecadal Oscillations (AMO) and Interdecadal Pacific Oscillations (IPO). The results of this study have important implications in crop forecasting. In this way, it may have a positive impact on both public (agricultural planning) and private (decision support to farmers, insurance

  17. Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

    PubMed Central

    Taguchi, Akiko; Ratnaraj, Jebadurai; Kabon, Barbara; Sharma, Neeru; Lenhardt, Rainer; Sessler, Daniel I.

    2005-01-01

    Background: Forced-air warming is sometimes unable to maintain perioperative normothermia. We therefore compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods: Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34°C. The volunteers were subsequently warmed for 2.5 hours with either a circulating-water garment or forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and “deep” arm and foot thermometers. Results: Heat production (≈ 60 kcal/h) and loss (≈45 kcal/h) were similar with each treatment before warming. The increase in heat transfer across anterior portions of the skin surface was similar with each warming system (≈65 kcal/h). Forced-air warming had no effect on posterior heat transfer whereas circulating-water transferred 21 ± 9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating-water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 ± 0.7°C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions: The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4°C/h faster than forced air. A substantial peripheral

  18. Two types of regional daily precipitation extremes over fujian-jiangxi of China and their related anomalous circulation patterns during boreal summer

    NASA Astrophysics Data System (ADS)

    Li, M.; Guan, Z.

    2015-12-01

    Based on daily rainfall data from CMA, best track data of Tropical Cyclones (TC) from JMA, and the NCEP-NCAR reanalysis from NOAA, regional mean daily precipitation extreme (RDPE) events over Fujian-Jiangxi Region (FJR) of China and the associated circulation anomalies have been investigated. During summers of 1979-2011, totaling 105 RDPE events are identified; out of which 35 are TC-influenced (TCIn-RDPE) and 70 no-TC-related (TCFr-RDPE). Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns, except they all occurred more frequently with stronger intensities in recent two decades other than in 1980s. TCFr-RDPEs usually occur in June while TCIn-RDPEs mainly do in July-August. When TCFr-RDPEs happen, a center of the departure cyclonic circulation is observed over FJR, with an anomalous anticyclonic circulation to the south of this region. The warm/moist airflows from the South-China-Sea (SCS) and western Pacific meet with colder air from the north to form a narrow convergent belt of water vapor over FJR. Simultaneously, positive diabatic forcing anomalies are observed over FJR whereas negatives over both its south and north sides, facilitating the formation and maintenance of the cyclonic circulation anomaly as well as the upward motion of the atmosphere over FJR. As TCIn-RDPEs occur, southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation. An anomalous anticyclonic circulation in mid- and high-latitudes north of the FJR exist in mid and lower troposphere, which looks opposite as compared to that of TCFr-RDPE events. The abundant warm/wet air is carried into the FJR from both the Indian Ocean and SCS, leading to large amount of latent heat to release over FJR, inducing strong ascent of air there. Furthermore, large differences are also found in ways of Rossby wave energy propagation between these two type RDPE events. These results are helpful for us to

  19. Reproducible copy number variation patterns among single circulating tumor cells of lung cancer patients.

    PubMed

    Ni, Xiaohui; Zhuo, Minglei; Su, Zhe; Duan, Jianchun; Gao, Yan; Wang, Zhijie; Zong, Chenghang; Bai, Hua; Chapman, Alec R; Zhao, Jun; Xu, Liya; An, Tongtong; Ma, Qi; Wang, Yuyan; Wu, Meina; Sun, Yu; Wang, Shuhang; Li, Zhenxiang; Yang, Xiaodan; Yong, Jun; Su, Xiao-Dong; Lu, Youyong; Bai, Fan; Xie, X Sunney; Wang, Jie

    2013-12-24

    Circulating tumor cells (CTCs) enter peripheral blood from primary tumors and seed metastases. The genome sequencing of CTCs could offer noninvasive prognosis or even diagnosis, but has been hampered by low single-cell genome coverage of scarce CTCs. Here, we report the use of the recently developed multiple annealing and looping-based amplification cycles for whole-genome amplification of single CTCs from lung cancer patients. We observed characteristic cancer-associated single-nucleotide variations and insertions/deletions in exomes of CTCs. These mutations provided information needed for individualized therapy, such as drug resistance and phenotypic transition, but were heterogeneous from cell to cell. In contrast, every CTC from an individual patient, regardless of the cancer subtypes, exhibited reproducible copy number variation (CNV) patterns, similar to those of the metastatic tumor of the same patient. Interestingly, different patients with the same lung cancer adenocarcinoma (ADC) shared similar CNV patterns in their CTCs. Even more interestingly, patients of small-cell lung cancer have CNV patterns distinctly different from those of ADC patients. Our finding suggests that CNVs at certain genomic loci are selected for the metastasis of cancer. The reproducibility of cancer-specific CNVs offers potential for CTC-based cancer diagnostics.

  20. Reproducible copy number variation patterns among single circulating tumor cells of lung cancer patients

    PubMed Central

    Ni, Xiaohui; Zhuo, Minglei; Su, Zhe; Duan, Jianchun; Gao, Yan; Wang, Zhijie; Zong, Chenghang; Bai, Hua; Chapman, Alec R.; Zhao, Jun; Xu, Liya; An, Tongtong; Ma, Qi; Wang, Yuyan; Wu, Meina; Sun, Yu; Wang, Shuhang; Li, Zhenxiang; Yang, Xiaodan; Yong, Jun; Su, Xiao-Dong; Lu, Youyong; Bai, Fan; Xie, X. Sunney; Wang, Jie

    2013-01-01

    Circulating tumor cells (CTCs) enter peripheral blood from primary tumors and seed metastases. The genome sequencing of CTCs could offer noninvasive prognosis or even diagnosis, but has been hampered by low single-cell genome coverage of scarce CTCs. Here, we report the use of the recently developed multiple annealing and looping-based amplification cycles for whole-genome amplification of single CTCs from lung cancer patients. We observed characteristic cancer-associated single-nucleotide variations and insertions/deletions in exomes of CTCs. These mutations provided information needed for individualized therapy, such as drug resistance and phenotypic transition, but were heterogeneous from cell to cell. In contrast, every CTC from an individual patient, regardless of the cancer subtypes, exhibited reproducible copy number variation (CNV) patterns, similar to those of the metastatic tumor of the same patient. Interestingly, different patients with the same lung cancer adenocarcinoma (ADC) shared similar CNV patterns in their CTCs. Even more interestingly, patients of small-cell lung cancer have CNV patterns distinctly different from those of ADC patients. Our finding suggests that CNVs at certain genomic loci are selected for the metastasis of cancer. The reproducibility of cancer-specific CNVs offers potential for CTC-based cancer diagnostics. PMID:24324171

  1. Landscape analysis and pattern of hurricane impact and circulation on mangrove forests of the everglades

    USGS Publications Warehouse

    Doyle, T.W.; Krauss, K.W.; Wells, C.J.

    2009-01-01

    The Everglades ecosystem contains the largest contiguous tract of mangrove forest outside the tropics that were also coincidentally intersected by a major Category 5 hurricane. Airborne videography was flown to capture the landscape pattern and process of forest damage in relation to storm trajectory and circulation. Two aerial video transects, representing different topographic positions, were used to quantify forest damage from video frame analysis in relation to prevailing wind force, treefall direction, and forest height. A hurricane simulation model was applied to reconstruct wind fields corresponding to the ground location of each video frame and to correlate observed treefall and destruction patterns with wind speed and direction. Mangrove forests within the storm's eyepath and in the right-side (forewind) quadrants suffered whole or partial blowdowns, while left-side (backwind) sites south of the eyewall zone incurred moderate canopy reduction and defoliation. Sites along the coastal transect sustained substantially more storm damage than sites along the inland transect which may be attributed to differences in stand exposure and/or stature. Observed treefall directions were shown to be non-random and associated with hurricane trajectory and simulated forewind azimuths. Wide-area sampling using airborne videography provided an efficient adjunct to limited ground observations and improved our spatial understanding of how hurricanes imprint landscape-scale patterns of disturbance. ?? 2009 The Society of Wetland Scientists.

  2. Can tree-ring proxy reflect summer temperature extremes and their associated circulation patterns over Fennoscandia?

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Tree-ring maximum latewood density (MXD) records in Fennoscandia have been widely used to infer the regional and hemispheric-scale mean temperature variability. Here, we explore whether the tree-ring record can be used to infer the variability of summer temperature extremes over Fennoscandia through a statistical analyses of gridded instrumental reanalysis and tree-ring data. The first principal component (PC1) of the MXD network in Fennoscandia, which explains 50% variance of the summer warm-day extreme variability over the period 1901-1978, has a mopolar structure with the highest loadings in the central and northern part of Fennoscandia. The corresponding time series (PC1) is influenced by the variability of a blocking-like anticyclonic pattern over Fennoscandia, and the northward shift of northeast Atlantic high-altitude jet stream. The strongest correlations are found between the PC1 and the summer warm-day extremes over Fennoscandia, consistent with the anticyclonic pattern. This study shows that the Fennoscandian MXD network can be used to infer the variability of the past high-temperature extremes in Fennoscandia and their associated circulation patterns over summer.

  3. Non-random fragmentation patterns in circulating cell-free DNA reflect epigenetic regulation

    PubMed Central

    2015-01-01

    Background The assessment of cell-free circulating DNA fragments, also known as a "liquid biopsy" of the patient's plasma, is an important source for the discovery and subsequent non-invasive monitoring of cancer and other pathological conditions. Although the nucleosome-guided fragmentation patterns of cell-free DNA (cfDNA) have not yet been studied in detail, non-random representation of cfDNA sequencies may reflect chromatin features in the tissue of origin at gene-regulation level. Results In this study, we investigated the association between epigenetic landscapes of human tissues evident in the patterns of cfDNA in plasma by deep sequencing of human cfDNA samples. We have demonstrated that baseline characteristics of cfDNA fragmentation pattern are in concordance with the ones corresponding to cell lines-derived. To identify the loci differentially represented in cfDNA fragment, we mapped the transcription start sites within the sequenced cfDNA fragments and tested for association of these genomic coordinates with the relative strength and the patterns of gene expressions. Preselected sets of house-keeping and tissue specific genes were used as models for actively expressed and silenced genes. Developed measure of gene regulation was able to differentiate these two sets based on sequencing coverage near gene transcription start site. Conclusion Experimental outcomes suggest that cfDNA retains characteristics previously noted in genome-wide analysis of chromatin structure, in particular, in MNase-seq assays. Thus far the analysis of the DNA fragmentation pattern may aid further developing of cfDNA based biomarkers for a variety of human conditions. PMID:26693644

  4. Surface circulation patterns in the Gulf of California derived from MODIS Aqua 250 m

    NASA Astrophysics Data System (ADS)

    Martínez-Flores, G.; Salinas-González, F.; Gutiérrez de Velasco-Sanromán, G.; Godínez-Orta, L.

    2009-04-01

    The Gulf of California (GC) is a marginal elongated and semi-enclosed sea located at northwest of Mexico, between the Peninsula of Baja California and the mainland Mexico. The considered area average 150 km in width and 1500 km in length, from the mouth of the Colorado River to Cabo Corrientes, Jalisco. It has a maximum depth of 3600 m at the southern inlet and the northern region average 200 m in deep. The study of superficial circulation patterns in the GC is of interest because its relevance to the mechanisms of transport for distribution of a variety of materials -plankton, contaminants, microalgae, etc.- and its association with areas of sedimentary deposits, zones where there is a higher probability for fishing or related to the presence of certain species of marine life. Recent studies explain the circulation of the GC as a result of the Pacific Ocean's forcing, wind, heat fluxes on the sea surface and the interaction between the flow produced by these agents and bathymetry. The objective of this work was to obtain evidence of the patterns of surface circulation using a spatial resolution of 250 m over a period of two to seven days (depending on cloud cover), which offered images from the MODIS Level 1B. This essay is an attempt to contribute with more information to the understanding of the regional dynamics of the GC and its local influence on the zones bordering the coast. Thus, MODIS Aqua 250 m data was used, to which algorithms were applied in order to enhance the contrast of reflectance levels of these bands (0.620-0.670 and 0.841-0.876 µm) within the marine environment. The results are associated with suspended particulate matter (SPM), which we used as tracers of the surface circulation, using a sequence of images from January 2004 to December 2008. Algorithms for dust and cloud detection were used and incorporated with thermal band images, in which zones of terrigenous contribution by eolian transport were identified. Furthermore, pluvial

  5. Circulation patterns and wave climate along the coast of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Rasilla Álvarez, D.; García Codrán, J. C.

    2010-09-01

    Evidences of an active erosion (beach retreat, falling cliffs, damaged infrastructures) are observed in many coastal areas around the Iberian Peninsula. Morphogenetic coastal processes result from individual episodes of storminess that can accelerate or mitigate the expected impacts of the global rising trend of average sea levels. Thus, a good understanding of the local forcing processes is required in order to assess the impacts of future sea levels. The spatial and temporal variability of the wave climate along the cost of the Iberian Peninsula and their relationships with regional scale circulation patterns and local-scale winds are the main objectives of this contribution. The oceanographic data set consists of observed hourly data from 7 buoys disseminated along the Spanish coastline, and hindcasted 3-hourly analogous parameters (SIMAR 44 database), provided by Puertos del Estado. Sea level pressure, surface 10m U and V wind components gridded data were obtained from NCEP Reanalysis, while storm tracks and cyclone statistics were extracted from the CDC Map Room Climate Products Storm Track Data (http://www.cdc.noaa.gov/map/clim/st_data.html). The influence of the local conditions was highlighted comparing meteorological data from the buoys and synop reports from coastal stations. To explore the regional atmospheric mechanisms responsible for the wave variability, a regional Eulerian approach (a synoptic typing) were combined with a larger-scale Lagrangian method, based on the analysis of storm-tracks over the area. The synoptic catalogue was obtained following a well-known procedure that combines Principal Component Analysis (PCA) for reduction purposes and clustering (Ward plus K-means) to define the circulation types. As expected, rougher wave climate are observed along the northern and western coast of the Iberian Peninsula, open to the Atlantic storms. The Mediterranean shorelines experiences calmer conditions, although the Gulf of Lions, Catalonian coast

  6. Unusual Circulation Patterns of the Rias Baixas Induced by Minho Freshwater Intrusion (NW of the Iberian Peninsula)

    PubMed Central

    Sousa, Magda Catarina; Mendes, Renato; Alvarez, Ines; Vaz, Nuno; Gomez-Gesteira, Moncho; Dias, João Miguel

    2014-01-01

    The Minho River, situated 30 km south of the Rias Baixas, is the most important freshwater source flowing into the Western Galician coast (NW of the Iberian Peninsula). The buoyancy generated by the Minho estuarine plume can reverse the normal circulation pattern inside the Rias Baixas affecting the exchange between the Rias and the ocean, changing the input of nutrients. Nevertheless, this inversion of the circulation patterns is not a well-monitored phenomenon. The only published results based on in situ data related to the presence of the Minho River plume inside the Rias de Vigo and Pontevedra correspond to an event measured on spring 1998. In this case unexpectedly higher inflow surface current velocities were found at the Ria de Pontevedra, located further away from Minho River. Thus, the main aim of this study is to research the main factors inducing this unusual pattern on the circulation of the Rias de Vigo and Pontevedra. A numerical model implementation of MOHID previously developed, calibrated, and validated for this coastal area was used. Several scenarios were performed in order to explain the individual effect of the Minho River, rivers discharging into each Rias, and estuarine morphology changes. According to the model results, the Minho River discharge is a key factor in the establishment of the negative circulation, while small rivers inside the Rias slightly attenuate this circulation. The negative circulation was stronger in Ria de Pontevedra independently of the distance of this coastal system from the Minho River mouth, showing that morphologic estuarine features are the main factor justifying the different local circulation patterns. PMID:25402444

  7. Plant wax δD values record changing Eastern Mediterranean atmospheric circulation patterns during the 8.2 kyr B.P. climatic event

    NASA Astrophysics Data System (ADS)

    Schemmel, Fabian; Niedermeyer, Eva M.; Schwab, Valérie F.; Gleixner, Gerd; Pross, Jörg; Mulch, Andreas

    2016-02-01

    Throughout the Holocene, the climate of the Mediterranean region has been strongly influenced by variability in the atmospheric circulation of the high and low latitudes. A prominent example for such Holocene climate perturbations is the '8.2 kyr B.P. climatic event'. Reorganization of Northern Hemisphere atmospheric circulation patterns resulted in variations of temperature and precipitation distribution across the Mediterranean. The effects of changing high- and low-latitude atmospheric circulation on Mediterranean climate in relation to the 8.2 kyr B.P. climatic event are, however, not well understood. Here we present a high-resolution record of stable hydrogen isotope composition of plant-wax n-alkanes (δDwax) across the 8.2 kyr B.P. climatic event from the Tenaghi Philippon peat deposit (NE Greece) in order to characterize patterns of precipitation and changes in atmospheric circulation in the Eastern Mediterranean region. Our record reveals pronounced changes in δDwax that correlate closely with previously published palynological data. A long-term decline in δDwax values characterizes the lower part of the section. The 8.2 kyr B.P. climatic event itself is connected to two distinct positive δDwax excursions: a minor shift in δDwax around 8.2 kyr B.P. and a major shift in δDwax between ca. 8.1 and 8.0 kyr B.P.. The upper part of the section shows a progressive trend towards higher δDwax values. We link shifts in δDwax to changes in Mediterranean air mass trajectories supplying precipitation to NE Greece caused by variations in the relative contributions of northerly-derived, D-depleted moisture and southerly-derived, D-enriched moisture. Possible control mechanisms for alternating air mass trajectories include changes in the influence of the Siberian High and differences in the influence of the African and Asian monsoon circulation on anticyclonic conditions in the Mediterranean region as well as regional inflow of moist air masses from the Aegean Sea.

  8. Decadal slowdown in global air temperature rise triggered by variability in the Atlantic Meridional Overturning Circulation

    NASA Astrophysics Data System (ADS)

    England, Matthew H.

    2015-04-01

    Various explanations have been proposed for the recent slowdown in global surface air temperature (SAT) rise, either involving enhanced ocean heat uptake or reduced radiation reaching Earth's surface. Among the mechanisms postulated involving enhanced ocean heat uptake, past work has argued for both a Pacific and Atlantic origin, with additional contributions from the Southern Ocean. Here we examine the mechanisms driving 'hiatus' periods originating out of the Atlantic Ocean. We show that while Atlantic-driven hiatuses are entirely plausible and consistent with known climate feedbacks associated with variability in the Atlantic Meridional Overturning Circulation (AMOC), the present climate state is configured to enhance global-average SAT, not reduce it. We show that Atlantic hiatuses are instead characterised by anomalously cool fresh oceanic conditions in the North Atlantic, with the atmosphere advecting the cool temperature signature zonally. Compared to the 1980s and 1990s, however, the mean climate since 2001 has been characterised by a warm saline North Atlantic, suggesting the AMOC cannot be implicated as a direct driver of the current hiatus. We further discuss the impacts of a warm tropical Atlantic on the unprecedented trade wind acceleration in the Pacific Ocean, and propose that this is the main way that the Atlantic has contributed to the present "false pause" in global warming.

  9. Identification of tissue-specific cell death using methylation patterns of circulating DNA.

    PubMed

    Lehmann-Werman, Roni; Neiman, Daniel; Zemmour, Hai; Moss, Joshua; Magenheim, Judith; Vaknin-Dembinsky, Adi; Rubertsson, Sten; Nellgård, Bengt; Blennow, Kaj; Zetterberg, Henrik; Spalding, Kirsty; Haller, Michael J; Wasserfall, Clive H; Schatz, Desmond A; Greenbaum, Carla J; Dorrell, Craig; Grompe, Markus; Zick, Aviad; Hubert, Ayala; Maoz, Myriam; Fendrich, Volker; Bartsch, Detlef K; Golan, Talia; Ben Sasson, Shmuel A; Zamir, Gideon; Razin, Aharon; Cedar, Howard; Shapiro, A M James; Glaser, Benjamin; Shemer, Ruth; Dor, Yuval

    2016-03-29

    Minimally invasive detection of cell death could prove an invaluable resource in many physiologic and pathologic situations. Cell-free circulating DNA (cfDNA) released from dying cells is emerging as a diagnostic tool for monitoring cancer dynamics and graft failure. However, existing methods rely on differences in DNA sequences in source tissues, so that cell death cannot be identified in tissues with a normal genome. We developed a method of detecting tissue-specific cell death in humans based on tissue-specific methylation patterns in cfDNA. We interrogated tissue-specific methylome databases to identify cell type-specific DNA methylation signatures and developed a method to detect these signatures in mixed DNA samples. We isolated cfDNA from plasma or serum of donors, treated the cfDNA with bisulfite, PCR-amplified the cfDNA, and sequenced it to quantify cfDNA carrying the methylation markers of the cell type of interest. Pancreatic β-cell DNA was identified in the circulation of patients with recently diagnosed type-1 diabetes and islet-graft recipients; oligodendrocyte DNA was identified in patients with relapsing multiple sclerosis; neuronal/glial DNA was identified in patients after traumatic brain injury or cardiac arrest; and exocrine pancreas DNA was identified in patients with pancreatic cancer or pancreatitis. This proof-of-concept study demonstrates that the tissue origins of cfDNA and thus the rate of death of specific cell types can be determined in humans. The approach can be adapted to identify cfDNA derived from any cell type in the body, offering a minimally invasive window for diagnosing and monitoring a broad spectrum of human pathologies as well as providing a better understanding of normal tissue dynamics. PMID:26976580

  10. Identification of tissue-specific cell death using methylation patterns of circulating DNA

    PubMed Central

    Lehmann-Werman, Roni; Neiman, Daniel; Zemmour, Hai; Moss, Joshua; Magenheim, Judith; Vaknin-Dembinsky, Adi; Rubertsson, Sten; Nellgård, Bengt; Blennow, Kaj; Zetterberg, Henrik; Spalding, Kirsty; Haller, Michael J.; Wasserfall, Clive H.; Schatz, Desmond A.; Greenbaum, Carla J.; Dorrell, Craig; Grompe, Markus; Zick, Aviad; Hubert, Ayala; Maoz, Myriam; Fendrich, Volker; Bartsch, Detlef K.; Golan, Talia; Ben Sasson, Shmuel A.; Zamir, Gideon; Razin, Aharon; Cedar, Howard; Shapiro, A. M. James; Glaser, Benjamin; Shemer, Ruth; Dor, Yuval

    2016-01-01

    Minimally invasive detection of cell death could prove an invaluable resource in many physiologic and pathologic situations. Cell-free circulating DNA (cfDNA) released from dying cells is emerging as a diagnostic tool for monitoring cancer dynamics and graft failure. However, existing methods rely on differences in DNA sequences in source tissues, so that cell death cannot be identified in tissues with a normal genome. We developed a method of detecting tissue-specific cell death in humans based on tissue-specific methylation patterns in cfDNA. We interrogated tissue-specific methylome databases to identify cell type-specific DNA methylation signatures and developed a method to detect these signatures in mixed DNA samples. We isolated cfDNA from plasma or serum of donors, treated the cfDNA with bisulfite, PCR-amplified the cfDNA, and sequenced it to quantify cfDNA carrying the methylation markers of the cell type of interest. Pancreatic β-cell DNA was identified in the circulation of patients with recently diagnosed type-1 diabetes and islet-graft recipients; oligodendrocyte DNA was identified in patients with relapsing multiple sclerosis; neuronal/glial DNA was identified in patients after traumatic brain injury or cardiac arrest; and exocrine pancreas DNA was identified in patients with pancreatic cancer or pancreatitis. This proof-of-concept study demonstrates that the tissue origins of cfDNA and thus the rate of death of specific cell types can be determined in humans. The approach can be adapted to identify cfDNA derived from any cell type in the body, offering a minimally invasive window for diagnosing and monitoring a broad spectrum of human pathologies as well as providing a better understanding of normal tissue dynamics. PMID:26976580

  11. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS).

    PubMed

    Nyamweya, Chrispine; Desjardins, Christopher; Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September-May) and mixing (June-August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore-offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria. PMID:27030983

  12. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS)

    PubMed Central

    Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September–May) and mixing (June–August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore—offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria. PMID:27030983

  13. Identification of tissue-specific cell death using methylation patterns of circulating DNA.

    PubMed

    Lehmann-Werman, Roni; Neiman, Daniel; Zemmour, Hai; Moss, Joshua; Magenheim, Judith; Vaknin-Dembinsky, Adi; Rubertsson, Sten; Nellgård, Bengt; Blennow, Kaj; Zetterberg, Henrik; Spalding, Kirsty; Haller, Michael J; Wasserfall, Clive H; Schatz, Desmond A; Greenbaum, Carla J; Dorrell, Craig; Grompe, Markus; Zick, Aviad; Hubert, Ayala; Maoz, Myriam; Fendrich, Volker; Bartsch, Detlef K; Golan, Talia; Ben Sasson, Shmuel A; Zamir, Gideon; Razin, Aharon; Cedar, Howard; Shapiro, A M James; Glaser, Benjamin; Shemer, Ruth; Dor, Yuval

    2016-03-29

    Minimally invasive detection of cell death could prove an invaluable resource in many physiologic and pathologic situations. Cell-free circulating DNA (cfDNA) released from dying cells is emerging as a diagnostic tool for monitoring cancer dynamics and graft failure. However, existing methods rely on differences in DNA sequences in source tissues, so that cell death cannot be identified in tissues with a normal genome. We developed a method of detecting tissue-specific cell death in humans based on tissue-specific methylation patterns in cfDNA. We interrogated tissue-specific methylome databases to identify cell type-specific DNA methylation signatures and developed a method to detect these signatures in mixed DNA samples. We isolated cfDNA from plasma or serum of donors, treated the cfDNA with bisulfite, PCR-amplified the cfDNA, and sequenced it to quantify cfDNA carrying the methylation markers of the cell type of interest. Pancreatic β-cell DNA was identified in the circulation of patients with recently diagnosed type-1 diabetes and islet-graft recipients; oligodendrocyte DNA was identified in patients with relapsing multiple sclerosis; neuronal/glial DNA was identified in patients after traumatic brain injury or cardiac arrest; and exocrine pancreas DNA was identified in patients with pancreatic cancer or pancreatitis. This proof-of-concept study demonstrates that the tissue origins of cfDNA and thus the rate of death of specific cell types can be determined in humans. The approach can be adapted to identify cfDNA derived from any cell type in the body, offering a minimally invasive window for diagnosing and monitoring a broad spectrum of human pathologies as well as providing a better understanding of normal tissue dynamics.

  14. Simulation of Lake Victoria Circulation Patterns Using the Regional Ocean Modeling System (ROMS).

    PubMed

    Nyamweya, Chrispine; Desjardins, Christopher; Sigurdsson, Sven; Tomasson, Tumi; Taabu-Munyaho, Anthony; Sitoki, Lewis; Stefansson, Gunnar

    2016-01-01

    Lake Victoria provides important ecosystem services including transport, water for domestic and industrial uses and fisheries to about 33 million inhabitants in three East African countries. The lake plays an important role in modulating regional climate. Its thermodynamics and hydrodynamics are also influenced by prevailing climatic and weather conditions on diel, seasonal and annual scales. However, information on water temperature and circulation in the lake is limited in space and time. We use a Regional Oceanographic Model System (ROMS) to simulate these processes from 1st January 2000 to 31st December 2014. The model is based on real bathymetry, river runoff and atmospheric forcing data using the bulk flux algorithm. Simulations show that the water column exhibits annual cycles of thermo-stratification (September-May) and mixing (June-August). Surface water currents take different patterns ranging from a lake-wide northward flow to gyres that vary in size and number. An under flow exists that leads to the formation of upwelling and downwelling regions. Current velocities are highest at the center of the lake and on the western inshore waters indicating enhanced water circulation in those areas. However, there is little exchange of water between the major gulfs (especially Nyanza) and the open lake, a factor that could be responsible for the different water quality reported in those regions. Findings of the present study enhance understanding of the physical processes (temperature and currents) that have an effect on diel, seasonal, and annual variations in stratification, vertical mixing, inshore-offshore exchanges and fluxes of nutrients that ultimately influence the biotic distribution and trophic structure. For instance information on areas/timing of upwelling and vertical mixing obtained from this study will help predict locations/seasons of high primary production and ultimately fisheries productivity in Lake Victoria.

  15. Seasonal pattern of the acute mortality effects of air pollution.

    PubMed

    Qian, Zhengmin; Lin, Hung-Mo; Stewart, Walter F; Kong, Linli; Xu, Fen; Zhou, Denjin; Zhu, Zhicao; Liang, Shengwen; Chen, Weiqing; Shah, Nirav; Stetter, Christy; He, Qingci

    2010-04-01

    Evidence of seasonal variation of acute mortality effects of air pollution is inconsistent. The seasonal patterns of associations between daily mortality and daily mean concentrations of particulate matter 10 microm or less in aerodynamic diameter (PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2) were examined using 4 yr of data (2001-2004) in Wuhan, China. Four distinct seasons occur in Wuhan, where approximately 4.5 million residents live in the city core area of 201 km2. Air pollution levels are higher and pollution ranges are wider in Wuhan than in most cities. Quasi-likelihood estimation within the context of the generalized additive models (natural spline [NS] models in R) was used to model the natural logarithm of the expected daily death counts as a function of the predictor variables. The estimates of the interaction between seasons and pollution were obtained from the main effects and pollutant season interaction models. It was found that the interactions between three pollutants and cause-specific mortality were statistically significant (P < 0.05). The strongest effects occurred consistently in winter for all-natural, cardiovascular, stroke, and respiratory mortality. Every 10-microg/m3 increase in PM10 daily concentration at lag 0-1 days was associated with an increase in all-natural mortality of 0.69% (95% confidence interval [CI]: 0.44-0.94%) for winter, 0.34% (95% CI: 0.00-0.69%) for spring, 0.45% (95% CI: -0.13 to 1.04%) for summer, and -0.21% (95% CI: -0.54 to 0.12%) for fall. The results show a clear seasonal pattern of acute mortality effects of ambient air pollution and the strongest effects occurred during winter in the study city.

  16. Surface circulation patterns at the southeastern Bay of Biscay: new observations from HF radar data

    NASA Astrophysics Data System (ADS)

    Solabarrieta, L.; Rubio, A.; Medina, R.; Paduan, J. D.; Castanedo, S.; Fontán, A.; Cook, M.; González, M.

    2012-12-01

    A CODAR Seasonde High Frequency (HF) radar network has been operational since the beginning of 2009 for the oceanic region of the Basque Country, Spain (south-eastern Bay of Biscay, Atlantic Ocean). It forms part of the Basque operational data acquisition system, established by the Directorate of Emergency Attention and Meteorology of the Basque Government. It is made up of two antennas, at the capes Higer (43d 23.554' N, 1d 47.745' W) and Matxitxako (43d 7.350' N, 2d 45.163' W), emitting at 4.525 MHz frequency and 30 kHz bandwidth. This system provides hourly surface currents with 5.12 km spatial resolution, covering 10,000 km2. Space- and time-covering measurements have been available in the study area since 2009. The data contribute considerably to the study of surface current patterns and the main physical processes in the area. Additional applications relate to security of navigation, maritime rescue, validation and improvement of numerical models, etc. For comparison with other validation studies and to obtain an estimate of the performance of the Basque system, statistical and spectral analysis of the surface currents obtained through the HF radar and different in-situ platforms have been conducted. The analyses show values of comparison between the different measuring systems consistent with those done by other authors (Paduan and Rosenfeld, 1996; Kaplan et al., 2005). The radar is able to reproduce the time evolution of the currents with a reasonable accuracy; likewise, the main three spectral peaks (inertial, semidiurnal and diurnal) are well resolved. In this context, the aim of this work is to show the HF radar ability to measure accurately the surface currents in the south-eastern Bay of Biscay and to study the ocean circulation in the area (figures 1 and 2). Surface current patterns are analysed and described for the period 2009-2011, for different timescales. A clear seasonality at a large-scale has been observed in accordance with previous work

  17. Characteristics of atmospheric circulation patterns associated with extreme temperatures over North America in observations and climate models

    NASA Astrophysics Data System (ADS)

    Loikith, Paul C.

    Motivated by a desire to understand the physical mechanisms involved in future anthropogenic changes in extreme temperature events, the key atmospheric circulation patterns associated with extreme daily temperatures over North America in the current climate are identified. Several novel metrics are used to systematically identify and describe these patterns for the entire continent. The orientation, physical characteristics, and spatial scale of these circulation patterns vary based on latitude, season, and proximity to important geographic features (i.e., mountains, coastlines). The anomaly patterns associated with extreme cold events tend to be similar to, but opposite in sign of, those associated with extreme warm events, especially within the westerlies, and tend to scale with temperature in the same locations. The influence of the Pacific North American (PNA) pattern, the Northern Annular Mode (NAM), and the El Niño-Southern Oscillation (ENSO) on extreme temperature days and months shows that associations between extreme temperatures and the PNA and NAM are stronger than associations with ENSO. In general, the association with extremes tends to be stronger on monthly than daily time scales. Extreme temperatures are associated with the PNA and NAM in locations typically influenced by these circulation patterns; however many extremes still occur on days when the amplitude and polarity of these patterns do not favor their occurrence. In winter, synoptic-scale, transient weather disturbances are important drivers of extreme temperature days; however these smaller-scale events are often concurrent with amplified PNA or NAM patterns. Associations are weaker in summer when other physical mechanisms affecting the surface energy balance, such as anomalous soil moisture content, are associated with extreme temperatures. Analysis of historical runs from seventeen climate models from the CMIP5 database suggests that most models simulate realistic circulation patterns

  18. Trend analysis of air temperature time series in Greece and their relationship with circulation using surface and satellite data: recent trends and an update to 2013

    NASA Astrophysics Data System (ADS)

    Feidas, H.

    2016-07-01

    In this paper, the surface and lower tropospheric temperature trends in Greece and their relationship to the atmospheric circulation for the period 1955-2013 were examined, updating the study of Feidas et al. (Theor Appl Climatol 79:185-208, 2004) for data observed during the 12-year period 2002-2013. The trend analysis is based on a combination of three statistical tests. The trends are now examined for all the seasonal time series, new atmospheric circulation indices were added in the analysis, and maps with the spatial distribution of correlation between air temperature and atmospheric circulation were constructed and analysed. The series updated to 2013 for 18 stations reveal a clearer positive trend than that found for the period 1955-2001 on both the annual and the seasonal timescales. The warming signal detected only in summer in the study of Feidas et al. (Theor Appl Climatol 79:185-208, 2004) has now intensified and spread in other seasons. This warming appears to be mainly caused by the very high temperatures in the last decade (after 2004) of the record. At the national scale, there is now a match between surface temperature trends in Greece and Northern Hemisphere (NH) but only for summer, spring and annual time series, which are the only time series presenting a statistically significant warming trend in Greece. Satellite-induced lower tropospheric temperatures now show a statistically significant tropospheric temperature warming trend for the period 1979-2013, for both areas (Greece and NH). Lower tropospheric and surface air temperatures for the same period (1979-2013) show a very good agreement, with differences only in winter and summer for Greece. The influence of atmospheric circulation on the temperature variability in Greece was also examined using two more circulation indices: the Eastern Mediterranean Pattern Index (EMPI) and the North-Sea Caspian Pattern Index (NCPI). EMPI and especially NCPI explain better now the temperature variance in

  19. Windflow circulation patterns in a coastal dune blowout, south coast of Lake Michigan

    USGS Publications Warehouse

    Fraser, G.S.; Bennett, S.W.; Olyphant, G.A.; Bauch, N.J.; Ferguson, V.; Gellasch, C.A.; Millard, C.L.; Mueller, B.; O'Malley, P. J.; Way, J.N.; Woodfield, M.C.

    1998-01-01

    The windflow patterns in a large active blowout in a coastal dune on the southern shore of Lake Michigan were intensively monitored during a two-day period when the predominant winds shifted from onshore (Day 1) to offshore (Day 2). The wind data were used in conjunction with mapped geomorphic features and sedimentologic characteristics to infer the following aspects of blowout evolution: (1) Prevailing winds are transformed considerably once they enter the blowout. Flow separation occurs when offshore winds enter the blowout over the steep back wall. Separated flows may, in turn, induce countercurrent flows within the trough. Flow expansion and deceleration occur when onshore winds enter over gently sloping walls at the front of the blowout. (2) Maximum erosion occurs along the deflationary floor near the entrance to the blowout, and lateral extensional lobes are also expanding the blowout to the east. Sand avalanches down the eastern and western lateral walls toward the deflationary floor where it is moved toward the rear of the blowout and up the ramp at the south end. Sand leaves the blowout as a series of depositional lobes prograding out onto the surface of the host dune along the south and east walls. (3) Vegetation prevents expansion of the blowout in certain directions and impediments to flow, such as slump blocks, alter circulation patterns and sand transport paths. (4) Prevailing onshore winds deflate the floor and promote eastward expansion of lateral erosional lobes, whereas strong flows from the southwest apparently are the main cause of transport up the transportational ramp and over the south wall of the blowout.

  20. Determination of circulation and turbidity patterns in Kerr Lake from LANDSAT MSS imagery. [Kerr Lake, Virginia, North Carolina

    NASA Technical Reports Server (NTRS)

    Lecroy, S. R. (Principal Investigator)

    1981-01-01

    The LANDSAT imagery was historically analyzed to determine the circulation and turbidity patterns of Kerr Lake, located on the Virginia-North Carolina border. By examining the seasonal and regional turbidity and circulation patterns, a record of sediment transport and possible disposition can be obtained. Sketches were generated, displaying different intensities of brightness observed in bands 5 and 7 of LANDSAT's multispectral scanner data. Differences in and between bands 5 and 7 indicate variances in the levels of surface sediment concentrations. High sediment loads are revealed when distinct patterns appear in the band 7 imagery. The upwelled signal is exponential in nature and saturates in band 5 at low wavelengths for large concentrations of suspended solids.

  1. Air pollution exposure: An activity pattern approach for active transportation

    NASA Astrophysics Data System (ADS)

    Adams, Matthew D.; Yiannakoulias, Nikolaos; Kanaroglou, Pavlos S.

    2016-09-01

    In this paper, we demonstrate the calculation of personal air pollution exposure during trips made by active transportation using activity patterns without personal monitors. We calculate exposure as the inhaled dose of particulate matter 2.5 μg or smaller. Two modes of active transportation are compared, and they include cycling and walking. Ambient conditions are calculated by combining mobile and stationary monitoring data in an artificial neural network space-time model. The model uses a land use regression framework and has a prediction accuracy of R2 = 0.78. Exposure is calculated at 10 m or shorter intervals during the trips using inhalation rates associated with both modes. The trips are children's routes between home and school. The average dose during morning cycling trips was 2.17 μg, during morning walking trips was 3.19 μg, during afternoon cycling trips was 2.19 μg and during afternoon walking trips was 3.23 μg. The cycling trip dose was significantly lower than the walking trip dose. The air pollution exposure during walking or cycling trips could not be strongly predicted by either the school or household ambient conditions, either individually or in combination. Multiple linear regression models regressing both the household and school ambient conditions against the dose were only able to account for, at most, six percent of the variance in the exposure. This paper demonstrates that incorporating activity patterns when calculating exposure can improve the estimate of exposure compared to its calculation from ambient conditions.

  2. Seasonal circulation patterns of the Yellow and East China Seas derived from satellite-tracked drifter trajectories and hydrographic observations

    NASA Astrophysics Data System (ADS)

    Lie, Heung-Jae; Cho, Cheol-Ho

    2016-08-01

    We investigated seasonal circulation patterns of the Yellow and East China Seas (YECS), by reviewing previous works on the circulation and its dominant currents, and taking into account newly-compiled trajectories of satellite-tracked drifters collected between the 1980s and 2000s. The circulation patterns suggested before the 1990s can be categorized into two groups, depending on the identified origin of the Tsushima Warm Current in the Korea-Tsushima Straits: (i) branching from the Kuroshio southwest of Kyushu, or (ii) northeastward continuation of the Taiwan Strait throughflow. The branching of the Kuroshio southwest of Kyushu and northeast of Taiwan was clearly evidenced by current measurements and concurrent hydrographic surveys. However, there is still no clear evidence for the northeastward pathway of Taiwan Strait throughflow across the mid-shelf area of the East China Sea. Target-oriented surveys in the 1990s and 2000s employing advanced instruments, such as drifter tracking and acoustic Doppler current profiler measurements, now provide decisive proof of the clockwise rounding of the Cheju Warm Current around Jeju-do throughout the year, of the northeastward extension of Changjiang discharge in summer, and of the presence of the Yellow Sea Warm Current only in winter. Thus, both coastal currents in shallow water and secondary branch currents of the Kuroshio (such as the Yellow Sea Warm Current) are found to significantly change from winter to summer. To better present the basic pattern of YECS circulation and its seasonality, we have constructed seasonal circulations patterns, based on review results, on the newly-compiled drifter trajectories, and on hydrographic observations. Further investigations should be carried out in future, with support of comprehensive current measurements on shelf areas and through elaborate numerical modeling.

  3. Air pollution in Accra neighborhoods: spatial, socioeconomic, and temporal patterns.

    PubMed

    Dionisio, Kathie L; Arku, Raphael E; Hughes, Allison F; Vallarino, Jose; Carmichael, Heather; Spengler, John D; Agyei-Mensah, Samuel; Ezzati, Majid

    2010-04-01

    This study examined the spatial, socioeconomic status (SES), and temporal patterns of ambient air pollution in Accra, Ghana. Over 22 months, integrated and continuous rooftop particulate matter (PM) monitors were placed at a total of 11 residential or roadside monitoring sites in four neighborhoods of varying SES and biomass fuel use. PM concentrations were highest in late December and January, due to dust blown from the Sahara. Excluding this period, annual PM(2.5) ranged from 39 to 53 microg/m(3) at roadside sites and 30 to 70 microg/m(3) at residential sites; mean annual PM(10) ranged from 80 to 108 microg/m(3) at roadside sites and 57 to 106 microg/m(3) at residential sites. The low-income and densely populated neighborhood of Jamestown/Ushertown had the single highest residential PM concentration. There was less difference across traffic sites. Daily PM increased at all sites at daybreak, followed by a mid-day peak at some sites, and a more spread-out evening peak at all sites. Average carbon monoxide concentrations at different sites and seasons ranged from 7 to 55 ppm, and were generally lower at residential sites than at traffic sites. The results show that PM in these four neighborhoods is substantially higher than the WHO Air Quality Guidelines and in some cases even higher than the WHO Interim Target 1, with the highest pollution in the poorest neighborhood.

  4. Participatory Patterns in an International Air Quality Monitoring Initiative

    PubMed Central

    Sîrbu, Alina; Becker, Martin; Caminiti, Saverio; De Baets, Bernard; Elen, Bart; Francis, Louise; Gravino, Pietro; Hotho, Andreas; Ingarra, Stefano; Loreto, Vittorio; Molino, Andrea; Mueller, Juergen; Peters, Jan; Ricchiuti, Ferdinando; Saracino, Fabio; Servedio, Vito D. P.; Stumme, Gerd; Theunis, Jan; Tria, Francesca; Van den Bossche, Joris

    2015-01-01

    The issue of sustainability is at the top of the political and societal agenda, being considered of extreme importance and urgency. Human individual action impacts the environment both locally (e.g., local air/water quality, noise disturbance) and globally (e.g., climate change, resource use). Urban environments represent a crucial example, with an increasing realization that the most effective way of producing a change is involving the citizens themselves in monitoring campaigns (a citizen science bottom-up approach). This is possible by developing novel technologies and IT infrastructures enabling large citizen participation. Here, in the wider framework of one of the first such projects, we show results from an international competition where citizens were involved in mobile air pollution monitoring using low cost sensing devices, combined with a web-based game to monitor perceived levels of pollution. Measures of shift in perceptions over the course of the campaign are provided, together with insights into participatory patterns emerging from this study. Interesting effects related to inertia and to direct involvement in measurement activities rather than indirect information exposure are also highlighted, indicating that direct involvement can enhance learning and environmental awareness. In the future, this could result in better adoption of policies towards decreasing pollution. PMID:26313263

  5. Participatory Patterns in an International Air Quality Monitoring Initiative.

    PubMed

    Sîrbu, Alina; Becker, Martin; Caminiti, Saverio; De Baets, Bernard; Elen, Bart; Francis, Louise; Gravino, Pietro; Hotho, Andreas; Ingarra, Stefano; Loreto, Vittorio; Molino, Andrea; Mueller, Juergen; Peters, Jan; Ricchiuti, Ferdinando; Saracino, Fabio; Servedio, Vito D P; Stumme, Gerd; Theunis, Jan; Tria, Francesca; Van den Bossche, Joris

    2015-01-01

    The issue of sustainability is at the top of the political and societal agenda, being considered of extreme importance and urgency. Human individual action impacts the environment both locally (e.g., local air/water quality, noise disturbance) and globally (e.g., climate change, resource use). Urban environments represent a crucial example, with an increasing realization that the most effective way of producing a change is involving the citizens themselves in monitoring campaigns (a citizen science bottom-up approach). This is possible by developing novel technologies and IT infrastructures enabling large citizen participation. Here, in the wider framework of one of the first such projects, we show results from an international competition where citizens were involved in mobile air pollution monitoring using low cost sensing devices, combined with a web-based game to monitor perceived levels of pollution. Measures of shift in perceptions over the course of the campaign are provided, together with insights into participatory patterns emerging from this study. Interesting effects related to inertia and to direct involvement in measurement activities rather than indirect information exposure are also highlighted, indicating that direct involvement can enhance learning and environmental awareness. In the future, this could result in better adoption of policies towards decreasing pollution.

  6. Participatory Patterns in an International Air Quality Monitoring Initiative.

    PubMed

    Sîrbu, Alina; Becker, Martin; Caminiti, Saverio; De Baets, Bernard; Elen, Bart; Francis, Louise; Gravino, Pietro; Hotho, Andreas; Ingarra, Stefano; Loreto, Vittorio; Molino, Andrea; Mueller, Juergen; Peters, Jan; Ricchiuti, Ferdinando; Saracino, Fabio; Servedio, Vito D P; Stumme, Gerd; Theunis, Jan; Tria, Francesca; Van den Bossche, Joris

    2015-01-01

    The issue of sustainability is at the top of the political and societal agenda, being considered of extreme importance and urgency. Human individual action impacts the environment both locally (e.g., local air/water quality, noise disturbance) and globally (e.g., climate change, resource use). Urban environments represent a crucial example, with an increasing realization that the most effective way of producing a change is involving the citizens themselves in monitoring campaigns (a citizen science bottom-up approach). This is possible by developing novel technologies and IT infrastructures enabling large citizen participation. Here, in the wider framework of one of the first such projects, we show results from an international competition where citizens were involved in mobile air pollution monitoring using low cost sensing devices, combined with a web-based game to monitor perceived levels of pollution. Measures of shift in perceptions over the course of the campaign are provided, together with insights into participatory patterns emerging from this study. Interesting effects related to inertia and to direct involvement in measurement activities rather than indirect information exposure are also highlighted, indicating that direct involvement can enhance learning and environmental awareness. In the future, this could result in better adoption of policies towards decreasing pollution. PMID:26313263

  7. Large-Scale Atmospheric Circulation Patterns Associated with Temperature Extremes as a Basis for Model Evaluation: Methodological Overview and Results

    NASA Astrophysics Data System (ADS)

    Loikith, P. C.; Broccoli, A. J.; Waliser, D. E.; Lintner, B. R.; Neelin, J. D.

    2015-12-01

    Anomalous large-scale circulation patterns often play a key role in the occurrence of temperature extremes. For example, large-scale circulation can drive horizontal temperature advection or influence local processes that lead to extreme temperatures, such as by inhibiting moderating sea breezes, promoting downslope adiabatic warming, and affecting the development of cloud cover. Additionally, large-scale circulation can influence the shape of temperature distribution tails, with important implications for the magnitude of future changes in extremes. As a result of the prominent role these patterns play in the occurrence and character of extremes, the way in which temperature extremes change in the future will be highly influenced by if and how these patterns change. It is therefore critical to identify and understand the key patterns associated with extremes at local to regional scales in the current climate and to use this foundation as a target for climate model validation. This presentation provides an overview of recent and ongoing work aimed at developing and applying novel approaches to identifying and describing the large-scale circulation patterns associated with temperature extremes in observations and using this foundation to evaluate state-of-the-art global and regional climate models. Emphasis is given to anomalies in sea level pressure and 500 hPa geopotential height over North America using several methods to identify circulation patterns, including self-organizing maps and composite analysis. Overall, evaluation results suggest that models are able to reproduce observed patterns associated with temperature extremes with reasonable fidelity in many cases. Model skill is often highest when and where synoptic-scale processes are the dominant mechanisms for extremes, and lower where sub-grid scale processes (such as those related to topography) are important. Where model skill in reproducing these patterns is high, it can be inferred that extremes are

  8. Seasonal variation of local atmospheric circulations and boundary layer structure in the Beijing-Tianjin-Hebei region and implications for air quality

    NASA Astrophysics Data System (ADS)

    Miao, Yucong; Hu, Xiao-Ming; Liu, Shuhua; Qian, Tingting; Xue, Ming; Zheng, Yijia; Wang, Shu

    2015-12-01

    The Beijing-Tianjin-Hebei (BTH) region experiences frequent heavy haze pollution in fall and winter. Pollution was often exacerbated by unfavorable atmospheric boundary layer (BL) conditions. The topography in this region impacts the BL processes in complex ways. Such impacts and implications on air quality are not yet clearly understood. The BL processes in all four seasons in BTH are thus investigated in this study using idealized simulations with the WRF-Chem model. Results suggest that seasonal variation of thermal conditions and synoptic patterns significantly modulates BL processes. In fall, with a relatively weak northwesterly synoptic forcing, thermal contrast between the mountains and the plain leads to a prominent mountain-plain breeze circulation (MPC). In the afternoon, the downward branch of the MPC, in addition to northwesterly warm advection, suppresses BL development over the western side of BTH. In the eastern coastal area, a sea-breeze circulation develops late in the morning and intensifies during the afternoon. In summer, southeasterly BL winds allow the see-breeze front to penetrate farther inland (˜150 km from the coast), and the MPC is less prominent. In spring and winter, with strong northwesterly synoptic winds, the sea-breeze circulation is confined in the coastal area, and the MPC is suppressed. The BL height is low in winter due to strong near-surface stability, while BL heights are large in spring due to strong mechanical forcing. The relatively low BL height in fall and winter may have exacerbated the air pollution, thus contributing to the frequent severe haze events in the BTH region.

  9. Pattern and molecular epidemiology of Hepatitis B virus genotypes circulating in Pakistan.

    PubMed

    Awan, Zunaira; Idrees, Muhammad; Amin, Irum; Butt, Sadia; Afzal, Samia; Akbar, Haji; Rehman, Irshad-ur; Younas, Saima; Shahid, Muhammad; Lal, Amreek; Saleem, Sana; Rauff, Bisma

    2010-12-01

    The continuously mutating nature of Hepatitis B virus (HBV) is responsible for the emergence of varying genotypes in different regions of the world affecting the disease outcome. The objective of the current study was to find out the pattern of HBV genotypes circulating in Pakistan. HBV genotypes were determined in HBV chronic patients of different age and gender from all the four different geographical regions (provinces) of Pakistan for a period of 2 years (2007-2009). Out of the total 3137 consecutive patients, 300 (175; 58.3% males and 125; 41.7% females) were randomly selected for HBV genotype A through H determination using molecular genotyping methods. Total 269 (89.6%) isolates were successfully genotyped where as 31 (10.3%) samples failed to generate a type-specific PCR band and were found untypable. Out of the successfully genotyped samples, 43 (14.3%) were with type A, 54 (18%) were with type B, 83 (27.6%) were with type C, 39 (13%) were with type D, 2 (0.6%) were with type E, 4 (1.3%) were with genotype F and total 44 (14.6%) were with mixed HBV infections. Of the mixed genotype infection cases, 16 were with genotypes A/D, 9 were B/C, six were A/D/F, five were with genotypes A/F, two were with A/B/D and B/E and one each for A/C as well as A/E genotypes. Four common genotypes of HBV found worldwide (A, B, C & D) were isolated from Pakistan along with uncommon genotypes E and F for the first time in Pakistan. Overall Genotype C is the most prevalent genotype. Genotypes B and C are predominant in Punjab & Balochistan and Khyber Pakhtoonkhwa, respectively whereas genotype A in Sindh.

  10. Recent changes in air temperature, heat waves occurrences, and atmospheric circulation in Northern Africa

    NASA Astrophysics Data System (ADS)

    Fontaine, Bernard; Janicot, Serge; Monerie, Paul-Arthur

    2013-08-01

    study documents the time evolution of air temperature and heat waves occurrences over Northern Africa for the period 1979-2011. A significant warming (1°-3°C), appearing by the mid-1960s over Sahara and Sahel, is associated with higher/lesser frequency of warm/cold temperatures, as with longer duration and higher occurrences of heat waves. Heat waves episodes of at least 4 day duration have been examined after removing the long-term evolution. These episodes are associated with specific anomalies: (i) in spring, positive low-level temperature anomalies over the Sahel and Sahara; low and midlevel cyclonic rotation over Morocco associated with a Rossby wave pattern, lessening the Harmattan; more/less atmospheric moisture westward/eastward to 0°; upward/downward anomalies above the western/eastern regions associated with the Rossby wave pattern; (ii) in summer, a similar but weaker positive low-level temperature anomaly (up to 3°C); less moisture westward to 10°W, a cyclonic anomaly in central Sahel favoring the monsoon eastward to 0° and a midlevel anticyclonic anomaly over the Western Sahara, increasing southward the flux divergence associated with the African Easterly Jet. In March-May, two to three heat waves propagate eastward. They are preceded by an abnormal warm cell over Libya and southwesterlies over the West Sahara. A large trough stands over North Atlantic while midtropospheric subsidence and anticyclonic rotation reinforce over the continent, then migrates toward the Arabian peninsula in breaking up. These signals are spatially coherent and might suggest the role of short Rossby waves with an eastward group velocity and a baroclinic mode, possibly associated with jet stream deformation.

  11. Land use changes and its impacts on air quality and atmospheric patterns

    NASA Astrophysics Data System (ADS)

    Freitas, E. D.; Mazzoli, C. R.; Martins, L. D.; Martins, J. A.; Carvalho, V.; Andrade, M.

    2013-05-01

    Possible modifications on atmospheric patterns and air quality caused by land use changes are discussed in this work. With the increasing interest in alternative energy sources, mainly due to the replacement of fossil fuels, large part of the Brazilian territory is being used for sugar cane cultivation. The resultant modifications in land use and some activities associated to this crop are studied with some detail through numerical modeling of the atmosphere. The same tool was applied to study the effect of surface type and emission sources over urban areas in the neighborhoods of the cultivated areas, in particular those located in the Metropolitan Area of Campinas, inside the state of São Paulo, Brazil. The main focus of this work was to identify some relationship between these two types of land use modification and its influence on the regional atmospheric circulation patterns and air quality over agricultural and urban areas affected by biomass burning and the traditional sources of pollutants, such as industries and vehicles. First, the effect of urban areas was analyzed and it was possible to identify typical patterns associated with urban heat islands, especially over the city of Campinas. In this region, air temperature differences up to 3 K were detected during night time. During the day, due to the atmospheric conditions of the studied period, this effect was not significant. Afterwards, the effect of sugar cane cultivated regions was discussed. The results show that the regions of sugar cane grow can significantly modify the surface energy fluxes, with direct consequences to the standards of local temperature and humidity and over nearby regions. Sensitivity tests were carried out during part of September, 2007, through the substitution of the sugar cane by a generic crop in the model, and show that during the day the cultivated areas can present temperatures up to 0,65 k higher than those in the case of the generic one. Throughout the dispersion module

  12. Graphical User Interface Development for Representing Air Flow Patterns

    NASA Technical Reports Server (NTRS)

    Chaudhary, Nilika

    2004-01-01

    In the Turbine Branch, scientists carry out experimental and computational work to advance the efficiency and diminish the noise production of jet engine turbines. One way to do this is by decreasing the heat that the turbine blades receive. Most of the experimental work is carried out by taking a single turbine blade and analyzing the air flow patterns around it, because this data indicates the sections of the turbine blade that are getting too hot. Since the cost of doing turbine blade air flow experiments is very high, researchers try to do computational work that fits the experimental data. The goal of computational fluid dynamics is for scientists to find a numerical way to predict the complex flow patterns around different turbine blades without physically having to perform tests or costly experiments. When visualizing flow patterns, scientists need a way to represent the flow conditions around a turbine blade. A researcher will assign specific zones that surround the turbine blade. In a two-dimensional view, the zones are usually quadrilaterals. The next step is to assign boundary conditions which define how the flow enters or exits one side of a zone. way of setting up computational zones and grids, visualizing flow patterns, and storing all the flow conditions in a file on the computer for future computation. Such a program is necessary because the only method for creating flow pattern graphs is by hand, which is tedious and time-consuming. By using a computer program to create the zones and grids, the graph would be faster to make and easier to edit. Basically, the user would run a program that is an editable graph. The user could click and drag with the mouse to form various zones and grids, then edit the locations of these grids, add flow and boundary conditions, and finally save the graph for future use and analysis. My goal this summer is to create a graphical user interface (GUI) that incorporates all of these elements. I am writing the program in

  13. Interannual Variability of Heat Wave in South Korea and theirs Connection with Large-Scale Atmospheric Circulation Pattern

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Seop; Lee, Myong-In

    2016-04-01

    This study investigates the interannual variation of heat wave frequency (HWF) in South Korea during the past 42 years (1973-2014) and examines its connection with large-scale atmospheric circulation changes. Korean heat waves tend to develop most frequently in late summer during July and August. The leading Empirical Orthogonal Function (EOF) accounting for 50% of the total variance shows a mono-signed pattern over South Korea, suggesting that the dominant mechanisms responsible for the heat wave are linked in a spatial scale much larger than the nation. It also exhibits a regional variation with more occurrences in the southeastern inland area. The regression of the leading principal component (PC) time series of HWF with large-scale atmospheric circulation identifies a north-south dipole pattern between the South China Sea and Northeast Asia. When this large-scale circulation mode facilitates deep convection in South China Sea, it tends to weaken moisture transport from the South China Sea to Northeast Asia. Enhanced deep convection in the South China Sea triggers a source of Rossby wave train along southerly wind that generates positive geopotential height anomalies around Korea. The anomalous high pressure pattern is accompanied by large-scale subsidence in Korea, thereby providing a favorable condition for extreme hot and dry days in Korea. This study highlights that there is a decadal change of the relationship between Korean heat waves and large-scale atmospheric circulation patterns. The tropical forcing tends to be weakened in the recent decade, with more influences from the Arctic variability from the mid-1990s.

  14. Precipitation predictability associated with tropical moisture exports and circulation patterns for a major flood in France in 1995

    NASA Astrophysics Data System (ADS)

    Lu, Mengqian; Lall, Upmanu; Schwartz, Aurélien; Kwon, HyunHan

    2013-10-01

    Atmospheric Rivers (ARs) are being increasingly identified as associated with some extreme floods. More generally, such floods may be associated with tropical moisture exports (TMEs) that exhibit relatively robust teleconnections between moisture source regions and flood regions. A large-scale flood event that persisted over Western Europe in January 1995 is studied here. During the last 10 days of the month, two rare flooding events, associated with heaviest rainfall in 150 years, occurred in two places, one over Brittany (West of France), and the second in the France-Germany border region and parts of neighboring countries. In this paper, we explore the month-long evolution of TMEs and their connection to the precipitation events that led to the Brittany event. The persistent large-scale atmospheric circulation patterns that led to the birth, death, and evolution of these TMEs as ARs with landfalls in Western Europe are identified, and the relationship of daily extreme precipitation to these patterns is examined. Singular value decomposition analysis and a generalized linear model are used to assess whether knowledge of the atmospheric circulation patterns from the prior record is useful for explaining the occurrence of their rare events. The analysis establishes the importance of both global and regional atmospheric circulation modes for the occurrence of such persistent events and the hydrologic importance of diagnosing global atmospheric moisture pathways.

  15. Trends in persistent seasonal-scale atmospheric circulation patterns responsible for precipitation and temperature extremes in California

    NASA Astrophysics Data System (ADS)

    Swain, D. L.; Horton, D. E.; Singh, D.; Diffenbaugh, N. S.

    2015-12-01

    Long-lived anomalous atmospheric circulation patterns are often associated with surface weather extremes. This is particularly true from a hydroclimatic perspective in regions that have well-defined "wet seasons," where atmospheric anomalies that persist on a seasonal scale can lead to drought or (conversely) increase the risk of flood. Recent evidence suggests that both natural variability and global warming may be responsible for spatially and temporally heterogeneous changes in Northern Hemisphere atmospheric conditions over the past several decades. In this investigation, we assess observed trends in cool-season (Oct-May) circulation patterns over the northeastern Pacific Ocean which have historically been associated with precipitation and temperature extremes in California. We find that the occurrence of certain extreme seasonal-scale atmospheric configurations has changed substantially over the 1948-2015 period, and also that there has been a trend towards amplification of the cool-season mean state in this region. Notably, patterns similar to the persistent anticyclone associated with the extremely warm and dry conditions experienced during the ongoing 2012-2015 California drought occur more frequently in the second half of the observed record. This finding highlights the importance of examining changes in extreme and/or persistent atmospheric circulation configurations, which may exhibit different responses to natural and anthropogenic forcings than the mean state.

  16. Observed and modeled patterns of circulation in a semi-enclosed bay: Ria de Vigo (NW Iberia)

    NASA Astrophysics Data System (ADS)

    Pilczynski, Krzysztof; Dubert, Jesus; Nolasco, Rita; Barton, Des; Souto Torres, Carlos

    2016-04-01

    The Ría de Vigo, as a semi-enclosed bay, belonging to the area so-called Rias Baixas, located at the northern tip of the Iberian coastal upwelling system. The circulation of the Ria de Vigo, being one of the major areas of mussels production, has become the subject of intensive research. The Ria de Vigo behaves as a partially-mixed estuary with a two-layered residual circulation, and is influenced by water exchange with the surrounding ocean. During northerly (upwelling favorable) winds, water enters into the Ria through the northern mouth and leaves through the surface layer of the southern mouth, in a double layer circulation at this mouth. Nearly opposed situation occours during downwelling favourable wind periods. Numerical models have become useful tools to study the hydrology and circulation of the Ria de Vigo. In this research we used the ROMS - AGRIF model. The implementation of several nested domains to increase the spatial resolution (up to 150m resolution) allowed solving the interactions between Ria de Vigo and surrounding coastal ocean in a realistic way. We have obtained a detailed description of the circulation with good agreement between observational data (ADCP moorings at both mouths, and weekly hydrological cruises) and predicted currents, salinity and temperature fields. Two new patterns of circulation in the Ria are revealed by our research: -In particular conditions associated with northerly wind relaxation, there are two-layer circulation occurs in both mouths of the Ria, consisting of outflow and inflow though the surface and bottom layers. This situation happens in the absence of stratification during winter. -Also during winter, one-layer circulation in the southern mouth of the Ria (typically there are two layers) can occur during long periods of persistent and strong upwelling-favourable wind. Our research has provided a detailed study of the circulation and hydrology of the Ria de Vigo, explaining specifically different mechanisms of

  17. Can large scale surface circulation changes modulate the sea surface warming pattern in the Tropical Indian Ocean?

    NASA Astrophysics Data System (ADS)

    Rahul, S.; Gnanaseelan, C.

    2016-06-01

    The increased rate of Tropical Indian Ocean (TIO) surface warming has gained a lot of attention in the recent years mainly due to its regional climatic impacts. The processes associated with this increased surface warming is highly complex and none of the mechanisms in the past studies could comprehend the important features associated with this warming such as the negative trends in surface net heat fluxes and the decreasing temperature trends at thermocline level. In this work we studied a previously unexplored aspect, the changes in large scale surface circulation pattern modulating the surface warming pattern over TIO. We use ocean reanalysis datasets and a suit of Ocean General Circulation Model (OGCM) experiments to address this problem. Both reanalysis and OGCM reveal strengthening large scale surface circulation pattern in the recent years. The most striking feature is the intensification of cyclonic gyre circulation around the thermocline ridge in the southwestern TIO. The surface circulation change in TIO is mainly associated with the surface wind changes and the geostrophic response to sea surface height decrease in the western/southwestern TIO. The surface wind trends closely correspond to SST warming pattern. The strengthening mean westerlies over the equatorial region are conducive to convergence in the central and divergence in the western equatorial Indian Ocean (IO) resulting central warming and western cooling. The resulting east west SST gradient further enhances the equatorial westerlies. This positive feedback mechanism supports strengthening of the observed SST trends in the equatorial Indian Ocean. The cooling induced by the enhanced upwelling in the west is compensated to a large extent by warming due to reduction in mixed layer depth, thereby keeping the surface temperature trends in the west to weak positive values. The OGCM experiments showed that the wind induced circulation changes redistribute the excess heat received in the western

  18. Characterization of Visual Scanning Patterns in Air Traffic Control.

    PubMed

    McClung, Sarah N; Kang, Ziho

    2016-01-01

    Characterization of air traffic controllers' (ATCs') visual scanning strategies is a challenging issue due to the dynamic movement of multiple aircraft and increasing complexity of scanpaths (order of eye fixations and saccades) over time. Additionally, terminologies and methods are lacking to accurately characterize the eye tracking data into simplified visual scanning strategies linguistically expressed by ATCs. As an intermediate step to automate the characterization classification process, we (1) defined and developed new concepts to systematically filter complex visual scanpaths into simpler and more manageable forms and (2) developed procedures to map visual scanpaths with linguistic inputs to reduce the human judgement bias during interrater agreement. The developed concepts and procedures were applied to investigating the visual scanpaths of expert ATCs using scenarios with different aircraft congestion levels. Furthermore, oculomotor trends were analyzed to identify the influence of aircraft congestion on scan time and number of comparisons among aircraft. The findings show that (1) the scanpaths filtered at the highest intensity led to more consistent mapping with the ATCs' linguistic inputs, (2) the pattern classification occurrences differed between scenarios, and (3) increasing aircraft congestion caused increased scan times and aircraft pairwise comparisons. The results provide a foundation for better characterizing complex scanpaths in a dynamic task and automating the analysis process. PMID:27239190

  19. Ambient particulate air pollution and circulating antioxidant enzymes: A repeated-measure study in healthy adults in Beijing, China.

    PubMed

    Wu, Shaowei; Wang, Bin; Yang, Di; Wei, Hongying; Li, Hongyu; Pan, Lu; Huang, Jing; Wang, Xin; Qin, Yu; Zheng, Chanjuan; Shima, Masayuki; Deng, Furong; Guo, Xinbiao

    2016-01-01

    The association of systemic antioxidant activity with ambient air pollution has been unclear. A panel of 40 healthy college students underwent repeated blood collection for 12 occasions under three exposure scenarios before and after relocating from a suburban area to an urban area in Beijing, China in 2010-2011. We measured various air pollutants including fine particles (PM2.5) and determined circulating levels of antioxidant enzymes extracellular superoxide dismutase (EC-SOD) and glutathione peroxidase 1 (GPX1) in the laboratory. An interquartile range increase of 63.4 μg/m(3) at 3-d PM2.5 moving average was associated with a 6.3% (95% CI: 0.6, 12.4) increase in EC-SOD and a 5.5% (95% CI: 1.3, 9.8) increase in GPX1. Several PM2.5 chemical constituents, including negative ions (nitrate and chloride) and metals (e.g., iron and strontium), were consistently associated with increases in EC-SOD and GPX1. Our results support activation of circulating antioxidant enzymes following exposure to particulate air pollution.

  20. Five centuries of U.S. West Coast drought: Occurrence, spatial distribution, and associated atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Wise, Erika K.

    2016-05-01

    The U.S. West Coast drought commencing in 2012 developed in association with a large, persistent high-pressure ridge linked to internal atmospheric variability. This study places the occurrence, spatial patterns, and associated circulation features of West Coast drought into a paleoclimate context through a synoptic dendroclimatology approach linking atmospheric circulation to surface hydroclimate patterns. Spatial reconstructions of upper atmosphere pressure patterns and cool-season drought show that West Coast-wide drought, although relatively rare compared to north-south dipole drought, has occurred periodically since 1500 Common Era and is consistently associated with a strong ridge centered along the Pacific Northwest coast. Atmospheric blocking is also linked to north-dry dipole droughts, while south-dry and wider Western droughts indicate La Niña-type patterns. The transition latitude between the northern and southern sides of the western precipitation dipole, important for California hydroclimate patterns, has had frequent year-to-year fluctuations but remained centered on 40°N over the past five centuries.

  1. Pressure oscillations on the surface of Gale Crater and coincident observations of global circulation patterns.

    NASA Astrophysics Data System (ADS)

    De La Torre Juarez, M.; Kass, D. M.; Haberle, R. M.; Gómez-Elvira, J.; Harri, A. M.; Kleinboehl, A.; Kahanpää, H.; Kahre, M. A.; Lemmon, M. T.; Martín-Torres, J.; Newman, C. E.; Rafkin, S. C.; Rodriguez-Manfredi, J. A.; Peinado, V.; Vasavada, A. R.; Zorzano, M. P.

    2014-12-01

    The annual cycle of mean diurnal surface pressures observed by Curiosity's Rover Environmental Monitoring Station (REMS) has shown oscillations after two Southern Hemispheric storms that occurred before the annual pressure maxima and minima of the dusty season (Ls~250 and 330). The oscillations had a period of ~7 sols and were less visible or absent during the dust free seasons (Ls ~ 0). Martian airborne dust alters the atmosphere's response to solar radiation and the resulting heating profiles. Since the atmospheric circulation responds to thermal forcing by the Sun, atmospheric dust can alter the large-scale circulation. We use coincident global observations by the Mars Climate Sounder (MCS) to examine the global circulation. We find that the observed surface pressure oscillations relate to oscillations of the Hadley cell. We also analyze the potential impacts of these coupled oscillations especially as related to traveling waves and thermal tides.

  2. Impact of synoptic weather patterns and inter-decadal climate variability on air quality in the North China Plain during 1980-2013

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Ding, Aijun; Mao, Huiting; Nie, Wei; Zhou, Derong; Liu, Lixia; Huang, Xin; Fu, Congbin

    2016-01-01

    Potential relationships between air quality, synoptic weather patterns, and the East Asian Monsoon (EAM) over the North China Plain (NCP) were examined during the time period of 1980-2013 using a weather typing technique and ground-based air pollution index (API) data from three cities: Beijing, Tianjin and Shijiazhuang. Using the Kirchhofer method, circulation patterns during the 34-yr study period were classified into 5 categories, which were further used to understand the quantitative relationship between weather and air quality in NCP. The highest API values were associated with a stagnant weather condition when wide-spread stable conditions controlled most part of NCP, while westerly and southerly wind flowed over the northern and eastern part of this region, resulting in both the regional transport and local build-up of air pollutants. Under the continuous control of this weather pattern, API values were found to increase at a rate of 8.5 per day on average. Based on the qualitative and quantitative analysis, a significant correlation was found between the strength of EAM and inter-annual variability of frequencies of the weather patterns. The strengthening of summer/winter monsoon could increase the frequency of occurrence of cyclone/anticyclone related weather patterns. Time series of climate-induced variability in API over the 34 years were reconstructed based on the quantitative relationship between API and predominant weather patterns during 2001-2010. Significant connections between EAM and reconstructed API were found on both the inter-annual and inter-decadal scales. In winter and summer, strengthening/weakening of EAM, which was generally associated with the change of the representative circulation patterns, could improve/worsen air quality in this region.

  3. Future Changes Projections of Atmospheric Circulation and Precipitation and Temperature Patterns Over South America in Austral Summer

    NASA Astrophysics Data System (ADS)

    Shimizu, M. H.; Cavalcanti, I. F.

    2012-12-01

    Atmospheric circulation is primarily driven by temperature gradients across the globe due to differential heating of Earth's surface which leads to a surplus of energy in the tropics and a deficit in the high latitudes. However, due to global warming, changes in atmospheric circulation are expected, which could result in modifications also in precipitation pattern. There are some evidences of changes in atmospheric circulation, such as the expansion of tropical belt and the poleward shift of large-scale atmospheric circulation systems, such as jet streams. These changes can be enhanced in a scenario with increasing greenhouse gases concentration. The objective of this study was to analyze future changes of atmospheric circulation and precipitation and temperature patterns in the austral summer over South America under Representative Pathway Concentration 8.5 (RCP 8.5) emission scenario. This evaluation was made according to model projections based on the coordinated climate change experiments defined by Coupled Model Intercomparison Project phase 5 (CMIP5). Historical simulations were used to evaluate model performance in reproduce main climatic features over South America in the Austral Summer. This analysis showed that some models perform better than others, with a wide range of difference between simulations and Global Precipitation Climatology Project (GPCP) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data sets. In general, the models captured the main features of Austral Summer such as the northwest-southeast precipitation band associated with the South Atlantic Convergence Zone (SACZ) and the anticyclonic circulation at high levels related to Bolivian High. The projections from different models pointed out in general to a reduction of precipitation, however the signal was not the same over all the continent and for all models. For example, Met Office's HadGEM2-ES projection indicated a reduction of precipitation in most of

  4. Analysis of long-range transport of particulate matters in connection with air circulation over Central and Eastern part of Europe

    NASA Astrophysics Data System (ADS)

    Stefan, Sabina; Necula, Cristian; Georgescu, Florinela

    The aim of this paper is to establish a practical methodology for examining the long-range transport of particulate matters (PM), named TSP. The daily concentration values of TSP from years 2001 and 2002, for three sites, Baia Mare (RO), Vienna (AU), Aosta (IT), were analyzed. In order to connect the main air circulation types with the aerosol concentrations at the selected sites, the catalogues of Circulation and Weather type Classification (COST733) were used. Spectral analysis was made using spectrum software based on Lomb-Scargle periodograms, and multiresolution analysis (MRA) technique based on Maximal Overlap Discrete Wavelet Transform (MODWT) with Fejer-Korovkin in 22 points wavelet filter (waveslim package). Spectral analysis shows a dominant one-year periodicity for all the time series with a variance around 22% for each time series. In addition, several winters TSP pollution episodes from each city were analyzed using a back trajectory model (HYSPLIT4), in order to compare with the resulted air circulation types. Two important concluding remarks emerge: (i) the Eastern part of Europe shows a dominant easterly air circulation and central Europe is characterized by south-west air circulations, which drive the maxima of pollutant concentrations; (ii) the choice of the domain for analysis of the circulation types is very important.

  5. Absolute Interrogative Intonation Patterns in Buenos Aires Spanish

    ERIC Educational Resources Information Center

    Lee, Su Ar

    2010-01-01

    In Spanish, each uttered phrase, depending on its use, has one of a variety of intonation patterns. For example, a phrase such as "Maria viene manana" "Mary is coming tomorrow" can be used as a declarative or as an absolute interrogative (a yes/no question) depending on the intonation pattern that a speaker produces. Patterns of usage also…

  6. Patterns of orographic uplift in the Sierra Nevada and their relationship to upper-level atmospheric circulation

    USGS Publications Warehouse

    Aguado, Edward; Cayan, Daniel R.; Reece, Brian D.; Riddle, Larry

    1993-01-01

    We examine monthly and seasonal patterns of precipitation across various elevations of the eastern Central Valley of California and the Sierra Nevada. A measure of the strength of the orographic effect called the “precipitation ratio” is calculated, and we separate months into four groups based on being wet or dry and having low or high precipitation ratios. Using monthly maps of mean 700-mb height anomalies, we describe the northern hemisphere mid-tropospheric circulation patterns associated with each of the four groups. Wet months are associated with negative height anomalies over the eastern Pacific, as expected. However, the orientation of the trough is different for years with high and low precipitation ratios. Wet months with high ratios typically have circulation patterns factoring a west-southwest to east-northeast storm track from around the Hawaiian Islands to the Pacific Northwest of the United States. Wet months with low precipitation ratios are associated with a trough centered near the Aleutians and a northwest to southeast storm track. Dry months are marked by anticyclones in the Pacific, but this feature is more localized to the eastern Pacific for months with low precipitation ratios than for those with high ratios. Using precipitation gauge and snow course data from the American River and Truckee-Tahoe basins, we determined that the strength of the orographic effect on a seasonal basis is spatially coherent at low and high elevations and on opposite sides of the Sierra Nevada crestline.

  7. Changes in air flow patterns using surfactants and thickeners during air sparging: bench-scale experiments.

    PubMed

    Kim, Juyoung; Kim, Heonki; Annable, Michael D

    2015-01-01

    Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating.

  8. Changes in air flow patterns using surfactants and thickeners during air sparging: bench-scale experiments.

    PubMed

    Kim, Juyoung; Kim, Heonki; Annable, Michael D

    2015-01-01

    Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating. PMID:25462638

  9. Changes in air flow patterns using surfactants and thickeners during air sparging: Bench-scale experiments

    NASA Astrophysics Data System (ADS)

    Kim, Juyoung; Kim, Heonki; Annable, Michael D.

    2015-01-01

    Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating.

  10. Modeling circulation patterns induced by spatial cross-shore wind variability in a small-size coastal embayment

    NASA Astrophysics Data System (ADS)

    Cerralbo, Pablo; Espino, Manuel; Grifoll, Manel

    2016-08-01

    This contribution shows the importance of the cross-shore spatial wind variability in the water circulation in a small-sized micro-tidal bay. The hydrodynamic wind response at Alfacs Bay (Ebro River delta, NW Mediterranean Sea) is investigated with a numerical model (ROMS) supported by in situ observations. The wind variability observed in meteorological measurements is characterized with meteorological model (WRF) outputs. From the hydrodynamic simulations of the bay, the water circulation response is affected by the cross-shore wind variability, leading to water current structures not observed in the homogeneous-wind case. If the wind heterogeneity response is considered, the water exchange in the longitudinal direction increases significantly, reducing the water exchange time by around 20%. Wind resolutions half the size of the bay (in our case around 9 km) inhibit cross-shore wind variability, which significantly affects the resultant circulation pattern. The characteristic response is also investigated using idealized test cases. These results show how the wind curl contributes to the hydrodynamic response in shallow areas and promotes the exchange between the bay and the open sea. Negative wind curl is related to the formation of an anti-cyclonic gyre at the bay's mouth. Our results highlight the importance of considering appropriate wind resolution even in small-scale domains (such as bays or harbors) to characterize the hydrodynamics, with relevant implications in the water exchange time and the consequent water quality and ecological parameters.

  11. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    NASA Technical Reports Server (NTRS)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; Diskin, Glenn S.; Dickerson, Russell R.

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  12. An objective definition of air mass types affecting Athens, Greece; the corresponding atmospheric pressure patterns and air pollution levels.

    PubMed

    Sindosi, O A; Katsoulis, B D; Bartzokas, A

    2003-08-01

    This work aims at defining characteristic air mass types that dominate in the region of Athens, Greece during the cold (November-March) and the warm (May-September) period of the year and also at evaluating the corresponding concentration levels of the main air pollutants. For each air mass type, the mean atmospheric pressure distribution (composite maps) over Europe and the Mediterranean is estimated in order to reveal the association of atmospheric circulation with air pollution levels in Athens. The data basis for this work consists of daily values of thirteen meteorological and six pollutant parameters covering the period 1993-97. The definition of the characteristic air mass types is attempted objectively by using the methods of Factor Analysis and Cluster Analysis. The results show that during the cold period of the year there are six prevailing air mass types (at least 3% of the total number of days) and six infrequent ones. The examination of the corresponding air pollution concentration levels shows that the primary air pollutants appear with increased concentrations when light or southerly winds prevail. This is usually the case when a high pressure system is located over the central Mediterranean or a low pressure system lays over south Italy, respectively. Low levels of the primary pollutants are recorded under northeasterly winds, mainly caused by a high pressure system over Ukraine. During the warm period of the year, the southwestern Asia thermal low and the subtropical anticyclone of the Atlantic Ocean affect Greece. Though these synoptic systems cause almost stagnant conditions, four main air mass types are dominant and ten others, associated with extreme weather, are infrequent. Despite the large amounts of total solar radiation characterizing this period, ozone concentrations remain at low levels in central Athens because of its destruction by nitric oxide.

  13. DNS of scalar transfer across an air-water interface during inception and growth of Langmuir circulation

    NASA Astrophysics Data System (ADS)

    Hafsi, Amine; Tejada-Martinez, Andres; Veron, Fabrice; Ma, Yi; USF/UDEL Collaboration

    2015-11-01

    Upon a blowing of a wind over an initially quiescent air-sea interface, first short capillary waves are generated which in time coexist with longer waves as part of a broad spectrum of waves. The interaction between the Stokes drift velocity induced by surface gravity waves and the mean current induced by surface wind stress leads to Langmuir turbulence (LT) characterized by Langmuir circulation (LC) consisting of parallel downwind-elongated, counter rotating vortices roughly aligned in the direction of the wind. The typical length scale of LC ranges from several centimeters when short capillary waves first appear up to tens of meters when the spectrum of waves broadens. Results are presented from direct numerical simulation (DNS) of an initially quiescent coupled air-water interface driven by an air flow with free stream speed of 5 m/s. Cases with a freely deforming interface (characterized by gravity-capillary waves giving rise to small-scale LC) and with the interface intentionally held fixed (i.e. without LC) will be compared to understand the mechanisms by which the LT enhances scalar transfer from the airside to the waterside and bulk concentration throughout the water column. Time-permitting, we will compare our results with available laboratory physical experiments.

  14. View-Angle Dependent AIRS Cloud Radiances and Fluctuations: Implications of Organized Cloud Structures for Tropical Circulations

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Gong, Jie

    2012-01-01

    Interactions between wave dynamics and moisture generate clouds in a wide range of scales. Organized cloud structures produce statistically asymmetric radiances and perturbations in AIRS and AMSU-B measurements. With high resolution (approx.14 km beamwidth) and high-sensitivity instruments, these wave-modulated cloud structures can be readily detected from calibrated Levell radiance data. In this study we analyzed eight-year (2003 - 2010) statistics of AIRS cloud-induced radiances and found that in tropical convective regions the ascending (13:30 LST) measurements reveal higher view-angle asymmetry in cloud radiance than the descending (1:30 LST). The daytime asymmetry suggests 10% more cloudiness when the instrument views east, implying tilted and banded structures in most of the anvil clouds to which AIRS is sensitive. Such banded cloud structures are likely a manifestation of embedded westward propagating gravity waves in tropical convective systems. More importantly, organized cloud structures carry asymmetric momentum fluxes in addition to energy fluxes, which must be taken into account for modeling wave-wave and wave-mean flow interactions in tropical circulations.

  15. CFD analyses of natural circulation in the air-cooled reactor cavity cooling system

    SciTech Connect

    Hu, R.; Pointer, W. D.

    2013-07-01

    The Natural Convection Shutdown Heat Removal Test Facility (NSTF) is currently being built at Argonne National Laboratory, to evaluate the feasibility of the passive Reactor Cavity Cooling System (RCCS) for Next Generation Nuclear Plant (NGNP). CFD simulations have been applied to evaluate the NSTF and NGNP RCCS designs. However, previous simulations found that convergence was very difficult to achieve in simulating the complex natural circulation. To resolve the convergence issue and increase the confidence of the CFD simulation results, additional CFD simulations were conducted using a more detailed mesh and a different solution scheme. It is found that, with the use of coupled flow and coupled energy models, the convergence can be greatly improved. Furthermore, the effects of convection in the cavity and the effects of the uncertainty in solid surface emissivity are also investigated. (authors)

  16. Heat fluxes and roll circulations over the western Gulf Stream during an intense cold-air outbreak

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Ferguson, Michael P.

    1991-01-01

    Turbulence and heat fluxes in the marine atmospheric boundary layer (MABL) for three aircraft stacks near the western Gulf Stream front, observed during the Genesis of Atlantic Lows Experiment (GALE) January 28, 1986 cold-air outbreak, has been studied using mixed-layer scaling. The GOES image and stability parameter indicates that these three stacks were in the roll vortex regime. The turbulence structure in the MABL is studied for this case, as well as the significance of roll vortices to heat fluxes. The roll circulations are shown to contribute significantly to the sensible (temperature) and latent heat (moisture) fluxes with importance increasing upward. The results suggest that the entrainment at the MABL top might affect the the budgets of temperature and humidity fluxes in the lower MABL, but not in the unstable surface layer.

  17. The effect of clear-air turbulence on a model of the general circulation of the atmosphere

    NASA Technical Reports Server (NTRS)

    Heck, W. J.; Panofsky, H. A.; Bender, M. A.

    1977-01-01

    Mixing coefficients due to clear-air turbulence are estimated from turbulence observations from aircraft, and from large-scale dissipation estimates from the large-scale energy budgets. Maximum coefficients occur near middle-latitude jet streams, and eddy viscosity there is of order of 10 sq m/sec; eddy conductivity is estimated to be about ten times smaller. These coefficients are introduced into the 12-layer general circulation model of the National Center of Atmospheric Research. They produce an apparently significant, though small reduction in maximum speed of the jet, and a reduction in eddy energy. Further, the stratospheric polar-night jet is produced at about the correct location with about the correct intensity.

  18. Preparation, characterization, and photocatalytic studies on anatase nano-TiO{sub 2} at internal air lift circulating photocatalytic reactor

    SciTech Connect

    Xu, Hang Li, Mei; Jun, Zhang

    2013-09-01

    Graphical abstract: The micro morphological structure of the nano-TiO{sub 2} particles was also observed with TEM, as shown in figure. The TEM images clearly exhibited the homogeneous microstructure of particles with a size of around 10–15 nm. - Highlights: • Nano-TiO{sub 2} was prepared by complex techniques of sol–gel, micro-emulsion and solvent thermal. • The size of TiO{sub 2} was nano level and uniformity. • Nano-TiO{sub 2} exhibited high photo-catalytic activity at internal air lift circulating reactor. • The best nano-TiO{sub 2} dosage was obtained. - Abstract: Anatase nano-titania (TiO{sub 2}) powder was prepared by using a sol–gel process mediated in reverse microemulsion combined with a solvent thermal technique. The structures of the obtained TiO{sub 2} were characterized by TG-DSC, XRD, TEM. The photocatalytic decomposition of methylene blue (MB) on nano-TiO{sub 2} was studied by using an internal air lift circulating photocatalytic reactor. The results show that the anatase structure appears in the calcination temperature range of 400–510 °C, while the transformation of anatase into rutile takes place above 510 °C. The homogeneous microstructure of nano-TiO{sub 2} particles was obtained with a size of around 10–15 nm. In the photocatalytic performance, degradation process follows pseudo first order kinetics with different dosages of photocatalyst and initial MB concentrations and optimal TiO{sub 2} dosage is 0.1 g/L with neutral medium.

  19. The air-sea transformation and diapycnal overturning circulation within the Nordic Seas

    NASA Astrophysics Data System (ADS)

    Isachsen, P. E.; Nøst, O. A.

    2012-04-01

    Air-sea flux climatologies and reanalyzes show that the bulk of the oceanic heat and buoyancy loss over the Nordic Seas takes place over interior regions not easily accessible by the time-mean large-scale currents. Eddy transport of heat and buoyancy, from the boundary currents and into the deep basins, is thought to be a key mechanism. Here we use gridded observations, theory and a modern parametrization of eddy transport to quantify the buoyancy budget of this region. The calculations confirm that mean currents are unable to explain the air-sea transformation that takes place over the interior basins of the Nordic Seas and that eddy transport instead dominates. The parametrization of eddy transport also suggests a significant overturning cell between the eastern and western parts of the Nordic Seas. This cell is, however, unaccounted for in the remaining data sets studied here.

  20. [Serological evidence of St. Louis encephalitis virus circulation in birds from Buenos Aires City, Argentina].

    PubMed

    Beltrán, Fernando J; Díaz, Luis A; Konigheim, Brenda; Molina, José; Beaudoin, Juan B; Contigiani, Marta; Spinsanti, Lorena I

    2015-01-01

    Our goal was to determine the presence of neutralizing antibodies against St. Louis encephalitis virus (SLEV) and West Nile virus (WNV) in sera of wild and domestic birds from Buenos Aires City, Argentina. From October 2012 to April 2013, 180 samples were collected and processed by the microneutralization technique. A 7.2% of the sampled birds were seropositive for SLEV, while no seropositive birds for WNV were detected.

  1. Variation in spatial pattern of criteria air pollutants before and during initial rain of monsoon.

    PubMed

    Ravindra, Khaiwal; Mor, Suman; Ameena; Kamyotra, J S; Kaushik, C P

    2003-09-01

    Spatial patterns of various criteria air pollutants, like SO2, NO2, O3, and TSP were studied at Shahdara National Ambient Air Quality Monitoring station in Delhi (India) in July 1999. The minimum pollutant concentrations were observed during morning hours, whereas the highest concentrations were found during the late night hours, which seem to be related with the vehicular emission. Pre-monsoon daily ambient air quality spatial pattern was compared with the spatial pattern during initial and subsequent rain shower of monsoon. These spatial patterns were found to be essentially the same before and during rain, however a significant decrease in SO2, NO2 and TSP concentrations (40-45%) was observed after initial and subsequent rains of the monsoon, demonstrating the importance of rainfall in the scavenging of these criteria air pollutants.

  2. Air temperature variations on the Atlantic - Arctic boundary since 1802: the low-frequency pattern and ocean teleconnections

    NASA Astrophysics Data System (ADS)

    Wood, K. R.; Overland, J. E.; Jónsson, T.; Smoliak, B. V.

    2010-12-01

    A two-hundred year instrumental record of annual surface air temperature (SAT) in the Atlantic - Arctic boundary region was reconstructed from four station-based composite time series (Fig. 1). Credibility is supported by ice core records, other temperature proxies, and historical evidence. This record (designated TNA) provides new perspective on past climate fluctuations in a region where pivotal climate system processes occur and where unexplained low-frequency variations were observed during the 20th century. TNA shows that the low-frequency pattern of the 20th century does not have a clear analog in the previous century. During the 19th century decadal-scale climate fluctuations occurred in irregular episodes; none were as distinctive as the early 20th century warming event (~1920 to mid-century), which is the most striking historical feature in the record. Evidence of a strong teleconnection between TNA and SST anomalies in the western boundary current - southern recirculation gyre (WBC) region of the North Atlantic Ocean provides an opportunity to reframe the problem of low-frequency variability in the region in terms tractable to theory and empirical investigation. Positive fluctuations in both TNA (and by extension other climate variables associated with it) and SST in the WBC region could be initiated by persistent variations in the large-scale atmospheric circulation that promote the advection of warm maritime air into the Atlantic - Arctic region and simultaneously limit flux-induced cooling in the Nordic Seas and the WBC/recirculation gyre region. This leads to enhanced ocean heat storage in both regions and may consequently reinforce anomalous atmospheric circulation patterns like those observed during the early 20th century warming event. Figure 1. Extended annual mean SAT record for the Atlantic - Arctic boundary region (TNA). The early 20th century warming (ETCW) episode is marked. Regions represented by station-based composite SAT records used in

  3. Effect of air-flow on the evaluation of refractive surgery ablation patterns.

    PubMed

    Dorronsoro, Carlos; Schumacher, Silvia; Pérez-Merino, Pablo; Siegel, Jan; Mrochen, Michael; Marcos, Susana

    2011-02-28

    An Allegretto Eye-Q laser platform (Wavelight GmbH, Erlangen, Germany) was used to study the effect of air-flow speed on the ablation of artificial polymer corneas used for testing refractive surgery patterns. Flat samples of two materials (PMMA and Filofocon A) were ablated at four different air flow conditions. The shape and profile of the ablated surfaces were measured with a precise non-contact optical surface profilometer. Significant asymmetries in the measured profiles were found when the ablation was performed with the clinical air aspiration system, and also without air flow. Increasing air-flow produced deeper ablations, improved symmetry, and increased the repeatability of the ablation pattern. Shielding of the laser pulse by the plume of smoke during the ablation of plastic samples reduced the central ablation depth by more than 40% with no-air flow, 30% with clinical air aspiration, and 5% with 1.15 m/s air flow. A simple model based on non-inertial dragging of the particles by air flow predicts no central shielding with 2.3 m/s air flow, and accurately predicts (within 2 μm) the decrease of central ablation depth by shielding. The shielding effects for PMMA and Filofocon A were similar despite the differences in the ablation properties of the materials and the different full-shielding transmission coefficient, which is related to the number of particles ejected and their associated optical behavior. Air flow is a key factor in the evaluation of ablation patterns in refractive surgery using plastic models, as significant shielding effects are found with typical air-flow levels used under clinical conditions. Shielding effects can be avoided by tuning the air flow to the laser repetition rate.

  4. Influence of forced internal air circulation on airflow distribution and heat transfer in a gas double-dynamic solid-state fermentation bioreactor.

    PubMed

    Chen, Hongzhang; Qin, Lanzhi; Li, Hongqiang

    2014-02-01

    Internal air circulation affects the temperature field distribution in a gas double-dynamic solid-state fermentation bioreactor (GDSFB). To enhance heat transfer through strengthening internal air circulation in a GDSFB, we put an air distribution plate (ADP) into the bioreactor and studied the effects of forced internal air circulation on airflow, heat transfer, and cellulase activity of Trichoderma viride L3. Results showed that ADP could help form a steady and uniform airflow distribution, and with gas-guide tubes, air reversal was formed inside the bioreactor, thus resulting in a smaller temperature difference between medium and air by enhancing convective heat transfer inside the bioreactor. Using an ADP of 5.35 % aperture ratio caused a 1 °C decrease in the average temperature difference during the solid-state fermentation process of T. viride L3. Meanwhile, the cellulase activity of T. viride L3 increased by 13.5 %. The best heat-transfer effect was attained when using an ADP of 5.35 % aperture ratio and setting the fan power to 125 V (4.81 W) in the gas double-dynamic solid-state fermentation (GDSF) process. An option of suitable aperture ratio and fan power may be conducive to ADPs' industrial amplification.

  5. Influence of forced internal air circulation on airflow distribution and heat transfer in a gas double-dynamic solid-state fermentation bioreactor.

    PubMed

    Chen, Hongzhang; Qin, Lanzhi; Li, Hongqiang

    2014-02-01

    Internal air circulation affects the temperature field distribution in a gas double-dynamic solid-state fermentation bioreactor (GDSFB). To enhance heat transfer through strengthening internal air circulation in a GDSFB, we put an air distribution plate (ADP) into the bioreactor and studied the effects of forced internal air circulation on airflow, heat transfer, and cellulase activity of Trichoderma viride L3. Results showed that ADP could help form a steady and uniform airflow distribution, and with gas-guide tubes, air reversal was formed inside the bioreactor, thus resulting in a smaller temperature difference between medium and air by enhancing convective heat transfer inside the bioreactor. Using an ADP of 5.35 % aperture ratio caused a 1 °C decrease in the average temperature difference during the solid-state fermentation process of T. viride L3. Meanwhile, the cellulase activity of T. viride L3 increased by 13.5 %. The best heat-transfer effect was attained when using an ADP of 5.35 % aperture ratio and setting the fan power to 125 V (4.81 W) in the gas double-dynamic solid-state fermentation (GDSF) process. An option of suitable aperture ratio and fan power may be conducive to ADPs' industrial amplification. PMID:24347160

  6. Global patterns and vigor of ventilated hydrothermal circulation through young seafloor

    NASA Astrophysics Data System (ADS)

    Hasterok, D.

    2013-10-01

    Using an updated global heat flow dataset with >14 000 oceanic measurements, we revise the estimated global power deficit due to ventilated hydrothermal circulation. This study differs from previous estimates by taking into account (1) non-Gaussian statistics, (2) an improved seafloor age model, (3) a new plate cooling model calibrated directly to heat flow, and (4) the effect of sediment cover on the heat flow deficit and ventilated cutoff age. We obtain the maximum heat flow deficit (difference between predicted and observed) when the data are separated by seafloor areas with <400 m and ⩾400 m of sediment cover. The estimated power deficit (integrated heat flow deficit with respect to area) for areas of thin (<400 m) sediment cover is 7.8 TW and for areas of thick (⩾400 m) is 0.2 TW. The total power deficit, 8.0 TW with 50% of estimates falling between 5.0 and 10.0 TW, represents a ˜30% reduction in magnitude compared with previous heat flow and fluid flow based estimates. Regions with thick, ⩾400 m, sediment cover experience half the heat flow deficit for one-third of the duration (25 Ma) of regions with thin sediment cover (75 Ma). Based on this study, vigorous fluid exchange between the oceans and seafloor redistributes ˜30% of heat lost through young oceanic crust.

  7. Analysis of different intraseasonal patterns of large-scale circulation over the Amazon

    NASA Astrophysics Data System (ADS)

    de Oliveira, C. P.; Ambrizzi, T.; Aimola, L. D.

    2014-12-01

    It is well known that the large-scale equatorial circulation known as the Madden-Julian Oscillation (MJO) has an important impact on the convective activity over South America. The Bolivian high is an upper-level (200 hPa) anticyclone that develops during the summer over the Bolivian Altiplano, a high plateau region of the Central Andes. The position and intensity of this high-pressure cell has been related to the seasonal variation in Amazonian rainfall. This study used the Real-time Multivariate MJO index created by Wheeler and Hendon to examine the impacts and intensification of Bolivian high using daily rainfall data from Tropical Rainfall Measuring Mission (TRMM) and 6-hourly atmospheric fields from the ECMWF Interim reanalysis (ERA Interim). Enhance of precipitation filtered for 20-100-day during 3 to 6 MJO phase is accompanied by a significant suppression of high level zonal winds near northern South Atlantic coast and vice versa, i.e., suppressed precipitation for the same filtered data is associated with an enhancement of the wind near South Atlantic coast, for 8 to 1 phase. Intensification and positioning slightly more southwest of the Bolivian high was observed when there was an increase in convection associated with MJO. This convection enhancement increases the magnitude of the divergence at high levels that consequently favored convection.

  8. Ventilation patterns of the songbird lung/air sac system during different behaviors

    PubMed Central

    Mackelprang, Rebecca; Goller, Franz

    2013-01-01

    SUMMARY Unidirectional, continuous airflow through the avian lung is achieved through an elaborate air sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various air sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of air sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior air sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of airflow and modulation of ventilation in the avian respiratory system. PMID:23788706

  9. Ventilation patterns of the songbird lung/air sac system during different behaviors.

    PubMed

    Mackelprang, Rebecca; Goller, Franz

    2013-10-01

    Unidirectional, continuous airflow through the avian lung is achieved through an elaborate air sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various air sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of air sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior air sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of airflow and modulation of ventilation in the avian respiratory system.

  10. An evaluation of WRF's ability to reproduce the surface wind over complex terrain based on typical circulation patterns

    NASA Astrophysics Data System (ADS)

    Jiménez, P. A.; Dudhia, J.; González-Rouco, J. F.; Montávez, J. P.; García-Bustamante, E.; Navarro, J.; Vilã-Guerau de Arellano, J.; Muñoz-Roldán, A.

    2013-07-01

    The performance of the Weather Research and Forecasting (WRF) model to reproduce the surface wind circulations over complex terrain is examined. The atmospheric evolution is simulated using two versions of the WRF model during an over 13 year period (1992 to 2005) over a complex terrain region located in the northeast of the Iberian Peninsula. A high horizontal resolution of 2km is used to provide an accurate representation of the terrain features. The multiyear evaluation focuses on the analysis of the accuracy displayed by the WRF simulations to reproduce the wind field of the six typical wind patterns (WPs) identified over the area in a previous observational work. Each pattern contains a high number of days which allows one to reach solid conclusions regarding the model performance. The accuracy of the simulations to reproduce the wind field under representative synoptic situations, or pressure patterns (PPs), of the Iberian Peninsula is also inspected in order to diagnose errors as a function of the large-scale situation. The evaluation is accomplished using daily averages in order to inspect the ability of WRF to reproduce the surface flow as a result of the interaction between the synoptic scale and the regional topography. Results indicate that model errors can originate from problems in the initial and lateral boundary conditions, misrepresentations at the synoptic scale, or the realism of the topographic features.

  11. Spatial and temporal air quality pattern recognition using environmetric techniques: a case study in Malaysia.

    PubMed

    Syed Abdul Mutalib, Sharifah Norsukhairin; Juahir, Hafizan; Azid, Azman; Mohd Sharif, Sharifah; Latif, Mohd Talib; Aris, Ahmad Zaharin; Zain, Sharifuddin M; Dominick, Doreena

    2013-09-01

    The objective of this study is to identify spatial and temporal patterns in the air quality at three selected Malaysian air monitoring stations based on an eleven-year database (January 2000-December 2010). Four statistical methods, Discriminant Analysis (DA), Hierarchical Agglomerative Cluster Analysis (HACA), Principal Component Analysis (PCA) and Artificial Neural Networks (ANNs), were selected to analyze the datasets of five air quality parameters, namely: SO2, NO2, O3, CO and particulate matter with a diameter size of below 10 μm (PM10). The three selected air monitoring stations share the characteristic of being located in highly urbanized areas and are surrounded by a number of industries. The DA results show that spatial characterizations allow successful discrimination between the three stations, while HACA shows the temporal pattern from the monthly and yearly factor analysis which correlates with severe haze episodes that have happened in this country at certain periods of time. The PCA results show that the major source of air pollution is mostly due to the combustion of fossil fuel in motor vehicles and industrial activities. The spatial pattern recognition (S-ANN) results show a better prediction performance in discriminating between the regions, with an excellent percentage of correct classification compared to DA. This study presents the necessity and usefulness of environmetric techniques for the interpretation of large datasets aiming to obtain better information about air quality patterns based on spatial and temporal characterizations at the selected air monitoring stations.

  12. Snowfall in the Northwest Iberian Peninsula: Synoptic Circulation Patterns and Their Influence on Snow Day Trends

    PubMed Central

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

    2014-01-01

    In recent decades, a decrease in snowfall attributed to the effects of global warming (among other causes) has become evident. However, it is reasonable to investigate meteorological causes for such decrease, by analyzing changes in synoptic scale patterns. On the Iberian Peninsula, the Castilla y León region in the northwest consists of a central plateau surrounded by mountain ranges. This creates snowfalls that are considered both an important water resource and a transportation risk. In this work, we develop a classification of synoptic situations that produced important snowfalls at observation stations in the major cities of Castilla y León from 1960 to 2011. We used principal component analysis (PCA) and cluster techniques to define four synoptic patterns conducive to snowfall in the region. Once we confirmed homogeneity of the series and serial correlation of the snowfallday records at the stations from 1960 to 2011, we carried out a Mann-Kendall test. The results show a negative trend at most stations, so there are a decreased number of snowfall days. Finally, variations in these meteorological variables were related to changes in the frequencies of snow events belonging to each synoptic pattern favorable for snowfall production at the observatory locations. PMID:25152912

  13. Snowfall in the northwest Iberian Peninsula: synoptic circulation patterns and their influence on snow day trends.

    PubMed

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

    2014-01-01

    In recent decades, a decrease in snowfall attributed to the effects of global warming (among other causes) has become evident. However, it is reasonable to investigate meteorological causes for such decrease, by analyzing changes in synoptic scale patterns. On the Iberian Peninsula, the Castilla y León region in the northwest consists of a central plateau surrounded by mountain ranges. This creates snowfalls that are considered both an important water resource and a transportation risk. In this work, we develop a classification of synoptic situations that produced important snowfalls at observation stations in the major cities of Castilla y León from 1960 to 2011. We used principal component analysis (PCA) and cluster techniques to define four synoptic patterns conducive to snowfall in the region. Once we confirmed homogeneity of the series and serial correlation of the snowfallday records at the stations from 1960 to 2011, we carried out a Mann-Kendall test. The results show a negative trend at most stations, so there are a decreased number of snowfall days. Finally, variations in these meteorological variables were related to changes in the frequencies of snow events belonging to each synoptic pattern favorable for snowfall production at the observatory locations.

  14. [PATTERNS IN CIRCULATION AND TRANSMISSION OF MARINE BIRD PARASITES IN HIGH ARCTIC: A CASE OF ACANTHOCEPHALAN POLYMORPHUS PHIPPSI (PALAEACANTHOCEPHALA, POLYMORPHIDAE)].

    PubMed

    Galaktionov, K V; Atrashkevich, G I

    2015-01-01

    This study, based on the materials on parasitic infection of marine birds and invertebrates in Frantz Josef Land (FJL) collected in 1991-1993, focussed on the acanthocephalan Polymorphus phippsi. We identified this parasite, confirmed its species status and analysed its circulation and transmission patterns in high Arctic. The causes of its erroneous identification as P. minutus in several studies were also examined. In contrast to P. minutus, the transmission of P. phippsi is realized in marine coastal ecosystems. Its' main intermediate host in the Arctic is the amphipod Gammarus (Lagunogammarus) setosus, commonin coastal. areas of the shelf zone throughout the Arctic basin. P. phippsi population in FJL and the entire European Arctic is on the whole maintained by a single obligate final host, the common eider Somateria mollissima. Prevalence (P) of P. phippsi in this bird reached 100 %, with the maximal infection intensity (IImax) of 1188 and the mean abundance (MA) of 492.1. Other species of birds found to be infected with P. phippsi (Arctic turn, black guillemot, purple sandpiper and several gulls) are facultative and/or eliminative hosts. The most heavily infected birds were Arctic terns (P = 72.7%, IImax = 227, MA = = 47.1), which contained single mature acanthocephalans. For one of the FJL regions, infections flows of P. phippsi through various host categories were calculated. Involvement of birds unrelated to the common eider into the circulation of P. phippsi is facilitated by their feeding character in the Arctic. While coastal crustaceans are abundant, fish food is relatively scarce (polar cod, snailfishes), and so amphipods make up a considerable part of the diet of marine birds in FJL, if not most of it, as for instance in case of Arctic tern. This promotes an easy entry of the larvae of crustaceans-parasitizing helminthes (cestodes and acanthocephalans, including cystacanths P. phippsi) into non-specific hosts and opens broad colonization possibilities

  15. [PATTERNS IN CIRCULATION AND TRANSMISSION OF MARINE BIRD PARASITES IN HIGH ARCTIC: A CASE OF ACANTHOCEPHALAN POLYMORPHUS PHIPPSI (PALAEACANTHOCEPHALA, POLYMORPHIDAE)].

    PubMed

    Galaktionov, K V; Atrashkevich, G I

    2015-01-01

    This study, based on the materials on parasitic infection of marine birds and invertebrates in Frantz Josef Land (FJL) collected in 1991-1993, focussed on the acanthocephalan Polymorphus phippsi. We identified this parasite, confirmed its species status and analysed its circulation and transmission patterns in high Arctic. The causes of its erroneous identification as P. minutus in several studies were also examined. In contrast to P. minutus, the transmission of P. phippsi is realized in marine coastal ecosystems. Its' main intermediate host in the Arctic is the amphipod Gammarus (Lagunogammarus) setosus, commonin coastal. areas of the shelf zone throughout the Arctic basin. P. phippsi population in FJL and the entire European Arctic is on the whole maintained by a single obligate final host, the common eider Somateria mollissima. Prevalence (P) of P. phippsi in this bird reached 100 %, with the maximal infection intensity (IImax) of 1188 and the mean abundance (MA) of 492.1. Other species of birds found to be infected with P. phippsi (Arctic turn, black guillemot, purple sandpiper and several gulls) are facultative and/or eliminative hosts. The most heavily infected birds were Arctic terns (P = 72.7%, IImax = 227, MA = = 47.1), which contained single mature acanthocephalans. For one of the FJL regions, infections flows of P. phippsi through various host categories were calculated. Involvement of birds unrelated to the common eider into the circulation of P. phippsi is facilitated by their feeding character in the Arctic. While coastal crustaceans are abundant, fish food is relatively scarce (polar cod, snailfishes), and so amphipods make up a considerable part of the diet of marine birds in FJL, if not most of it, as for instance in case of Arctic tern. This promotes an easy entry of the larvae of crustaceans-parasitizing helminthes (cestodes and acanthocephalans, including cystacanths P. phippsi) into non-specific hosts and opens broad colonization possibilities

  16. Topologically protected one-way edge mode in networks of acoustic resonators with circulating air flow

    NASA Astrophysics Data System (ADS)

    Ni, Xu; He, Cheng; Sun, Xiao-Chen; Liu, Xiao-ping; Lu, Ming-Hui; Feng, Liang; Chen, Yan-Feng

    2015-05-01

    Recent explorations of topology in physical systems have led to a new paradigm of condensed matters characterized by topologically protected states and phase transition, for example, topologically protected photonic crystals enabled by magneto-optical effects. However, in other wave systems such as acoustics, topological states cannot be simply reproduced due to the absence of similar magnetics-related sound-matter interactions in naturally available materials. Here, we propose an acoustic topological structure by creating an effective gauge magnetic field for sound using circularly flowing air in the designed acoustic ring resonators. The created gauge magnetic field breaks the time-reversal symmetry, and therefore topological properties can be designed to be nontrivial with non-zero Chern numbers and thus to enable a topological sonic crystal, in which the topologically protected acoustic edge-state transport is observed, featuring robust one-way propagation characteristics against a variety of topological defects and impurities. Our results open a new venue to non-magnetic topological structures and promise a unique approach to effective manipulation of acoustic interfacial transport at will.

  17. Synoptic patterns of atmospheric circulation associated with intense precipitation events over the Brazilian Amazon

    NASA Astrophysics Data System (ADS)

    Santos, Eliane Barbosa; Lucio, Paulo Sérgio; Santos e Silva, Cláudio Moisés

    2015-12-01

    The objective of this study is to characterize the atmospheric patterns associated with the occurrence of intense precipitation events (IPE) in different sub-regions of the Brazilian Amazon. Intense rainfall cases over six sub-regions were selected from a precipitation data set for the period from 1983 to 2012. The composition technique was used to characterize the prevailing atmospheric patterns for the occurrence of IPE. In the south of the Amazon, the composition fields showed a favorable configuration for the formation of the South Atlantic Convergence Zone (SACZ). Along the coast, the intense precipitation events must be associated with mesoscale systems, such as squall lines. In the northwest, they are apparently associated with the Intertropical Convergence Zone (ITCZ) and/or local convection. The results reveal the complexity of the synoptic environment associated with the formation and development of weather systems that produce heavy rainfall in the Amazon Basin. Several factors can interfere as conditions in large-scale, local conditions and thermodynamic factors.

  18. Parathyroid hormone secretory pattern, circulating activity, and effect on bone turnover in adult growth hormone deficiency.

    PubMed

    Ahmad, A M; Hopkins, M T; Fraser, W D; Ooi, C G; Durham, B H; Vora, J P

    2003-02-01

    Adult growth hormone deficiency (AGHD) is associated with osteoporosis. Reports have associated parathyroid hormone (PTH) circadian rhythm abnormalities with osteoporosis. Furthermore, there is evidence of relative PTH insensitivity in AGHD patients. Factors regulating PTH circadian rhythm are not fully understood. There is evidence that serum phosphate is a likely determinant of PTH rhythm. The aim of this study was to investigate PTH circadian rhythm and its circulating activity and association with bone turnover in untreated AGHD patients compared to healthy individuals. We sampled peripheral venous blood at 30-min and urine at 3-h intervals during the day over a 24-h period from 1400 h in 14 untreated AGHD patients (7 M, 7 W; mean age, 49.5 +/- 10.7 years) and 14 age (48.6 +/- 11.4 years; P = NS) and gender-matched controls. Cosinor analysis was performed to analyze rhythm parameters. Cross-correlational analysis was used to determine the relationship between variables. Serum PTH (1-84), phosphate, total calcium, urea, creatinine, albumin, type I collagen C-telopeptides (CT(x)), a bone resorption marker, and procollagen type I amino-terminal propeptide (PINP), a bone formation marker, were measured on all samples. Nephrogenous cyclic adenosine monophosphate (NcAMP), which reflects the renal activity of PTH, was calculated from plasma and urinary cAMP. Urinary calcium and phosphate were measured on all urine samples. Significant circadian rhythms were observed for serum PTH, phosphate, CT(x), and PINP in AGHD and healthy subjects (P < 0.001). No significant rhythm was observed for serum-adjusted calcium. PTH MESOR (rhythm-adjusted mean) was significantly higher (P < 0.05), whereas the MESOR values for phosphate, CT(x) (P < 0.05), and PINP (P < 0.001) were lower in AGHD patients than in controls. AGHD patients had significantly lower 24-h NcAMP (P < 0.001) and higher urinary calcium excretion (P < 0.05). Maximum cross-correlation between PTH and phosphate (r = 0

  19. Reorganization of the Hydrothermal Circulation Pattern at the Long Valley Exploratory Well, CA - Geologic Record and Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Fischer, M.; Hurter, S.; Stöckhert, B.

    2001-12-01

    The Long Valley Exploratory Well (LVEW), drilled into the resurgent dome at Long Valley Caldera (California) to explore the potential for geothermal power in an active magmatic system, recorded temperatures of only ca. 100° C at 2500 to 3000 m depth. This is well below the range expected above an active magma chamber. Open fissures encountered at 2600 m depth are coated by mm-sized idiomorphic quartz crystals with first and second order growth discontinuities. Specific growth defects indicating rapid crystallization reflect dramatic changes in SiO2 supersaturation. Fluid inclusions contain low salinity (0 to 5 wt-% NaCl equiv.) and low CO2 (<3 mole%) aqueous fluids, with V-L homogenization temperatures of 300 to 350° C, indicating trapping at more than 200° C above the ambient temperatures measured within the borehole today. The inhomogeneous quartz growth and fluid inclusion results reflect dramatic changes in the convective pattern of the hydrothermal system that led to the unexpected low temperatures at depth. Numerical simulations are being carried out to constrain the length and time scales relevant for the reorganization of the circulation pattern, in particular the influence of episodic heat supply by intrusions and changes of permeability related to seismic events.

  20. Expression patterns of chemokine receptors on circulating T cells from myelodysplastic syndrome patients.

    PubMed

    Sand, Kristoffer Evebø; Rye, Kristin Paulsen; Mannsåker, Bård; Bruserud, Oystein; Kittang, Astrid Olsnes

    2013-02-01

    Chemokines and their receptors are involved in the recruitment of leukocytes to sites of inflammation. Recently, chemokine expression signatures have been reported to convey a prognostic value in myelodysplastic syndrome (MDS) patients. In the present study, we investigated the chemokine receptor repertoire on fresh peripheral blood lymphocytes from 31 (22 low-risk and 9 high-risk) patients affected by MDS. Chemokine receptor expression was studied in defined T-cell subsets using eight-color flow cytometry. MDS patients exhibited quantitative differences in peripheral lymphocyte subpopulations. In addition, T cells obtained from MDS patients expressed a chemokine receptor pattern suggesting a dominance of mature and activated T cells. This is illustrated by increased levels of CCR3, CCR5, CX3CR1 and/or by a decreased abundance of CCR7 in defined T-cell subsets. The T-cell subset distribution appears to differ between the peripheral blood and the bone marrow of MDS patients, suggesting a preferential recruitment of specific T-cell subsets to the latter compartment. Alteration in chemokine receptor expression can develop over time even in patients that are considered clinically stable. Elevated expression levels of CXCR4 by CD8(+) cells were associated with prolonged patient survival and reduced numbers of bone marrow blasts. We conclude that immunological abnormalities in MDS also involve chemokine receptors on different subsets of T cells, and that these changes may have a prognostic value.

  1. Honeycomb superlattice pattern in a dielectric barrier discharge in argon/air

    SciTech Connect

    Zhu, Ping; Dong, Lifang Yang, Jing; Gao, Yenan; Wang, Yongjie; Li, Ben

    2015-02-15

    We report on a honeycomb superlattice pattern in a dielectric barrier discharge in argon/air for the first time. It consists of hexagon lattice and honeycomb framework and bifurcates from a hexagon pattern as the applied voltage increases. A phase diagram of the pattern as a function of the gas component and gas pressure is presented. The instantaneous images show that the hexagon lattice and honeycomb framework are ignited in turn in each half voltage cycle. The honeycomb framework is composed of filaments ignited randomly. The spatiotemporal dynamics of honeycomb superlattice pattern is discussed by wall charges.

  2. Recombination Pattern Reanalysis of Some HIV-1 Circulating Recombination Forms Suggest the Necessity and Difficulty of Revision

    PubMed Central

    Jia, Lei; Li, Lin; Li, Hanping; Liu, Siyang; Wang, Xiaolin; Bao, Zuoyi; Li, Tianyi; Zhuang, Daomin; Liu, Yongjian; Li, Jingyun

    2014-01-01

    Background Recombination is one of the major mechanisms underlying the generation of HIV-1 variability. Currently 61 circulating recombinant forms of HIV-1 have been identified. With the development of recombination detection techniques and accumulation of HIV-1 reference stains, more accurate mosaic structures of circulating recombinant forms (CRFs), like CRF04 and CRF06, have undergone repeated analysis and upgrades. Such revisions may also be necessary for other CRFs. Unlike previous studies, whose results are based primarily on a single recombination detection program, the current study was based on multiple recombination analysis, which may have produced more impartial results. Methods Representative references of 3 categories of intersubtype recombinants were selected, including BC recombinants (CRF07 and CRF08), BG recombinants (CRF23 and CRF24), and BF recombinants (CRF38 and CRF44). They were reanalyzed in detail using both the jumping profile hidden Markov model and RDP3. Results The results indicate that revisions and upgrades are very necessary and the entire re-analysis suggested 2 types of revision: (i) length of inserted fragments; and (ii) number of inserted fragments. The reanalysis also indicated that determination of small regions of about 200 bases or fewer should be performed with more caution. Conclusion Results indicated that the involvement of multiple recombination detection programs is very necessary. Additionally, results suggested two major challenges, one involving the difficulty of accurately determining the locations of breakpoints and the second involving identification of small regions of about 200 bases or fewer with greater caution. Both indicate the complexity of HIV-1 recombination. The resolution would depend critically on development of a recombination analysis algorithm, accumulation of HIV-1 stains, and a higher sequencing quality. With the changes in recombination pattern, phylogenetic relationships of some CRFs may also

  3. Numerical Study on the Impact of SST Initialization on Regional Circulation and Air Pollution at Southern Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Jeon, W.; Lee, H.; Lee, S.

    2010-12-01

    Numerical simulations were carried out to investigate the impact of temporal resolution of sea surface temperature on regional circulation and air pollution over southern Korean Peninsula. Well urbanized target area with densely populated inventories called Gwangyang bay is situated at the southern part of the Korean Peninsula, and assessment period is from 15 to 19 August 2007 for investigating the SST impact under various synoptic conditions. A three-dimensional non-hydrostatic atmospheric model RAMS and New Generation Sea Surface Temperature (NGSST) data was applied in this study. Two different numerical experiments were carried out in accordance with the temporal resolution of SST, which are, NGSST without temporal update (case NO-UP), and temporally varied NGSST for whole period (case YES-UP). Based on the Buoy observation, SST at Geoje Island near Gwayang bay region increased 4.1°C for target period. This rapid variation of SST cannot be negligible to estimate the meteorological wind field and the distribution of photochemical ozone emitted at the well urbanized Gwangyang bay. Wind intensity including wind direction is also influenced by the temporal variation of SST distribution. In case YES-UP with high temporal resolution of SST, Sea breeze is stronger and more reasonable than that estimated in any other cases due to the precise information of SST distribution. In IOA analysis, most successfully estimated IOA values for surface air temperature and wind speed arose in case YES-UP and their values reached on the 0.958 and 0.829, respectively. These differences were due to the discrepancy of the temperature gradient caused by different SST initialization. Diurnal variation of temperature and wind speed for YES_UP has indicated great agreement with the observation data and the statistics such as root mean squared error, index of agreement were also better than NO_UP. In order to assess the influence of the difference of the meteorological input data to air

  4. Urban air pollution patterns, land use, and thermal landscape: an examination of the linkage using GIS.

    PubMed

    Weng, Qihao; Yang, Shihong

    2006-06-01

    This article investigates the relationship of local air pollution pattern with urban land use and with urban thermal landscape using a GIS approach. Ambient air quality measurements for sulfur dioxide, nitrogen oxide, carbon monoxide, total suspended particles, and dust level were obtained for Guangzhou City in South China between 1981 and 2000. Landsat TM images and aerial photo derived maps were used to examine city's land use and land cover at different times and changes. Landsat thermal infrared data were employed to compute land surface temperatures and to assess urban thermal patterns. Relationships among the spatial patterns of air pollution, land use, and thermal landscape were sought through GIS and correlation analyses. Results show that the spatial patterns of air pollutants probed were positively correlated with urban built-up density, and with satellite derived land surface temperature values, particularly with measurements taken during the summer. It is suggested that further studies investigate the mechanisms of this linkage, and that remote sensing of air pollution delves into how the energy interacts with the atmosphere and the environment and how sensors see pollutants. Thermal infrared imagery could play a unique role in monitoring and modeling atmospheric pollution.

  5. Local and regional effects of large scale atmospheric circulation patterns on winter wind power output in Western Europe

    NASA Astrophysics Data System (ADS)

    Zubiate, Laura; McDermott, Frank; Sweeney, Conor; O'Malley, Mark

    2014-05-01

    Recent studies (Brayshaw, 2009, Garcia-Bustamante, 2010, Garcia-Bustamante, 2013) have drawn attention to the sensitivity of wind speed distributions and likely wind energy power output in Western Europe to changes in low-frequency, large scale atmospheric circulation patterns such as the North Atlantic Oscillation (NAO). Wind speed variations and directional shifts as a function of the NAO state can be larger or smaller depending on the North Atlantic region that is considered. Wind speeds in Ireland and the UK for example are approximately 20 % higher during NAO + phases, and up to 30 % lower during NAO - phases relative to the long-term (30 year) climatological means. By contrast, in southern Europe, wind speeds are 15 % lower than average during NAO + phases and 15 % higher than average during NAO - phases. Crucially however, some regions such as Brittany in N.W. France have been identified in which there is negligible variability in wind speeds as a function of the NAO phase, as observed in the ERA-Interim 0.5 degree gridded reanalysis database. However, the magnitude of these effects on wind conditions is temporally and spatially non-stationary. As described by Comas-Bru and McDermott (2013) for temperature and precipitation, such non-stationarity is caused by the influence of two other patterns, the East Atlantic pattern, (EA), and the Scandinavian pattern, (SCA), which modulate the position of the NAO dipole. This phenomenon has also implications for wind speeds and directions, which has been assessed using the ERA-Interim reanalysis dataset and the indices obtained from the PC analysis of sea level pressure over the Atlantic region. In order to study the implications for power production, the interaction of the NAO and the other teleconnection patterns with local topography was also analysed, as well as how these interactions ultimately translate into wind power output. The objective is to have a better defined relationship between wind speed and power

  6. Modeling the role of back-arc spreading in controlling 3-D circulation and temperature patterns in subduction zones

    NASA Astrophysics Data System (ADS)

    Kincaid, C.

    2005-12-01

    Subduction of oceanic lithosphere provides a dominant driving force for mantle dynamics and plate tectonics, and strongly modulates the thermal evolution of the mantle. Magma generation in arc environments is related to slab temperatures, slab dehydration/wedge hydration processes and circulation patterns in the mantle wedge. A series of laboratory experiments is used to model three-dimensional aspects of flow in subduction zones, and the consequent temperature variations in the slab and overlying mantle wedge. The experiments utilize a tank of glucose syrup to simulate the mantle and a Phenolic plate to represent subducting oceanic lithosphere. Different modes of plate sinking are produced using hydraulic pistons. The effects of longitudinal, rollback and slab-steepening components of slab motions are considered, along with different thicknesses of the over-riding lithosphere. Models look specifically at how distinct modes of back-arc spreading alter subduction zone temperatures and flow in the mantle wedge. Results show remarkably different temperature and circulation patterns when spreading is produced by rollback of the trench-slab-arc relative to a stationary overriding back-arc plate versus spreading due to motion of the overriding plate away from a fixed trench location. For rollback-induced spreading, flow trajectories in the wedge are shallow (e.g., limited upwelling), both the sub-arc and back-arc regions are supplied by material flowing around the receding slab. Flow lines in the sub-arc wedge are strongly trench-parallel. In these cases, strong lateral variations in slab surface temperature (SST) are recorded (hot at plate center, cool at plate edge). When the trench is fixed in space and spreading is produced by motion of the overriding plate, strong vertical flow velocities are recorded in the wedge, both the shallow sub-arc and back-arc regions are supplied by flow from under the overriding plate producing strong vertical shear. In these cases SSTs

  7. The analysis of in-air reverberation patterns from medical ultrasound transducers

    PubMed Central

    Quinn, T

    2014-01-01

    National guidelines for routine ultrasound quality assurance include the measurement of transducer sensitivity using the in-air reverberation pattern generated from a transducer operating in air. The in-air reverberation method has been compared with other well-known measures of transducer sensitivity, such as the Sonora FirstCall probe tester (Sonora Medical Systems Inc, Longmont, CO, USA) and phantom-based images. There is good agreement between the in-air reverberation images and the Sonora FirstCall probe data for individual crystal sensitivity. However, the in-air reverberation approach is cheaper and easier to implement for linear and curvilinear transducers. The methods used for measuring the in-air reverberation pattern and the influence of scanner parameters such as gain and output power have been investigated. In general, reliance on a visual assessment of reverberation depth can lead to inconsistencies in the measurement of reverberation depth, when taken over a period of several months. The value of scanner parameters, in particular scanner gain, is also important when trying to measure changes in reverberation depth due to changes in transducer performance. A more accurate assessment of changes in transducer sensitivity, using the in-air reverberation method, is found by measuring the peak pixel grey scale values within a chosen reverberation band in the image. This quantitative approach can be taken a step further by assessing changes within the whole in-air reverberation pattern, by applying a two-dimensional cross correlation between two reverberation images to assess changes in transducer performance. PMID:27433190

  8. Circulating CD14brightCD16+ ‘Intermediate’ Monocytes Exhibit Enhanced Parasite Pattern Recognition in Human Helminth Infection

    PubMed Central

    Meurs, Lynn; Mbow, Moustapha; Dièye, Tandakha Ndiaye; Mboup, Souleymane; Polman, Katja; Mountford, Adrian P.

    2014-01-01

    Circulating monocyte sub-sets have recently emerged as mediators of divergent immune functions during infectious disease but their role in helminth infection has not been investigated. In this study we evaluated whether ‘classical’ (CD14brightCD16−), ‘intermediate’ (CD14brightCD16+), and ‘non-classical’ (CD14dimCD16+) monocyte sub-sets from peripheral blood mononuclear cells varied in both abundance and ability to bind antigenic material amongst individuals living in a region of Northern Senegal which is co-endemic for Schistosoma mansoni and S. haematobium. Monocyte recognition of excretory/secretory (E/S) products released by skin-invasive cercariae, or eggs, of S. mansoni was assessed by flow cytometry and compared between S. mansoni mono-infected, S. mansoni and S. haematobium co-infected, and uninfected participants. Each of the three monocyte sub-sets in the different infection groups bound schistosome E/S material. However, ‘intermediate’ CD14brightCD16+ monocytes had a significantly enhanced ability to bind cercarial and egg E/S. Moreover, this elevation of ligand binding was particularly evident in co-infected participants. This is the first demonstration of modulated parasite pattern recognition in CD14brightCD16+ intermediate monocytes during helminth infection, which may have functional consequences for the ability of infected individuals to respond immunologically to infection. PMID:24762736

  9. [Genomic heterogeneity of hepatitis B virus, genotype A circulating in the metropolitan area of Buenos Aires, Argentina].

    PubMed

    Fernandez, C; Mariana; de Torres, R A

    1996-01-01

    HVB DNA was extracted from highly purified Dane particles, from sera of HBV viremic patients, collected in the metropolitan area of Buenos Aires (Argentina). HBV DNA was cloned in pUC18 vector, amplified in Escherichia coli DH5 F'. Plasmids were recovered and analyzed for HBV DNA inserts. Three recombinant plasmids, pHB4, pHB7 and pHB20 were selected, and HBVDNA inserts sequenced. The resulted sequences were incorporated at the GenBank, with the following accession numbers: PHB4P3=U33188; PHB4P5=U33189; PHB7P3=U33190; PHB7P5=U33191 and PHB20=U33190; PHB7P5=U33191 and PHB20=U33187. All belongs to the genotype A, pHB4 and pHB20 have a very close relation in between each other and with L13994 sequence, from North America origin. pHB7 have a significant distance from pHB4 and pHB20 and have a discrete homology with m57633 detected in Philippines. pHB4 shows a mutation at the T 3182-Leu in the preS1 region that change Pro for Leu, this mutation is absent in 125 sequences selected (having a 65% or more of homology) from NCBI by Blast algortm. The sequence of the pre C regions of all three inserts do not show any evidence to belong to the e-or scape mutants. Type A genotypes shows to be common in the area, but a hight degree of divergence have been demonstrate between two circulating strains. PMID:9335928

  10. [Genomic heterogeneity of hepatitis B virus, genotype A circulating in the metropolitan area of Buenos Aires, Argentina].

    PubMed

    Fernandez, C; Mariana; de Torres, R A

    1996-01-01

    HVB DNA was extracted from highly purified Dane particles, from sera of HBV viremic patients, collected in the metropolitan area of Buenos Aires (Argentina). HBV DNA was cloned in pUC18 vector, amplified in Escherichia coli DH5 F'. Plasmids were recovered and analyzed for HBV DNA inserts. Three recombinant plasmids, pHB4, pHB7 and pHB20 were selected, and HBVDNA inserts sequenced. The resulted sequences were incorporated at the GenBank, with the following accession numbers: PHB4P3=U33188; PHB4P5=U33189; PHB7P3=U33190; PHB7P5=U33191 and PHB20=U33190; PHB7P5=U33191 and PHB20=U33187. All belongs to the genotype A, pHB4 and pHB20 have a very close relation in between each other and with L13994 sequence, from North America origin. pHB7 have a significant distance from pHB4 and pHB20 and have a discrete homology with m57633 detected in Philippines. pHB4 shows a mutation at the T 3182-Leu in the preS1 region that change Pro for Leu, this mutation is absent in 125 sequences selected (having a 65% or more of homology) from NCBI by Blast algortm. The sequence of the pre C regions of all three inserts do not show any evidence to belong to the e-or scape mutants. Type A genotypes shows to be common in the area, but a hight degree of divergence have been demonstrate between two circulating strains.

  11. Assessment of the impact of the meteorological meso-scale circulation on air quality in arid subtropical region.

    PubMed

    Charabi, Yassine; Al-Bulooshi, Ali; Al-Yahyai, Sultan

    2013-03-01

    In this paper, COSMO numerical weather prediction model is used to simulate land-sea breeze circulation in the north coast of Oman and to analyze the variability of the PBL depth. Typical summer day 1st August 2009 and winter day 1st January 2009 were simulated and verified by surface observations. The COSMO model was initialized using the German global model which runs as 40 km resolution and 40 vertical layers. The simulations show differences in the onset, strength, and inland penetration of the sea breeze. The high sea-land thermal contrast in the summer season induces earlier onset and progression of the sea breeze with larger horizontal and vertical extents. The summer and winter inland penetration is simulated around 150 and 65 km, respectively. The PBL depth was defined from the verticals profiles of the turbulence kinetic energy (TKE). The simulated PBL height varied at 1,600 m in summer and 700 m in the winter case. These results are in general in good agreement with the simulations of the National Centers for Environmental Prediction Global Data Assimilation System (NCEP-GDAS) model. The dispersive ability of the atmosphere was tested through the vertical mixing coefficient (VMC) generated by NCEP-GDAS simulations. The VMC during the summer simulated case is approximately four times larger than the respective one during the winter case. Consequently, during the advection of winter sea breeze, a shallow dome less than 100 m is shaped and forms an obstacle to the air-pollutant dispersion.

  12. Present and future precipitation variability over the East African region using CORDEX simulations (COSMO-CLM) and its relation with circulation patterns

    NASA Astrophysics Data System (ADS)

    Souverijns, Niels; Thiery, Wim; Demuzere, Matthias; van Lipzig, Nicole

    2015-04-01

    The East African region is highly dependent on precipitation due to its water-fed agricultural system. On the other hand the region experiences a high interannual variability regarding precipitation amounts during several months. Consequently, there is a strong need to predict how precipitation variability will evolve under climate change in this region. This requires a good understanding of the processes that influence this variability. This study tackles this issue via the use of circulation patterns, shown to strongly influence precipitation over the East African region. Changes in (the frequency of) circulation patterns towards the future are therefore the main drivers of changes in precipitation variability. To investigate this issue a classification of the different circulation patterns over the region was executed for a reference period (1981-2010) on ERA Interim data using the COST733class software. Different algorithms are tested and their performance over the study area is evaluated. This results in a weather atlas concerning the circulation patterns and their corresponding precipitation amounts that are currently present over the region. Furthermore, the classification will be executed on the COSMO-CLM CORDEX-Africa evaluation simulation for the same reference period. The model results are evaluated by comparing them with the classification results of the ERA Interim data and observational datasets. To predict how precipitation variability changes towards the future, a classification is also applied on the whole CORDEX-Africa ensemble for a present (1981-2010) and future period (2071-2100) under RCP 8.5. Comparing both classifications makes it possible to detect differences in the frequencies of circulation patterns and in the circulation patterns themselves. Particular attention is paid to the months that show a high interannual variability in precipitation amounts, since changes here are of most importance for the region. Finally, the different drivers

  13. Spatial pattern of ozone injury in Aleppo pine related to air pollution dynamics in a coastal-mountain region of eastern Spain.

    PubMed

    Sanz, M J; Calatayud, V; Calvo, E

    2000-05-01

    In eastern Spain, studies combining the tracking and meso-scale circulations of air pollutants with the evaluation of their effects on plants have been undertaken since 1994. Meso-scale processes are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean area. The first results of these field surveys show that in 1994, 1995 and 1996, the distribution pattern of ozone visual injury (chlorotic mottle) in Pinus halepensis correlated with the penetration of pollutants transported by the sea-breeze into coastal valleys of Castellón (eastern Spain). In this tree species, longer needles are associated with higher chlorotic mottle, and ozone injury seems to be among the factors affecting needle retention and crown transparency.

  14. Chlorinated paraffins in indoor air and dust: concentrations, congener patterns, and human exposure.

    PubMed

    Fridén, Ulrika E; McLachlan, Michael S; Berger, Urs

    2011-10-01

    Chlorinated paraffins (CPs) are large production volume chemicals used in a wide variety of commercial applications. They are ubiquitous in the environment and humans. Human exposure via the indoor environment has, however, been barely investigated. In the present study 44 indoor air and six dust samples from apartments in Stockholm, Sweden, were analyzed for CPs, and indoor air concentrations are reported for the first time. The sumCP concentration (short chain CPs (SCCPs) and medium chain CPs (MCCPs)) in air ranged from <5-210 ng m(-3) as quantified by gas chromatography coupled to electron ionization tandem mass spectrometry (GC/EI-MS/MS). Congener group patterns were studied using GC with electron capture negative ionization MS (GC/ECNI-MS). The air samples were dominated by the more volatile SCCPs compared to MCCPs. SumCPs were quantified by GC/EI-MS/MS in the dust samples at low μg g(-1) levels, with a chromatographic pattern suggesting the prevalence of longer chain CPs compared to air. The median exposure to sumCPs via the indoor environment was estimated to be ~1 μg day(-1) for both adults and toddlers. Adult exposure was dominated by inhalation, while dust ingestion was suggested to be more important for toddlers. Comparing these results to literature data on dietary intake indicates that human exposure to CPs from the indoor environment is not negligible. PMID:21612825

  15. Experimental investigation on flame pattern formations of DME-air mixtures in a radial microchannel

    SciTech Connect

    Fan, Aiwu; Maruta, Kaoru; Nakamura, Hisashi; Kumar, Sudarshan; Liu, Wei

    2010-09-15

    Flame pattern formations of premixed DME-air mixture in a heated radial channel with a gap distance of 2.5 mm were experimentally investigated. The DME-air mixture was introduced into the radial channel through a delivery tube which connected with the center of the top disk. With an image-intensified high-speed video camera, rich flame pattern formations were identified in this configuration. Regime diagram of all these flame patterns was drawn based on the experimental findings in the equivalence ratio range of 0.6-2.0 and inlet velocity range of 1.0-5.0 m/s. Compared with our previous study on premixed methane-air flames, there are several distinct characteristics for the present study. First, Pelton-wheel-like rotary flames and traveling flames with kink-like structures were observed for the first time. Second, in most cases, flames can be stabilized near the inlet port of the channel, exhibiting a conical or cup-like shape, while the conventional circular flame was only observed under limited conditions. Thirdly, an oscillating flame phenomenon occurred under certain conditions. During the oscillation process, a target appearance was seen at some instance. These pattern formation characteristics are considered to be associated with the low-temperature oxidation of DME. (author)

  16. Hurricane-related air-sea interactions, circulation modifications, and coastal impacts on the eastern Louisiana coastline

    NASA Astrophysics Data System (ADS)

    Walker, N. D.; Pilley, C.; Li, C.; Liu, B.; Leben, R. R.; Raghunthan, V.; Ko, D.; Teague, W. J.

    2012-12-01

    Beginning in 1995, Atlantic hurricane activity increased significantly relative to the 1970s and 1980s. In 2005, records were broken when two hurricanes intensified rapidly to Category 5 for a period of time within the Gulf of Mexico, later landed, and flooded vast expanses of Louisiana's coastal regions within the span of 30 days. In this study, we investigate major hurricane events (including 2005) to elucidate air-sea interactions pertinent to hurricane intensity changes, shelf circulation, coastal flooding, and coastal land losses. We employ satellite measurements from passive sensors (temperature, true color, pigments) and active sensors (scatterometers, altimeters) in tandem with in-situ measurements from WAVCIS, NDBC, USGS, and NRL, as well as dedicated field campaigns along the coast. A selection of hurricane events during the 1998 to 2008 time period are used in this investigation. Research has shown that the Loop Current and its warm-core anticyclonic eddies (with high heat content) can intensify hurricanes transiting the Gulf; whereas, the cold-core cyclonic eddies (which are upwelling regions) can weaken hurricanes. Hurricane winds can intensify cold-core cyclonic eddies, which in some cases can impact outer shelf currents, mixing, and thermal structure throughout the water column. The exceptionally strong winds and waves in the northeast quadrant of these cyclonic atmospheric storms drive strong and long-lived westward currents. Storm surges and/or set-up of 2-6 m commonly occur along the Louisiana coastline, sometimes as a result of hurricanes traveling across the central Gulf of Mexico, at great distances from the coastal region experiencing the flooding (e.g. Hurricanes Rita and Gustav). The eastern shelf, north of the Mississippi River Birdfoot Delta, is particularly vulnerable to water level set-up and storm surge intensification due to the coastal orientation that causes the trapping of water. This area experienced land loss of 169 km2, or ~20

  17. Stress and physiological, behavioral and performance patterns of children under varied air ion levels

    NASA Astrophysics Data System (ADS)

    Fornof, K. T.; Gilbert, G. O.

    1988-12-01

    The possibility that individual differences in reactivity to stressors are a major factor underlying discordant results reported for air ion studies prompted an investigation of response patterns in school children under both normal indoor air ion levels and moderately increased negative air ion levels (4000±500/cm3). It was hypothesized that the impact of stressors is reduced with high negative air ionization, and that resultant changes in stress effects would be differentially exhibited according to the children's normal degree of stimulus reactivity. A counter-balanced, replicative, withinssubject design was selected, and the subjects were 12 environmentally sensitive, 1st 4th grade school children. In addition to monitoring stress effects on activity level, attention span, concentration to task and conceptual performance, measures were also made of urinary 5-hydroxyindole acetic acid levels and skin resistance response (SRR) to determine if changes extended to the physiological state. The cold water test was used to add physical stress and enable calculations of Lacey's autonomic lability scores (ALS) as indicators of individual reactivity. The results show main effects for air ions on both physiological parameters, with 48% less change in %SRR ( P<0.01) and 46% less change in urinary 5-HIAA levels ( P<0.055) during negative air ions, indicating increased stress tolerance. Strong interactive effects for ALS x air ion condition appeared, with high and low ALS children reacting oppositely to negative air ions in measures of skin resistance level ( P<0.01), wrist activity ( P<0.01) and digit span backwards ( P<0.004). Thus individual differences in autonomic reactivity and the presence or absence of stressors appear as critical elements for internal validity, and in preventing consequent skewed results from obscuring progress in air ion research.

  18. Patterns of entrapped air dissolution in a two-dimensional pilot-scale synthetic aquifer.

    PubMed

    McLeod, Heather C; Roy, James W; Smith, James E

    2015-01-01

    Past studies of entrapped air dissolution have focused on one-dimensional laboratory columns. Here the multidimensional nature of entrapped air dissolution was investigated using an indoor tank (180 × 240 × 600 cm(3) ) simulating an unconfined sand aquifer with horizontal flow. Time domain reflectometry (TDR) probes directly measured entrapped air contents, while dissolved gas conditions were monitored with total dissolved gas pressure (PTDG ) probes. Dissolution occurred as a diffuse wedge-shaped front from the inlet downgradient, with preferential dissolution at depth. This pattern was mainly attributed to increased gas solubility, as shown by PTDG measurements. However, compression of entrapped air at greater depths, captured by TDR and leading to lower quasi-saturated hydraulic conductivities and thus greater velocities, also played a small role. Linear propagation of the dissolution front downgradient was observed at each depth, with both TDR and PTDG , with increasing rates with depth (e.g, 4.1 to 5.7× slower at 15 cm vs. 165 cm depth). PTDG values revealed equilibrium with the entrapped gas initially, being higher at greater depth and fluctuating with the barometric pressure, before declining concurrently with entrapped air contents to the lower PTDG of the source water. The observed dissolution pattern has long-term implications for a wide variety of groundwater management issues, from recharge to contaminant transport and remediation strategies, due to the persistence of entrapped air near the water table (potential timescale of years). This study also demonstrated the utility of PTDG probes for simple in situ measurements to detect entrapped air and monitor its dissolution.

  19. Circulation factors affecting precipitation over Bulgaria

    NASA Astrophysics Data System (ADS)

    Nojarov, Peter

    2015-09-01

    The objective of this paper is to determine the influence of circulation factors on precipitation in Bulgaria. The study succeeds investigation on the influence of circulation factors on air temperatures in Bulgaria, as the focus here is directed toward precipitation amounts. Circulation factors are represented through two circulation indices, showing west-east or south-north transport of air masses over Bulgaria and four teleconnection indices (patterns)—North Atlantic Oscillation, East Atlantic, East Atlantic/Western Russia, and Scandinavian. Omega values at 700-hPa level show vertical motions in the atmosphere. Annual precipitation trends are mixed and not statistically significant. A significant decrease of precipitation in Bulgaria is observed in November due to the strengthening of the eastward transport of air masses (strengthening of EA teleconnection pattern) and anticyclonal weather (increase of descending motions in the atmosphere). There is also a precipitation decrease in May and June due to the growing influence of the Azores High. An increase of precipitation happens in September. All this leads to a redistribution of annual precipitation course, but annual precipitation amounts remain the same. However, this redistribution has a negative impact on agriculture and winter ski tourism. Zonal circulation has a larger influence on precipitation in Bulgaria compared to meridional. Eastward transport throughout the year leads to lower than the normal precipitation, and vice versa. With regard to the four teleconnection patterns, winter precipitation in Bulgaria is determined mainly by EA/WR teleconnection pattern, spring and autumn by EA teleconnection pattern, and summer by SCAND teleconnection pattern.

  20. On the North Atlantic circulation

    SciTech Connect

    Schmitz, W.J. Jr.; McCartney, M.S. )

    1993-02-01

    A summary for North Atlantic circulation is proposed to replace the circulation scheme hypothesized by Worthington in 1976. Divergences from the previous model are in thermohaline circulation, cross-equatorical transport and Florida Current sources, flow in the eastern Atlantic, circulation in the Newfoundland Basin, slope water currents, and flow pattern near the Bahamas. The circulation patterns presented here are consistent with the majority of of published accounts of flow components. 77 refs., 14 figs., 3 tabs.

  1. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  2. A method for the determination of potentially profitable service patterns for commuter air carriers

    NASA Technical Reports Server (NTRS)

    Ransone, R. K.; Kuhlthau, A. R.; Deptula, D. A.

    1975-01-01

    A methodology for estimating market conception was developed as a part of the short-haul air transportation program. It is based upon an analysis of actual documents which provide a record of known travel history. Applying this methodology a forecast was made of the demand for an air feeder service between Charlottesville, Virginia and Dulles International Airport. Local business travel vouchers and local travel agent records were selected to provide the documentation. The market was determined to be profitable for an 8-passenger Cessna 402B aircraft flying a 2-hour daily service pattern designed to mesh to the best extent possible with the connecting schedules at Dulles. The Charlottesville - Dulles air feeder service market conception forecast and its methodology are documented.

  3. 20th century trends of drought conditions in the Mediterranean: the influence of large-scale circulation patterns.

    NASA Astrophysics Data System (ADS)

    Sousa, Pedro; Trigo, Ricardo; Garcia-Herrera, Ricardo

    2010-05-01

    Here we have used the Self Calibrated PDSI (scPDSI) proposed by Wells et al (2004) as a more appropriate approach to characterize drought conditions in the Mediterranean area. The scPDSI has been shown to perform better (than the original PDSI) when evaluating spatial and temporal drought characteristics for regions outside the USA (Schrier et al, 2005). Seasonal and annual trends for the 1901-2000, 1901-1950 and 1951-2000 periods were computed using the standard Mann-Kendall test for trend significance evaluation. However, statistical significance obtained with this test can be highly misleading because it does not take into account the low variability nature that dominates the seasonal evolution of scPDSI fields. We have now improved these results by employing a modified Mann-Kendall test for auto-correlated series (Hamed and Ramachandra, 1997), such as the scPDSI case. This development allowed for a better definition of the Mediterranean areas characterized by significant changes in the scPDSI, namely the largely negative trends that dominate the Mediterranean basin, with the exceptions of parts of eastern Turkey and northwestern Iberia, since initially these areas were overestimated. The spatio-temporal variability of these indices was evaluated with an EOF analysis, in order to reduce the large dimensionality of the fields under analysis. Spatial representation of the first EOF patterns shows that EOF 1 covers the entire Mediterranean basin (16.4% of EV), while EOF2 is dominated by a W-E dipole (10% EV). The following EOF patterns present smaller scale features, and explain smaller amounts of variance. The EOF patterns have also facilitated the definition of four sub-regions with large socio-economic relevance: 1) Iberia, 2) Italian Peninsula, 3) Balkans and 4) Turkey. Afterwards we perform a comprehensive analysis on the links between the scPDSI and the large-scale atmospheric circulation indices that affect the Mediterranean basin, namely; NAO, EA, and SCAND

  4. On Temporal Patterns and Circulation of Influenza Virus Strains in Taiwan, 2008-2014: Implications of 2009 pH1N1 Pandemic

    PubMed Central

    Hsieh, Ying-Hen; Huang, Hsiang-Min; Lan, Yu-Ching

    2016-01-01

    Background It has been observed that, historically, strains of pandemic influenza led to succeeding seasonal waves, albeit with decidedly different patterns. Recent studies suggest that the 2009 A(H1N1)pdm09 pandemic has had an impact on the circulation patterns of seasonal influenza strains in the post-pandemic years. In this work we aim to investigate this issue and also to compare the relative transmissibility of these waves of differing strains using Taiwan influenza surveillance data before, during and after the pandemic. Methods We make use of the Taiwan Center for Disease Control and Prevention influenza surveillance data on laboratory-confirmed subtyping of samples and a mathematical model to determine the waves of circulating (and co-circulating) H1, H3 and B virus strains in Taiwan during 2008–2014; or namely, short before, during and after the 2009 pandemic. We further pinpoint the turning points and relative transmissibility of each wave, in order to ascertain whether any temporal pattern exists. Results/Findings For two consecutive years following the 2009 pandemic, A(H1N1)pdm09 circulated in Taiwan (as in most of Northern Hemisphere), sometimes co-circulating with AH3. From the evolution point of view, A(H1N1)pdm09 and AH3 were able to sustain their circulation patterns to the end of 2010. In fact, A(H1N1)pdm09 virus circulated in six separate waves in Taiwan between summer of 2009 and spring of 2014. Since 2009, a wave of A(H1N1)pmd09 occurred every fall/winter influenza season during our study period except 2011–2012 season, when mainly influenza strain B circulated. In comparing transmissibility, while the estimated per capita weekly growth rates for cumulative case numbers (and the reproduction number) seem to be lower for most of the influenza B waves (0.06~0.26; range of 95% CIs: 0.05~0.32) when compared to those of influenza A, the wave of influenza B from week 8 to week 38 of 2010 immediately following the fall/winter wave of 2009 A(H1N1

  5. The Relationship of Loss, Mean Age of Air and the Distribution of CFC's to Stratospheric Circulation and Implications for Atmospheric Lifetimes

    NASA Technical Reports Server (NTRS)

    Douglas, A. R.; Stolarski, R. S.; Schoeberl, M. R.; Jackman, C. H.; Gupta, M. L.; Newman, P. A.; Nielsen, J. E.; Fleming, E. L.

    2008-01-01

    Model-derived estimates of the annually integrated destruction and lifetime for various ozone depleting substances (ODSs) depend on the simulated stratospheric transport and mixing in the global model used to produce the estimate. Observations in the middle and high latitude lower stratosphere show that the mean age of an air parcel (i.e., the time since its stratospheric entry) is related to the fractional release for the ODs (i.e., the amount of the ODS that has been destroyed relative to the amount at the time of stratospheric entry). We use back trajectory calculations to produce an age spectrum, and explain the relationship between the mean age and the fractional release by showing that older elements in the age spectrum have experienced higher altitudes and greater ODs destruction than younger elements. In our study, models with faster circulations produce distributions for the age-of-air that are 'young' compared to a distribution derived from observations. These models also fail to reproduce the observed relationship between the mean age of air and the fractional release. Models with slower circulations produce both realistic distributions for mean age and a realistic relationship between mean age and fractional release. These models also produce a CFCl3 lifetime of approximately 56 years, longer than the 45 year lifetime used to project future mixing ratios. We find that the use of flux boundary conditions in assessment models would have several advantages, including consistency between ODS evolution and simulated loss even if the simulated residual circulation changes due to climate change.

  6. Hemispheric asymmetries and seasonality of mean age of air in the lower stratosphere: Deep versus shallow branch of the Brewer-Dobson circulation

    NASA Astrophysics Data System (ADS)

    Konopka, Paul; Ploeger, Felix; Tao, Mengchu; Birner, Thomas; Riese, Martin

    2015-03-01

    Based on multiannual simulations with the Chemical Lagrangian Model of the Stratosphere, (CLaMS) driven by ECMWF ERA-Interim reanalysis, we discuss hemispheric asymmetries and the seasonality of the mean age of air (AoA) in the lower stratosphere. First, the planetary wave forcing of the Brewer-Dobson circulation is quantified in terms of Eliassen Palm flux divergence calculated by using the isentropic coordinate θ. While the forcing of the deep branch at θ = 1000 K (around 10 hPa) has a clear maximum in each hemisphere during the respective winter, the shallow branch of the Brewer-Dobson circulation, i.e., between 100 and 70 hPa (380 < θ < 420 K), shows almost opposite seasonality in both hemispheres with a pronounced minimum between June and September in the Southern Hemisphere. Second, we decompose the time-tendency of AoA into the contributions of the residual circulation and of eddy mixing by analyzing the zonally averaged tracer continuity equation. In the tropical lower stratosphere between ±30°, the air becomes younger during boreal winter and older during boreal summer. During boreal winter, the decrease of AoA due to tropical upwelling outweighs aging by isentropic mixing. In contrast, weaker isentropic mixing outweighs an even weaker upwelling in boreal summer and fall making the air older during these seasons. Poleward of 60°, the deep branch locally increases AoA and eddy mixing locally decreases AoA with the strongest net decrease during spring. Eddy mixing in the Northern Hemisphere outweighs that in the Southern Hemisphere throughout the year.

  7. Exploratory Analysis of Spatial-Temporal Patterns of Air Pollution in the City

    NASA Astrophysics Data System (ADS)

    Champendal, Alexandre; Kanevski, Mikhail; Huguenot, Pierre-Emmanuel; Golay, Jean

    2013-04-01

    Air pollution in the city is an important problem influencing environment, well-being of society, economy, management of urban zones, etc. The problem is extremely difficult due to a very complex distribution of the pollution sources, morphology of the city and dispersion processes leading to multivariate nature of the phenomena and high local spatial-temporal variability. The task of understanding, modelling and prediction of spatial-temporal patterns of air pollution in urban zones is an interesting and challenging topic having many research axes from science-based modelling to geostatistics and data mining. The present research mainly deals with a comprehensive exploratory analysis of spatial-temporal air pollution data using statistical, geostatistical and machine learning tools. This analysis helps to 1) understand and model spatial-temporal correlations using variography, 2) explore the temporal evolution of spatial correlation matrix; 3) analyse and visualize an interconnection between measurement stations using network science tools; 4) quantify the availability and predictability of structured patterns. The real data case study deals with spatial-temporal air pollution data of canton Geneva (2002-2011). Carbon dioxide (NO2) have caught our attention. It has effects on health: nitrogen dioxide can irritate the lungs, effects on plants; NO2 contributes to the phenomenon of acid rain. The negative effects of nitrogen dioxides on plants are reducing the growth, production and pesticide resistance. And finally the effects on materials: nitrogen dioxides increase the corrosion. Well-defined patterns of spatial-temporal correlations were detected. The analysis and visualization of spatial correlation matrix for 91 stations were carried out using the network science tools and high levels of clustering were revealed. Moving Window Correlation Matrix and Spatio-temporal variography methods were applied to define and explore the dynamic of our data. More than just

  8. Experimental determination of the effect of mountain-valley breeze circulation on air pollution in the vicinity of Freiburg

    NASA Astrophysics Data System (ADS)

    Baumbach, Günter; Vogt, Ulrich

    Tethersonde and airship measurements were carried out in 1994 during two different seasons within the framework of the preparation of the Clean Air Plan of Freiburg. These investigations concerned the influence of the Freiburg mountain-valley wind system, the so-called Höllentäler, on Freiburg's air quality. Vertical and horizontal measurements carried out east of Freiburg in the Dreisam Valley revealed that when the mountain-valley wind system has developed during summer high-pressure weather conditions, Freiburg is supplied with low polluted air masses from the Black Forest at night up to the early morning hours. Conversely, it may occur that during stable weather conditions with low wind speeds, the polluted air masses which flow into the Black Forest during the day are transported back to Freiburg with the mountain wind, so that there is no fresh air supply.

  9. Patterns of cold-air drainage and microclimate in mid-latitude versus high-latitude mountains: contrasts and implications for climate change (Invited)

    NASA Astrophysics Data System (ADS)

    Pepin, N. C.

    2009-12-01

    Predictions of current spatial patterns of climate are difficult in areas of complex relief in all parts of the world, because of the interweaving influences of topography, elevation and aspect. These influences vary temporally as a result of the seasonal and diurnal cycles in radiation balance. In periods of negative energy balance, surface decoupling can occur as cold air drainage develops low-level temperature inversions, and the surface temperature regime beneath the inversion becomes divorced from free atmospheric forcing. Both the spatial scale and temporal persistence of this decoupling vary according to latitude, and although the physical processes that influence inversion formation are similar in polar areas and mid-latitude mountains, the contrasting seasonal and diurnal forcings make the end results very different. Examples are contrasted from detailed field temperature measurements (~50 sites per field area) taken over several years in areas of complex relief in the eastern Pyrenees (~42.5 deg N), the Oregon Cascades (also ~42.5 deg N) and Finnish Lapland (70 deg N and above the Arctic circle). In the former two locations decoupling is mostly diurnally driven, and small-scale topography is important in mediating the effects. Summer decoupling is brief and spatially limited, whereas winter decoupling can be more spatially extensive. There are strong relationships between synoptic conditions, as measured by objective flow indices at the 700 mb level (derived from NCEP/NCAR reanalysis fields) and the patterns of decoupling, which allow us to assess the effects of past and potential future circulation change on spatial patterns of future climate warming. In Finnish Lapland the decoupling regime most clearly approaches the mid-latitude pattern around the equinoxes when there are clear day and night periods. In winter and summer however (the polar night and polar day) with the muting of the diurnal cycle, processes are more poorly understood. Winter cold

  10. Capillary-driven self-assembly of microchips on oleophilic/oleophobic patterned surface using adhesive droplet in ambient air

    NASA Astrophysics Data System (ADS)

    Chang, Bo; Sariola, Veikko; Aura, Susanna; Ras, Robin H. A.; Klonner, Maria; Lipsanen, Harri; Zhou, Quan

    2011-07-01

    This letter describes a capillary-driven self-assembly technique using oleophilic/oleophobic patterned surface and adhesive in ambient air environment. We use a topographical microstructure of porous ormocer functionalized with a fluorinated trichlorosilane for the oleophobic area and gold patterns for the oleophilic area. The resulted oleophilic/oleophobic patterns show significant wettability contrast for adhesive (Delo 18507), with a contact angle of 119° on oleophobic part and 53° on the oleophilic part. Self-alignment of SU-8 microchips on the oleophilic/oleophobic patterns has been demonstrated. The results provide a promising solution for self-alignment of microparts using commercial adhesives in ambient air environment.

  11. Effects of synoptic-scale circulation pattern and local land surface condition on fog at Kushiro, northern Japan

    NASA Astrophysics Data System (ADS)

    Sugimoto, S.; Sato, T.; Nakamura, K.

    2012-12-01

    Marine stratiform clouds are frequently observed over western North Pacific offshore of the northeast Japan during summer when warm southerly wind prevails over underlying cold ocean current. Such clouds often migrate over Kushiro located in the coastal area of eastern Hokkaido Island, north Japan and are recognized as sea fog. On the other hand, Kushiro is a middle-sized city with population of over 180,000 and a large wetland expands at the north of Kushiro city. The difference of land surface condition between the city and the wetland might cause heterogeneity of the sea fog distribution over land, via dissipation and regeneration process of fog. In this study, long-term visibility data for Kushiro are investigated to clarify the relationship between interannual variation of fog frequency (FF) and large-scale circulation patterns. Furthermore, frequency of fog/low-level cloud (LC) is identified using satellite images and sensitivity experiments changing land surface condition are conducted using meteorological regional model to understand an impact of land use on the local fog distribution and its physical processes. Monthly mean FF trends observed at Kushiro during 1931 to 2010 shows significant decline (-3.3 day per decade). Since late 1970s, the decline at Kushiro has been particularly remarkable in July and August in association with an increased number of years with very low FF. Analysis of radiosonde data has revealed the development of shallow moist layer under a strong inversion layer during fog occurrence because of abundant moisture supply from southerly wind. However, cold and dry northerly wind prevents the formation of inversion layer during fog-free days. Composite analysis of reanalysis data suggests that the low-level southerly wind toward northeast Japan is weaker in the low FF month of July than climatology owing to a southward shift of the North Pacific High (NPH) and stronger Okhotsk High. In August, eastward displacement or shrinking of the

  12. Factors influencing time-location patterns and their impact on estimates of exposure: the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air).

    PubMed

    Spalt, Elizabeth W; Curl, Cynthia L; Allen, Ryan W; Cohen, Martin; Williams, Kayleen; Hirsch, Jana A; Adar, Sara D; Kaufman, Joel D

    2016-06-01

    We assessed time-location patterns and the role of individual- and residential-level characteristics on these patterns within the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) cohort and also investigated the impact of individual-level time-location patterns on individual-level estimates of exposure to outdoor air pollution. Reported time-location patterns varied significantly by demographic factors such as age, gender, race/ethnicity, income, education, and employment status. On average, Chinese participants reported spending significantly more time indoors and less time outdoors and in transit than White, Black, or Hispanic participants. Using a tiered linear regression approach, we predicted time indoors at home and total time indoors. Our model, developed using forward-selection procedures, explained 43% of the variability in time spent indoors at home, and incorporated demographic, health, lifestyle, and built environment factors. Time-weighted air pollution predictions calculated using recommended time indoors from USEPA overestimated exposures as compared with predictions made with MESA Air participant-specific information. These data fill an important gap in the literature by describing the impact of individual and residential characteristics on time-location patterns and by demonstrating the impact of population-specific data on exposure estimates.

  13. Flow patterns of natural convection in an air-filled vertical cavity

    NASA Astrophysics Data System (ADS)

    Wakitani, Shunichi

    1998-08-01

    Flow patterns of two-dimensional natural convection in a vertical air-filled tall cavity with differentially heated sidewalls are investigated. Numerical simulations based on a finite difference method are carried out for a wide range of Rayleigh numbers and aspect ratios from the onset of the steady multicellular flow, through the reverse transition to the unicellular pattern, to the unsteady multicellular flow. For aspect ratios (height/width) from 10 to 24, the various cellular structures characterized by the number of secondary cells are clarified from the simulations by means of gradually increasing Rayleigh number to 106. Unsteady multicellular solutions are found in some region of Rayleigh numbers less than those at which the reverse transition has occurred.

  14. Surface circulation patterns in the Sicily Channel and Ionian Sea as revealed by MODIS chlorophyll images from 2003 to 2007

    NASA Astrophysics Data System (ADS)

    Ciappa, Achille Carlo

    2009-09-01

    The surface circulation in the Sicily Channel and in the Ionian Sea is investigated using MODerate-resolution Infrared Spectro-radiometer (MODIS) chlorophyll-a images collected from 2003 to 2007. The use of chlorophyll as surface tracer in the area is verified by comparison with satellite altimeter measurements available during the same period. The interaction between waters with different concentrations of chlorophyll adds new particulars to the surface circulation of the Atlantic Water (AW) in the study area. In the Sicily Channel, warm anticyclonic structures located in the southern end drive the AW flow along their northern boundary to the south-east, towards the Libyan coast. In winter, the anticyclonic structures contract in a stable nucleus (the Sidra gyre) close to the African coast allowing AW intrusion over the Tunisian shelf (Atlantic Tunisian Current). In summer, the anticyclonic structure expands westwards, limiting the Atlantic Tunisian Current, and northwards, grazing the Atlantic Ionian Stream. It also fragments, allowing occasional AW intrusion into the central part of the Sicily Channel along different pathways. Due to the activity of the Sidra gyre, no evidence of the extension of the Atlantic Tunisian Current along the Libyan coast (east of 15°E) is found in the observation period. AW spreads into the central Ionian for long periods in summer but rarely in winter. It reaches the northern Ionian Sea via anticyclonic eddies (already observed in thermal imagery) departing from the northern and eastern border of the anticyclonic structure, captured by the prevalent clockwise offshore circulation in the northern Ionian (except in summer 2003). The deduced circulation is in agreement with recent studies based on the altimetric Mean Dynamic Topography and trajectories of drifters released in the Sicily Channel in recent years.

  15. Flaviviruses in Europe: Complex Circulation Patterns and Their Consequences for the Diagnosis and Control of West Nile Disease

    PubMed Central

    Beck, Cécile; Jimenez-Clavero, Miguel Angel; Leblond, Agnès; Durand, Benoît; Nowotny, Norbert; Leparc-Goffart, Isabelle; Zientara, Stéphan; Jourdain, Elsa; Lecollinet, Sylvie

    2013-01-01

    In Europe, many flaviviruses are endemic (West Nile, Usutu, tick-borne encephalitis viruses) or occasionally imported (dengue, yellow fever viruses). Due to the temporal and geographical co-circulation of flaviviruses in Europe, flavivirus differentiation by diagnostic tests is crucial in the adaptation of surveillance and control efforts. Serological diagnosis of flavivirus infections is complicated by the antigenic similarities among the Flavivirus genus. Indeed, most flavivirus antibodies are directed against the highly immunogenic envelope protein, which contains both flavivirus cross-reactive and virus-specific epitopes. Serological assay results should thus be interpreted with care and confirmed by comparative neutralization tests using a panel of viruses known to circulate in Europe. However, antibody cross-reactivity could be advantageous in efforts to control emerging flaviviruses because it ensures partial cross-protection. In contrast, it might also facilitate subsequent diseases, through a phenomenon called antibody-dependent enhancement mainly described for dengue virus infections. Here, we review the serological methods commonly used in WNV diagnosis and surveillance in Europe. By examining past and current epidemiological situations in different European countries, we present the challenges involved in interpreting flavivirus serological tests and setting up appropriate surveillance programs; we also address the consequences of flavivirus circulation and vaccination for host immunity. PMID:24225644

  16. Flaviviruses in Europe: complex circulation patterns and their consequences for the diagnosis and control of West Nile disease.

    PubMed

    Beck, Cécile; Jimenez-Clavero, Miguel Angel; Leblond, Agnès; Durand, Benoît; Nowotny, Norbert; Leparc-Goffart, Isabelle; Zientara, Stéphan; Jourdain, Elsa; Lecollinet, Sylvie

    2013-11-01

    In Europe, many flaviviruses are endemic (West Nile, Usutu, tick-borne encephalitis viruses) or occasionally imported (dengue, yellow fever viruses). Due to the temporal and geographical co-circulation of flaviviruses in Europe, flavivirus differentiation by diagnostic tests is crucial in the adaptation of surveillance and control efforts. Serological diagnosis of flavivirus infections is complicated by the antigenic similarities among the Flavivirus genus. Indeed, most flavivirus antibodies are directed against the highly immunogenic envelope protein, which contains both flavivirus cross-reactive and virus-specific epitopes. Serological assay results should thus be interpreted with care and confirmed by comparative neutralization tests using a panel of viruses known to circulate in Europe. However, antibody cross-reactivity could be advantageous in efforts to control emerging flaviviruses because it ensures partial cross-protection. In contrast, it might also facilitate subsequent diseases, through a phenomenon called antibody-dependent enhancement mainly described for dengue virus infections. Here, we review the serological methods commonly used in WNV diagnosis and surveillance in Europe. By examining past and current epidemiological situations in different European countries, we present the challenges involved in interpreting flavivirus serological tests and setting up appropriate surveillance programs; we also address the consequences of flavivirus circulation and vaccination for host immunity.

  17. Comparison of the efficacy of a forced-air warming system and circulating-water mattress on core temperature and post-anesthesia shivering in elderly patients undergoing total knee arthroplasty under spinal anesthesia

    PubMed Central

    Lee, Kyu Chang; Lee, Myeong Jong; Kim, Mi-Na; Kim, Ji-Sub; Lee, Won Sang; Lee, Jung Hwa

    2014-01-01

    Background In the present study, we compared changes in body temperature and the occurrence of shivering in elderly patients undergoing total knee arthroplasty under spinal anesthesia during warming with either a forced-air warming system or a circulating-water mattress. Methods Forty-six patients were randomly assigned to either the forced-air warming system (N = 23) or circulating-water mattress (N = 23) group. Core temperature was recorded using measurements at the tympanic membrane and rectum. In addition, the incidence and intensity of post-anesthesia shivering and verbal analogue score for thermal comfort were simultaneously assessed. Results Core temperature outcomes did not differ between the groups. The incidence (13.0 vs 43.5%, P < 0.05) and intensity (20/2/1/0/0 vs 13/5/3/2/0, P < 0.05) of post-anesthesia shivering was significantly lower in the forced-air system group than in the circulating-water mattress group. Conclusions The circulating-water mattress was as effective as the forced-air warming system for maintaining body temperature. However, the forced-air warming system was superior to the circulating-water mattress in reducing the incidence of post-anesthesia shivering. PMID:24910726

  18. Genesis of Bénard-Marangoni Patterns in Thin Liquid Films Drying into Air

    NASA Astrophysics Data System (ADS)

    Colinet, P.; Chauvet, F.; Dehaeck, S.

    Inspired by many years of motivating collaboration between the first author and Prof. Manuel G. Velarde, in the field of surface-tension-driven instabilities, pattern formation, and transition to turbulence, this paper presents recent experimental results obtained in collaboration with the second and third authors at the TIPs laboratory in Brussels. Namely, the evolution of Bénard-like patterns is explored for pure liquid layers evaporating into air, from chaotic regimes down to more stable structures with predominant hexagonal symmetry. Drying liquid layers indeed appear as a particularly simple example of system where, due to the decreasing liquid depth, the preferred wavelength of the pattern is continuously decreased in time, hence requiring perpetual creation of new convective cells. Such pattern "genesis" appears to lead to disordered structures with interesting characteristics, whose preliminary experimental investigation is carried out here. This paper is dedicated to Prof. Manuel G. Velarde, at the occasion of his 70th birthday, as a mark of deep gratitude for all positive scientific and cultural influences he had and he still has on many young scientists.

  19. Changes in Central European Soil Moisture Availability and Atmospheric Circulation Patterns between 1875 and 2005 - Regional Climate Change in Progress?

    NASA Astrophysics Data System (ADS)

    Trnka, M.; Kysely, J.; Dubrovsky, M.; Mozny, M.; Hostynek, J.; Svoboda, M.; Hayes, M. J.; Zalud, Z.

    2007-12-01

    Relationships between the soil moisture availability and the atmospheric circulation in Central Europe were analyzed for the period 1881-2005. The analysis was based on the Hess-Brezowsky catalogue of circulation types (CTs), and a series of weekly self-calibrated Palmer Z-index (scZ-index) and Palmer Drought Severity Index (scPDSI) values at seven stations where high-quality daily data has recently become available. The results show that the large-scale droughts during spring months (MAM) were associated with east (E), south (S), and south- east (SE) circulation types, whereas during summer (JJA) and the whole vegetation season, i.e., April-September (VEG), the Central Europe high pressure systems (HM) and east (E) circulation types were conducive to drought. Statistically significant drying trends were noted at a majority of the stations, especially during MAM and JJA, over the whole period for which the scPDSI and scZ-index series were available (1875-2005). Although almost no statistically significant tendencies were found prior to 1940, a significant tendency towards more intense drought was present at all sites after this year. The largest drying trend was noted during the VEG and AMJ seasons. The overall drying trend might be associated with shifts in the frequency of CTs, especially during AMJ. Although the aggregate frequency of occurrence of drought-conducive CTs (i.e. E, S and HM) remained stable at approximately 30% up to the 1940s, a steady increase to the present 55% frequency is observed afterwards. Higher frequencies of S and HM types drove the observed increase of drought-conducive CTs at the expense of N types that are associated with wet conditions. The long-term shifts in the frequency of circulation types conducive to drought explain more than 50% of the long-term variations of both scZ-index and PDSI values over the territory of the Czech Republic, and they are likely to affect whole central European region as well. Acknowledgement: This study

  20. DNS and measurements of scalar transfer across an air-water interface during inception and growth of Langmuir circulation

    NASA Astrophysics Data System (ADS)

    Hafsi, A.; Ma, Y.; Buckley, M.; Tejada-Martinez, A. E.; Veron, F.

    2016-05-01

    Direct numerical simulations (DNS) of an initially quiescent coupled air-water interface driven by an air flow with free stream speed of 5 m/s have been conducted and scalar transfer from the air side to the water side and subsequent vertical transport in the water column have been analysed. Two simulations are compared: one with a freely deforming interface, giving rise to gravity-capillary waves and aqueous Langmuir turbulence (LT) characterized by small-scale (centimeter-scale) Langmuir cells (LC), and the other with the interface intentionally held flat, i.e., without LC. It is concluded that LT serves to enhance vertical transport of the scalar in the water side and in the process increases scalar transfer efficiency from the air side to the water side relative to the shear-dominated turbulence in the flat interface case. Furthermore, transition to LT was observed to be accompanied by a spike in scalar flux characterized by an order of magnitude increase. These episodic flux increases, if linked to gusts and overall unsteadiness in the wind field, are expected to be an important contributor in determining the long-term average of the air-sea gas fluxes.

  1. Synoptic patterns and air mass transport during ozone episodes in northwestern Iberia.

    PubMed

    Saavedra, S; Rodríguez, A; Taboada, J J; Souto, J A; Casares, J J

    2012-12-15

    High levels of ozone are frequently measured at the Galicia (NW Iberian Peninsula) air quality monitoring stations from March to October. However, there have been very few studies on surface ozone in the northwestern Iberian Peninsula, most likely because the climate of this region is not favourable to photochemical ozone generation. The occurrence of these episodes may be related to either local-scale photochemical pollution or regional-scale transport from other polluted regions. In addition, high ozone episodes usually are developed under specific synoptic conditions. The main purposes of this study are to characterise the atmospheric conditions that lead to the ozone episodes in this region and to identify possible advection paths of ozone and precursors. A surface hourly ozone dataset (2002-2007) measured at rural sites in Galicia was analysed to identify high ozone episodes together with their associated synoptic patterns using a subjective classification with 23 different synoptic types. The synoptic weather patterns revealed that most of the episodes occur with high surface pressures centred over the British Isles and/or Central Europe while a high-altitude anticyclonic ridge crosses the Peninsula from North Africa, causing easterly or southeasterly winds. This analysis was completed with 3-day backward air mass trajectories obtained with HYSPLIT to assess the contribution of long-range transport, resulting in the following main routes: Mediterranean-Peninsular, South Atlantic-Portuguese, local and French-Cantabric.

  2. Monitoring intraurban spatial patterns of multiple combustion air pollutants in New York City: design and implementation.

    PubMed

    Matte, Thomas D; Ross, Zev; Kheirbek, Iyad; Eisl, Holger; Johnson, Sarah; Gorczynski, John E; Kass, Daniel; Markowitz, Steven; Pezeshki, Grant; Clougherty, Jane E

    2013-01-01

    Routine air monitoring provides data to assess urban scale temporal variation in pollution concentrations in relation to regulatory standards, but is not well suited to characterizing intraurban spatial variation in pollutant concentrations from local sources. To address these limitations and inform local control strategies, New York City developed a program to track spatial patterns of multiple air pollutants in each season of the year. Monitor locations include 150 distributed street-level sites chosen to represent a range of traffic, land-use and other characteristics. Integrated samples are collected at each distributed site for one 2-week session each season and in every 2-week period at five reference locations to track city-wide temporal variation. Pollutants sampled include PM(2.5) and constituents, nitrogen oxides, black carbon, ozone (summer only) and sulfur dioxide (winter only). During the first full year of monitoring more than 95% of designed samples were completed. Agreement between colocated samples was good (absolute mean % difference 3.2-8.9%). Street-level pollutant concentrations spanned a much greater range than did concentrations at regulatory monitors, especially for oxides of nitrogen and sulfur dioxide. Monitoring to characterize intraurban spatial gradients in ambient pollution usefully complements regulatory monitoring data to inform local air quality management. PMID:23321861

  3. Monitoring intraurban spatial patterns of multiple combustion air pollutants in New York City: design and implementation.

    PubMed

    Matte, Thomas D; Ross, Zev; Kheirbek, Iyad; Eisl, Holger; Johnson, Sarah; Gorczynski, John E; Kass, Daniel; Markowitz, Steven; Pezeshki, Grant; Clougherty, Jane E

    2013-01-01

    Routine air monitoring provides data to assess urban scale temporal variation in pollution concentrations in relation to regulatory standards, but is not well suited to characterizing intraurban spatial variation in pollutant concentrations from local sources. To address these limitations and inform local control strategies, New York City developed a program to track spatial patterns of multiple air pollutants in each season of the year. Monitor locations include 150 distributed street-level sites chosen to represent a range of traffic, land-use and other characteristics. Integrated samples are collected at each distributed site for one 2-week session each season and in every 2-week period at five reference locations to track city-wide temporal variation. Pollutants sampled include PM(2.5) and constituents, nitrogen oxides, black carbon, ozone (summer only) and sulfur dioxide (winter only). During the first full year of monitoring more than 95% of designed samples were completed. Agreement between colocated samples was good (absolute mean % difference 3.2-8.9%). Street-level pollutant concentrations spanned a much greater range than did concentrations at regulatory monitors, especially for oxides of nitrogen and sulfur dioxide. Monitoring to characterize intraurban spatial gradients in ambient pollution usefully complements regulatory monitoring data to inform local air quality management.

  4. Coastal ocean variability in the US Pacific Northwest region: seasonal patterns, winter circulation, and the influence of the 2009-2010 El Niño

    NASA Astrophysics Data System (ADS)

    Durski, Scott M.; Kurapov, Alexander L.; Allen, John S.; Kosro, P. Michael; Egbert, Gary D.; Shearman, R. Kipp; Barth, John A.

    2015-12-01

    A 2-km horizontal resolution ocean circulation model is developed for a large coastal region along the US Pacific Northwest (34-50N) to study how continental shelf, slope, and interior ocean variability influence each other. The model has been run for the time period September 2008-May 2011, driven by realistic surface momentum and heat fluxes obtained from an atmospheric model and lateral boundary conditions obtained from nesting in a global ocean model. The solution compares favorably to satellite measurements of sea surface temperature and sea surface height, observations of surface currents by high-frequency radars, mooring temperature time series, and glider temperature and salinity sections. The analysis is focused on the seasonal response of the coastal ocean with particular emphasis on the winter circulation patterns which have previously garnered relatively little attention. Interannual variability is examined through a comparison of the 2009-2010 winter influenced by El Niño and the winters in the preceding and following years. Strong northward winds combined with reduced surface cooling along the coast north of Cape Mendocino (40.4N) in winter 2009-2010, resulting in a vigorous downwelling season, characterized by relatively energetic northward currents and warmer ocean temperatures over the continental shelf and upper slope. An analysis of the time variability of the volume-averaged temperature and salinity in a coastal control volume (CV), that extends from 41 to 47N and offshore from the coast to the 200-m isobath, clearly shows relevant integrated characteristics of the annual cycle and the transitions between winter shelf circulation forced by northward winds and the summer circulation driven primarily by southward, upwelling-favorable winds. The analysis also reveals interesting interannual differences in these characteristics. In particular, the CV volume-average temperature remains notably warmer during January-March 2010 of the El Niño winter.

  5. Time-location patterns of a diverse population of older adults: the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air).

    PubMed

    Spalt, Elizabeth W; Curl, Cynthia L; Allen, Ryan W; Cohen, Martin; Adar, Sara D; Stukovsky, Karen H; Avol, Ed; Castro-Diehl, Cecilia; Nunn, Cathy; Mancera-Cuevas, Karen; Kaufman, Joel D

    2016-06-01

    The primary aim of this analysis was to present and describe questionnaire data characterizing time-location patterns of an older, multiethnic population from six American cities. We evaluated the consistency of results from repeated administration of this questionnaire and between this questionnaire and other questionnaires collected from participants of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air). Participants reported spending most of their time inside their homes (average: 121 h/week or 72%). More than 50% of the participants reported spending no time in several of the location options, including at home outdoors, at work/volunteer/school locations indoors or outdoors, or in "other" locations outdoors. We observed consistency between self-reported time-location patterns from repeated administration of the time-location questionnaire and compared with other survey instruments. Comparisons with national cohorts demonstrated the differences in time-location patterns in the MESA Air cohort due to differences in demographics, but the data showed similar trends in patterns by age, gender, season, and employment status. This study was the first to explicitly examine the time-location patterns in an older, multiethnic population and the first to add data on Chinese participants. These data can be used to inform future epidemiological research of MESA Air and other studies that include diverse populations.

  6. Elimination of young erythrocytes from blood circulation and altered erythropoietic patterns during paraquat induced anemic phase in mice.

    PubMed

    Bhardwaj, Nitin; Saxena, Rajiv K

    2014-01-01

    Paraquat a widely used herbicide causes a variety of toxic effects on humans and animals. The present study is focused on the interaction of paraquat with the mouse erythroid system. Administration of paraquat (10 mg/kg body weight i.p. on alternate days in C57Bl/6 mice) induced a significant fall in blood erythrocyte count on 7, 14, and 21 day time points but the erythrocyte count reverted back to normal by 28th day indicating the emergence of refractoriness to paraquat. A marked surge in the blood reticulocyte count was observed in paraquat treated mice that also subsided by 28th day. Young erythrocytes in circulation were randomly eliminated from blood circulation in paraquat treated mice and a significant elevation in the level of reactive oxygen species (ROS) was also observed maximally the erythrocytes of this age group. Cells representing various stages of erythroid differentiation in bone marrow and spleen were identified and enumerated flow cytometrically based on their expression of Ter119 and transferrin (CD71) receptor. Proliferative activity of erythroid cells, their relative proportion as well as their absolute numbers fell significantly in bone marrow of paraquat treated mice but all these parameters were significantly elevated in spleens of paraquat treated mice. These changes were essentially restricted to the cells belonging to the two earliest stages of erythroid differentiation. Taken together our results indicate that paraquat treatment causes a transient anemia in mice resulting from random elimination of young circulating erythrocytes as well as depressed erythropoietic activity in bone marrow. Spleen erythropoietic activity however was elevated in paraquat treated mice.

  7. The Breath of Planet Earth: Atmospheric Circulation. Assimilation of Surface Wind Observations

    NASA Technical Reports Server (NTRS)

    Atlas, Robert; Bloom, Stephen; Otterman, Joseph

    2000-01-01

    Differences in air pressure are a major cause of atmospheric circulation. Because heat excites the movement of atoms, warm temperatures cause, air molecules to expand. Because those molecules now occupy a larger space, the pressure that their weight exerts is decreased. Air from surrounding high-pressure areas is pushed toward the low-pressure areas, creating circulation. This process causes a major pattern of global atmosphere movement known as meridional circulation. In this form of convection, or vertical air movement, heated equatorial air rises and travels through the upper atmosphere toward higher latitudes. Air just above the equator heads toward the North Pole, and air just below the equator moves southward. This air movement fills the gap created where increased air pressure pushes down cold air. The ,cold air moves along the surface back toward the equator, replacing the air masses that rise there. Another influence on atmospheric. circulation is the Coriolis force. Because of the Earth's rotation, large-scale wind currents move in the direction of this axial spin around low-pressure areas. Wind rotates counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. just as the Earth's rotation affects airflow, so too does its surface. In the phenomenon of orographic lifting, elevated topographic features such as mountain ranges lift air as it moves up their surface.

  8. Horizontal coring using air as the circulating fluid: Some prototype studies conducted in G Tunnel at the Nevada Test Site for the Yucca Mountain Project

    SciTech Connect

    Chornack, M.P.; French, C.A.

    1989-12-31

    Horizontal coring using air as the circulating fluid has been conducted in the G Tunnel Underground Facility (GTUF) at the Nevada Test Site. This work is part of the prototype investigations of hydrogeology for the Yucca Mountain Project. The work is being conducted to develop methods and procedures that will be used at the Department of Energy`s Yucca Mountain Site, a candidate site for the nation`s first high-level nuclear waste repository, during the site characterization phase of the investigations. The United States Geological Survey (USGS) is conducting this prototype testing under the guidance of the Los Alamos National Laboratory (LANL) and in conjunction with Reynolds Electrical & Engineering Company (REECo), the drilling contractor. 7 refs., 8 figs., 5 tabs.

  9. A combination of air and fluid drilling technique for zones of lost circulation in the Black Warrior Basin

    SciTech Connect

    Graves, S.L.; Niederhofer, J.D.; Beavers, W.M.

    1986-02-01

    Structural geologic information available for the coal-bearing formations in the Black Warrior basin documents the occurrence of numerous fault and fracture zones. A combination air/fluid drilling technique may be advantageous to coalbed-methane operations in this and other areas with similar hydrologic and geologic conditions. The authors successfully used this technique recently on coalbed-methane wells in Tuscaloosa County, AL.

  10. Air pollution exposure affects circulating white blood cell counts in healthy subjects: the role of particle composition, oxidative potential and gaseous pollutants - the RAPTES project.

    PubMed

    Steenhof, Maaike; Janssen, Nicole A H; Strak, Maciej; Hoek, Gerard; Gosens, Ilse; Mudway, Ian S; Kelly, Frank J; Harrison, Roy M; Pieters, Raymond H H; Cassee, Flemming R; Brunekreef, Bert

    2014-02-01

    Studies have linked air pollution exposure to cardiovascular health effects, but it is not clear which components drive these effects. We examined the associations between air pollution exposure and circulating white blood cell (WBC) counts in humans. To investigate independent contributions of particulate matter (PM) characteristics, we exposed 31 healthy volunteers at five locations with high contrast and reduced correlations amongst pollutant components: two traffic sites, an underground train station, a farm and an urban background site. Each volunteer visited at least three sites and was exposed for 5 h with intermittent exercise. Exposure measurements on-site included PM mass and number concentration, oxidative potential (OP), elemental- and organic carbon, metals, O3 and NO2. Total and differential WBC counts were performed on blood collected before and 2 and 18 h post-exposure (PE). Changes in total WBC counts (2 and 18 h PE), number of neutrophils (2 h PE) and monocytes (18 h PE) were positively associated with PM characteristics that were high at the underground site. These time-dependent changes reflect an inflammatory response, but the characteristic driving this effect could not be isolated. Negative associations were observed for NO2 with lymphocytes and eosinophils. These associations were robust and did not change after adjustment for a large suite of PM characteristics, suggesting an independent effect of NO2. We conclude that short-term air pollution exposure at real-world locations can induce changes in WBC counts in healthy subjects. Future studies should indicate if air pollution exposure-induced changes in blood cell counts results in adverse cardiovascular effects in susceptible individuals.

  11. Characterising the hydrothermal circulation patterns beneath thermal springs in the limestones of the Carboniferous Dublin Basin, Ireland: a geophysical and geochemical approach.

    NASA Astrophysics Data System (ADS)

    Blake, Sarah; Henry, Tiernan; Muller, Mark R.; Jones, Alan G.; Moore, John Paul; Murray, John; Campanyà, Joan; Vozár, Jan; Walsh, John; Rath, Volker

    2016-04-01

    A hydrogeological conceptual model of the sources, circulation pathways and temporal variations of two low-enthalpy thermal springs is derived from a multi-disciplinary approach. The springs are situated in the Carboniferous limestones of the Dublin Basin, in east-central Ireland. Kilbrook spring (Co. Kildare) has the highest recorded temperatures for any thermal spring in Ireland (maximum of 25.0 °C), and St. Gorman's Well (Co. Meath) has a complex and variable temperature profile (maximum of 21.8 °C). These temperatures are elevated with respect to average Irish groundwater temperatures (9.5 - 10.5 °C), and represent a geothermal energy potential, which is currently under evaluation. A multi-disciplinary investigation based upon audio-magnetotelluric (AMT) surveys, time-lapse temperature and chemistry measurements, and hydrochemical analysis, has been undertaken with the aims of investigating the provenance of the thermal groundwater and characterising the geological structures facilitating groundwater circulation in the bedrock. The hydrochemical analysis indicates that the thermal waters flow within the limestones of the Dublin Basin, and there is evidence that Kilbrook spring receives a contribution from deep-basinal fluids. The time-lapse temperature, electrical conductivity and water level records for St. Gorman's Well indicate a strongly non-linear response to recharge inputs to the system, suggestive of fluid flow in karst conduits. The 3-D electrical resistivity models of the subsurface revealed two types of geological structure beneath the springs; (1) Carboniferous normal faults, and (2) Cenozoic strike-slip faults. These structures are dissolutionally enhanced, particularly where they intersect. The karstification of these structures, which extend to depths of at least 500 m, has provided conduits that facilitate the operation of a relatively deep hydrothermal circulation pattern (likely estimated depths between 240 and 1,000 m) within the Dublin

  12. Zoogeography of intertidal communities in the West Indian Ocean as determined by ocean circulation systems: patterns from the Tetraclita barnacles.

    PubMed

    Tsang, Ling Ming; Achituv, Yair; Chu, Ka Hou; Chan, Benny Kwok Kan

    2012-01-01

    The Indian Ocean is the least known ocean in the world with the biogeography of marine species in the West Indian Ocean (WIO) understudied. The hydrography of WIO is characterized by four distinct oceanographic systems and there were few glacial refugia formations in the WIO during the Pleistocene. We used the widely distributed intertidal barnacle Tetraclita to test the hypothesis that the distribution and connectivity of intertidal animals in the WIO are determined by the major oceanographic regime but less influenced by historical events such as Pleistocene glaciations. Tetraclita were studied from 32 locations in the WIO. The diversity and distribution of Tetraclita species in the Indian Ocean were examined based on morphological examination and sequence divergence of two mitochondrial genes (12S rDNA and COI) and one nuclear gene (histone 3, H3). Divergence in DNA sequences revealed the presence of seven evolutionarily significant units (ESUs) of Tetraclita in WIO, with most of them recognized as valid species. The distribution of these ESUs is closely tied to the major oceanographic circulation systems. T. rufotincta is distributed in the Monsoonal Gyre. T. ehsani is present in the Gulf of Oman and NW India. Tetraclita sp. nov. is associated with the Hydrochemical Front at 10°S latitude. T. reni is confined to southern Madagascan and Mauritian waters, influenced by the West Wind Drift. The endemic T. achituvi is restricted to the Red Sea. Tetraclita serrata consists of two ESUs (based on mtDNA analysis) along the east to west coast of South Africa. The two ESUs could not be distinguished from morphological analysis and nuclear H3 sequences. Our results support that intertidal species in the West Indian Ocean are associated with each of the major oceanographic circulation systems which determine gene flow. Geographical distribution is, however, less influenced by the geological history of the region. PMID:23024801

  13. Zoogeography of Intertidal Communities in the West Indian Ocean as Determined by Ocean Circulation Systems: Patterns from the Tetraclita Barnacles

    PubMed Central

    Tsang, Ling Ming; Achituv, Yair; Chu, Ka Hou; Chan, Benny Kwok Kan

    2012-01-01

    The Indian Ocean is the least known ocean in the world with the biogeography of marine species in the West Indian Ocean (WIO) understudied. The hydrography of WIO is characterized by four distinct oceanographic systems and there were few glacial refugia formations in the WIO during the Pleistocene. We used the widely distributed intertidal barnacle Tetraclita to test the hypothesis that the distribution and connectivity of intertidal animals in the WIO are determined by the major oceanographic regime but less influenced by historical events such as Pleistocene glaciations. Tetraclita were studied from 32 locations in the WIO. The diversity and distribution of Tetraclita species in the Indian Ocean were examined based on morphological examination and sequence divergence of two mitochondrial genes (12S rDNA and COI) and one nuclear gene (histone 3, H3). Divergence in DNA sequences revealed the presence of seven evolutionarily significant units (ESUs) of Tetraclita in WIO, with most of them recognized as valid species. The distribution of these ESUs is closely tied to the major oceanographic circulation systems. T. rufotincta is distributed in the Monsoonal Gyre. T. ehsani is present in the Gulf of Oman and NW India. Tetraclita sp. nov. is associated with the Hydrochemical Front at 10°S latitude. T. reni is confined to southern Madagascan and Mauritian waters, influenced by the West Wind Drift. The endemic T. achituvi is restricted to the Red Sea. Tetraclita serrata consists of two ESUs (based on mtDNA analysis) along the east to west coast of South Africa. The two ESUs could not be distinguished from morphological analysis and nuclear H3 sequences. Our results support that intertidal species in the West Indian Ocean are associated with each of the major oceanographic circulation systems which determine gene flow. Geographical distribution is, however, less influenced by the geological history of the region. PMID:23024801

  14. Zoogeography of intertidal communities in the West Indian Ocean as determined by ocean circulation systems: patterns from the Tetraclita barnacles.

    PubMed

    Tsang, Ling Ming; Achituv, Yair; Chu, Ka Hou; Chan, Benny Kwok Kan

    2012-01-01

    The Indian Ocean is the least known ocean in the world with the biogeography of marine species in the West Indian Ocean (WIO) understudied. The hydrography of WIO is characterized by four distinct oceanographic systems and there were few glacial refugia formations in the WIO during the Pleistocene. We used the widely distributed intertidal barnacle Tetraclita to test the hypothesis that the distribution and connectivity of intertidal animals in the WIO are determined by the major oceanographic regime but less influenced by historical events such as Pleistocene glaciations. Tetraclita were studied from 32 locations in the WIO. The diversity and distribution of Tetraclita species in the Indian Ocean were examined based on morphological examination and sequence divergence of two mitochondrial genes (12S rDNA and COI) and one nuclear gene (histone 3, H3). Divergence in DNA sequences revealed the presence of seven evolutionarily significant units (ESUs) of Tetraclita in WIO, with most of them recognized as valid species. The distribution of these ESUs is closely tied to the major oceanographic circulation systems. T. rufotincta is distributed in the Monsoonal Gyre. T. ehsani is present in the Gulf of Oman and NW India. Tetraclita sp. nov. is associated with the Hydrochemical Front at 10°S latitude. T. reni is confined to southern Madagascan and Mauritian waters, influenced by the West Wind Drift. The endemic T. achituvi is restricted to the Red Sea. Tetraclita serrata consists of two ESUs (based on mtDNA analysis) along the east to west coast of South Africa. The two ESUs could not be distinguished from morphological analysis and nuclear H3 sequences. Our results support that intertidal species in the West Indian Ocean are associated with each of the major oceanographic circulation systems which determine gene flow. Geographical distribution is, however, less influenced by the geological history of the region.

  15. Pattern recognition techniques for visualizing the biotropic waveform of air temperature and pressure

    NASA Astrophysics Data System (ADS)

    Ozheredov, V. A.

    2012-12-01

    It is known that long periods of adverse weather have a negative effect on the human cardiovascular system. A number of studies have set a lower limit of around 5 days for the duration of these periods. However, the specific features of the negative dynamics of the main weather characteristics—air temperature and atmospheric pressure—remained open. To address this problem, the present paper proposes a conjunctive method of the theory of pattern recognition. It is shown that this method approaches a globally optimal (in the sense of recognition errors) Neumann critical region and can be used to solve various problems in heliobiology. To illustrate the efficiency of this method, we show that some quickly relaxing short sequences of temperature and pressure time series (the so-called temperature waves and waves of atmospheric pressure changes) increase the risk of cardiovascular diseases and can lead to serious organic lesions (particularly myocardial infarction). It is established that the temperature waves and waves of atmospheric pressure changes increase the average morbidity rate of myocardial infarction by 90% and 110%, respectively. Atmospheric pressure turned out to be a more biotropic factor than air temperature.

  16. Numerical simulation of effective efficiency of a discrete multi V-pattern rib solar air channel

    NASA Astrophysics Data System (ADS)

    Kumar, Anil; Saini, R. P.; Saini, J. S.

    2016-10-01

    The use of artificial roughness in the form of repeated ribs has been found to be an efficient method of improving the heat transfer to fluid flowing in the channel. In this study, performance of solar air channel as a function of discrete multi V-pattern rib shapes has been investigated. The e/D was varied from 0.022 to 0.043, Gd/Lv was varied from 0.24 to 0.80, g/e was varied from 0.5 to 1.5, α was varied from 30° to 75°, P/e was varied from 6.0 to 12.0 and W/w was varied from 1.0 to 10.0. A methodology has been developed for the prediction of effective efficiency. Based on the values of effective efficiency, an optimization has been carried out to determine the set of data of roughness shapes parameters that correspond to better effective efficiency for given values of operating parameters of the air channel. Design plots have been represent to depict the data of individual roughness shapes parameters that characterize the optimum condition as a function of performance parameter and intensity of radiation. It was observed that the maximum values of effective efficiency for e/D of 0.043, Gd/Lv of 0.69, g/e of 1.0, α of 60°, P/e of 8.0 and W/w of 6.0. Discrete multi v-rib shape has been found to be better thermohydraulic performance (effective efficiency) as comparison to other rib shapes solar air channels.

  17. The impact of traffic-flow patterns on air quality in urban street canyons.

    PubMed

    Thaker, Prashant; Gokhale, Sharad

    2016-01-01

    We investigated the effect of different urban traffic-flow patterns on pollutant dispersion in different winds in a real asymmetric street canyon. Free-flow traffic causes more turbulence in the canyon facilitating more dispersion and a reduction in pedestrian level concentration. The comparison of with and without a vehicle-induced-turbulence revealed that when winds were perpendicular, the free-flow traffic reduced the concentration by 73% on the windward side with a minor increase of 17% on the leeward side, whereas for parallel winds, it reduced the concentration by 51% and 29%. The congested-flow traffic increased the concentrations on the leeward side by 47% when winds were perpendicular posing a higher risk to health, whereas reduced it by 17-42% for parallel winds. The urban air quality and public health can, therefore, be improved by improving the traffic-flow patterns in street canyons as vehicle-induced turbulence has been shown to contribute significantly to dispersion.

  18. The impact of traffic-flow patterns on air quality in urban street canyons.

    PubMed

    Thaker, Prashant; Gokhale, Sharad

    2016-01-01

    We investigated the effect of different urban traffic-flow patterns on pollutant dispersion in different winds in a real asymmetric street canyon. Free-flow traffic causes more turbulence in the canyon facilitating more dispersion and a reduction in pedestrian level concentration. The comparison of with and without a vehicle-induced-turbulence revealed that when winds were perpendicular, the free-flow traffic reduced the concentration by 73% on the windward side with a minor increase of 17% on the leeward side, whereas for parallel winds, it reduced the concentration by 51% and 29%. The congested-flow traffic increased the concentrations on the leeward side by 47% when winds were perpendicular posing a higher risk to health, whereas reduced it by 17-42% for parallel winds. The urban air quality and public health can, therefore, be improved by improving the traffic-flow patterns in street canyons as vehicle-induced turbulence has been shown to contribute significantly to dispersion. PMID:26412198

  19. Lead isotopes in North Pacific deep water - Implications for past changes in input sources and circulation patterns

    USGS Publications Warehouse

    van de Flierdt, T.; Frank, M.; Halliday, A.N.; Hein, J.R.; Hattendorf, B.; Gunther, D.; Kubik, P.W.

    2003-01-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10 Be/9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/204Pb from low values in the Miocene (??? 18.57) to high values at present day (??? 18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  20. Migration and circulation in Ecuador.

    PubMed

    Brea, J A

    1991-01-01

    "This study investigates labor mobility in Ecuador as a function of the socioeconomic structure of places and personal attributes of migrants and circulators (short-term movers).... Particular attention is given to the role of agrarian change in altering established migration and circulation patterns." The author finds that "circulation may significantly alter family organization and the role of women in many Ecuadorian communities."

  1. The Relationship of Loss, Mean Age of Air and the Distribution of CFCs to Stratospheric Circulation and Implications for Atmospheric Lifetimes

    NASA Technical Reports Server (NTRS)

    Douglass, A. R.; Stolarski, R. S.; Schoeberl, M. R.; Jackman, C. H.; Guptal, M. L.; Newman, P. A.; Nielsen, J. E.; Fleming, E. L.

    2007-01-01

    Man-made molecules called chlorofluorcarbons (CFCs) are broken apart in the stratosphere by high energy light, and the reactive chlorine gases that come from them cause the ozone hole. Since the ozone layer stops high energy light from reaching low altitudes, CFCs must be transported to high altitudes to be broken apart. The number of molecules per volume (the density) is much smaller at high altitudes than near the surface, and CFC molecules have a very small chance of reaching that altitude in any particular year. Many tons of CFCs were put into the atmosphere during the end of the last century, and it will take many years for all of them to be destroyed. Each CFC has an atmospheric lifetime that depends on the amount of energy required to break them apart. Two of the gases that were made the most are CFC13 and CF2C12. It takes more energy to break apart CF2C12 than CFC13, and its lifetime is about 100 years, nearly twice as long as the lifetime for CFC13. It is hard to figure out the lifetimes from surface measurements because we don't know exactly how much was released into the air each year. Atmospheric models are used to predict what will happen to ozone and other gases as the CFCs decrease and other gases like C02 continue to increase during the next century. CFC lifetimes are used to predict future concentrations and all assessment models use the predicted future concentrations. The models have different circulations and the amount of CFC lost according to the model may not match the loss that is expected according to the lifetime. In models the amount destroyed per year depends on how fast the model pushes air into the stratosphere and how much goes to high altitudes each year. This paper looks at the way the model circulation changes the lifetimes, and looks at measurements that tell us which model is more realistic. Some models do a good job reproducing the age-of-air, which tells us that these models are circulating the stratospheric air at the right

  2. Patterns of understory diversity in mixed coniferous forests of southern California impacted by air pollution.

    PubMed

    Allen, Edith B; Temple, Patrick J; Bytnerowicz, Andrzej; Arbaugh, Michael J; Sirulnik, Abby G; Rao, Leela E

    2007-01-01

    species in 2003. The easternmost site is also the driest and has the most sunlight filtering to the forest floor, possibly accounting for the higher species richness. The confounding effects of the precipitation gradient and possibly local disturbances do not show a simple correlation of air pollution with patterns of native and invasive species cover and richness. Nevertheless, the decline of native species and dominance by exotic species in the two westernmost polluted sites is cause for concern that air pollution is affecting the understory vegetation adversely.

  3. Seasonal variation of 228Ra/226Ra ratio in seaweed: implications for water circulation patterns in coastal areas of the Noto Peninsula, Japan.

    PubMed

    Inoue, M; Kofuji, H; Yamamoto, M; Komura, K

    2005-01-01

    To examine water circulation patterns of coastal water, 72 seaweed (Sargasso) samples and 27 coastal water samples were collected from coastal areas of the Noto Peninsula, Japan, during the period from December 1998 to June 2002. The (228)Ra and (226)Ra activities of those samples were measured by low-background gamma-ray spectrometry. There was a wide range of activities of (228)Ra (0.5-2Bq/kg-fresh) and (226)Ra (0.5-1.2Bq/kg-fresh) in the Sargasso samples. The (228)Ra/(226)Ra activity ratio of Sargasso samples exhibited seasonal variation with minimum values in June ((228)Ra/(226)Ra= approximately 1) and maximum values in December (1.5-2.5), which was mainly governed by changes in (228)Ra activity. It is also notable that the seasonal variation of the (228)Ra/(226)Ra ratio of Sargasso is in approximate agreement with that of the ambient coastal water. Sargasso samples appear to have retained the (228)Ra/(226)Ra ratio of the ambient coastal waters, and the temporal variations in that ratio provide insight into seasonal changes in water circulation in the Noto Peninsula coastal area.

  4. High-resolution records of Bonneville Basin paleohydrology offer new insights into changing atmospheric circulation patterns over North America from 26 ka through the Holocene

    NASA Astrophysics Data System (ADS)

    Steponaitis, E.; McGee, D.; Quade, J.; Andrews, A.; Edwards, R.; Hsieh, Y.; Broecker, W. S.; Cheng, H.

    2013-12-01

    The tremendous lateral extent of the Bonneville Basin, which covers much of western Utah, makes paleoclimate records from this region highly sensitive to global-scale changes in atmospheric circulation and hydrology. New paleoclimate records from speleothems and lacustrine carbonates offer insight into the hydrology the Bonneville Basin spanning from 26 ka through the Holocene. Anchored by high-precision U-Th dates, Sr records from crystalline lacustrine carbonates from throughout the basin provide a mechanism for constraining zonal variations in precipitation over time. To accomplish this, we exploit spatial variations in the 87Sr/86Sr ratios of fluvial inputs to Lake Bonneville (Hart et al. 2004). Paired with stable isotope records, these Sr records give a spatially detailed view of the response of Great Basin to global climate change, and by extension, insight into atmospheric circulation patterns over North America during abrupt climate changes. Stable isotope and trace metal records from Lehman Cave speleothems provide a high-resolution extension of these Great Basin hydrological records into the Holocene. Here we provide an overview of these unique paired records, focusing particular attention on the region's response to the Younger Dryas and Heinrich events 1 and 2. Hart, W.S. et al., The 87Sr/86Sr ratios of lacustrine carbonates and lake-level history of the Bonneville paleolake system. GSA Bulletin. 2004; 116: 1107-1119.

  5. An analysis of the high-latitude thermospheric wind pattern calculated by a thermospheric general circulation model. I - Momentum forcing

    NASA Technical Reports Server (NTRS)

    Killeen, T. L.; Roble, R. G.

    1984-01-01

    A diagnostic processor (DP) was developed for analysis of hydrodynamic and thermodynamic processes predicted by the NCAR thermospheric general circulation model (TGCM). The TGCM contains a history file on the projected wind, temperature and composition fields at each grid point for each hour of universal time. The DP assimilates the history file plus ion drag tensors and drift velocities, specific heats, coefficients of viscosity, and thermal conductivity and calculates the individual forcing terms for the momentum and energy equations for a given altitude. Sample momentum forcings were calculated for high latitudes in the presence of forcing by solar radiation and magnetospheric convection with a 60 kV cross-tail potential, i.e., conditions on Oct. 21, 1981. It was found that ion drag and pressure forces balance out at F region heights where ion drift velocities are small. The magnetic polar cap/auroral zone boundary featured the largest residual force or net acceleration. Diurnal oscillations were detected in the thermospheric convection, and geostrophic balance was dominant in the E layer.

  6. The Concentrations of Circulating Plasma Oxytocin and the Pattern of Oxytocin Release in Mare during Oestrus and after Ovulation

    NASA Astrophysics Data System (ADS)

    Bae, Sung Eun

    Mares susceptible to persistent mating-induced endometritis (PMIE) accumulate intrauterine fluid after mating. One of the factors causing delayed uterine clearance is thought to be impaired uterine contractility. Oxytocin is central in controlling myometrial contractility. The objective of the present study was to describe peripheral oxytocin release during estrus and in the early postovulatory period in reproductively-normal mares and to compare the baseline circulating oxytocin concentrations in reproductively-normal mares and mares with PMIE. Blood samples were collected from reproductively-normal mares (n=5) from day -5 of estrus to day 2 postovulation and every 5 min for 30 min from reproductively-normal mares (n=5) and mares with PMIE (n=5) on day 3 of estrus. Pulsatile secretion of oxytocin was observed in all mares. Mean plasma oxytocin concentrations were significantly higher (P<0.05) in estrus (day -5 to day -2) than on the day of ovulation (day 0). After ovulation, plasma oxytocin concentrations tended to increase. On day 3 of estrus, plasma oxytocin concentrations were significantly higher (P<0.01) in reproductively-normal mares than in mares with PMIE. The results showed there is a significant difference in plasma oxytocin concentrations between mares to PMIE. The low plasma oxytocin concentrations in mares with PMIE may contribute to predisposing factors in their poor uterine clearance in these mares.

  7. Plasma ghrelin in anorexia, bulimia, and binge-eating disorder: relations with eating patterns and circulating concentrations of cortisol and thyroid hormones.

    PubMed

    Troisi, Alfonso; Di Lorenzo, Giorgio; Lega, Ilaria; Tesauro, Manfredi; Bertoli, Aldo; Leo, Roberto; Iantorno, Micaela; Pecchioli, Chiara; Rizza, Stefano; Turriziani, Mario; Lauro, Renato; Siracusano, Alberto

    2005-01-01

    The present study was designed to investigate the relations between plasma ghrelin concentrations, eating patterns, and circulating concentrations of cortisol and thyroid hormones in women with anorexia nervosa, bulimia nervosa, and binge-eating disorder. The patterns of disordered eating behavior were assessed using the Eating Attitudes Test (EAT-26) and the Bulimia Test-Revised (BULIT-R). In women with eating disorders, but not in healthy control women, plasma ghrelin concentrations were negatively correlated with body mass index (BMI) and plasma concentrations of thyreotropin (TSH), free T3 and free T4, and positively correlated with plasma concentrations of cortisol. The ghrelin concentrations of women with binge-eating and purging behavior were significantly lower than those of women with anorexia nervosa, restricting type, and there was a negative relation between the frequency and severity of binge-eating and purging behavior, as measured by the BULIT-R total score, and ghrelin concentrations. In a multivariate regression model controlling for the confounding effects of body mass index (BMI) and age, higher ghrelin concentrations were correlated with lower BULIT-R total scores. The results of this study did not confirm the hypothesis advanced in previous studies that ghrelin concentrations are higher in patients with binge-eating/purging forms of eating disorders. Based on these data, we suggest that, in women with eating disorders, ghrelin concentrations best reflect nutritional status rather than specific patterns of disordered eating behavior.

  8. Cross-protective immunity can account for the alternating epidemic pattern of dengue virus serotypes circulating in Bangkok.

    PubMed

    Adams, B; Holmes, E C; Zhang, C; Mammen, M P; Nimmannitya, S; Kalayanarooj, S; Boots, M

    2006-09-19

    Dengue virus, the causative agent of dengue fever and its more serious manifestation dengue hemorrhagic fever, is widespread throughout tropical and subtropical regions. The virus exists as four distinct serotypes, all of which have cocirculated in Bangkok for several decades with epidemic outbreaks occurring every 8-10 years. We analyze time-series data of monthly infection incidence, revealing a distinctive pattern with epidemics of serotypes 1, 2, and 3 occurring at approximately the same time and an isolated epidemic of serotype 4 occurring in the intervening years. Phylogenetic analysis of virus samples collected over the same period shows that clade replacement events are linked to the epidemic cycle and indicates that there is an interserotypic immune reaction. Using an epidemic model with stochastic seasonal forcing showing 8- to 10-year epidemic oscillations, we demonstrate that moderate cross-protective immunity gives rise to persistent out-of-phase oscillations similar to those observed in the data, but that strong or weak cross-protection or cross-enhancement only produces in-phase patterns. This behavior suggests that the epidemic pattern observed in Bangkok is the result of cross-protective immunity and may be significantly altered by changes in the interserotypic immune reaction.

  9. Understanding hydrothermal circulation patterns at a low-enthalpy thermal spring using audio-magnetotelluric data: A case study from Ireland

    NASA Astrophysics Data System (ADS)

    Blake, Sarah; Henry, Tiernan; Muller, Mark R.; Jones, Alan G.; Moore, John Paul; Murray, John; Campanyà, Joan; Vozar, Jan; Walsh, John; Rath, Volker

    2016-09-01

    Kilbrook spring is a thermal spring in east-central Ireland. The temperatures in the spring are the highest recorded for any thermal spring in Ireland (maximum of 25 °C). The temperature is elevated with respect to average Irish groundwater temperatures (9.5-10.5 °C), and represents a geothermal energy potential, which is currently under evaluation. A multi-disciplinary investigation based upon an audio-magnetotelluric (AMT) survey, and hydrochemical analysis including time-lapse temperature and chemistry measurements, has been undertaken with the aims of investigating the provenance of the thermal groundwater and characterising the geological structures facilitating groundwater circulation in the bedrock. The three-dimensional (3-D) electrical resistivity model of the subsurface at Kilbrook spring was obtained by the inversion of AMT impedances and vertical magnetic transfer functions. The model is interpreted alongside high resolution temperature and electrical conductivity measurements, and a previous hydrochemical analysis. The hydrochemical analysis and time-lapse measurements suggest that the thermal waters have a relatively stable temperature and major ion hydrochemistry, and flow within the limestones of the Carboniferous Dublin Basin at all times. The 3-D resistivity model of the subsurface reveals a prominent NNW aligned structure within a highly resistive limestone lithology that is interpreted as a dissolutionally enhanced strike-slip fault, of Cenozoic age. The karstification of this structure, which extends to depths of at least 500 m directly beneath the spring, has provided conduits that facilitate the operation of a relatively deep hydrothermal circulation pattern (likely estimated depths between 560 and 1000 m) within the limestone succession of the Dublin Basin. The results of this study support the hypothesis that the winter thermal maximum and simultaneous increased discharge at Kilbrook spring is the result of rapid infiltration, heating and

  10. The vascular pattern and viability of microvascularized rib grafts based on periosteal circulation--an experimental study

    SciTech Connect

    Papanastasiou, V.W.; Lalonde, D.H.; Williams, H.B.

    1984-11-01

    Previous reports have stressed the importance of the nutrient blood supply in rib grafts transferred by microvascular anastomoses. In the present experimental study, we have demonstrated that a rib graft transferred by microvascular anastomoses based on periosteal vessels can survive; vascular clearing studies demonstrated that the vascularity of these grafts extends not only into the cortex but the medulla as well. The relative facility of harvesting these grafts (compared with those based on nutrient vessels) should make them the favored choice. Technetium bone scintigraphy proved accurate in the assessment of both vascular pattern and microanastomotic patency. Tetracycline labeling did not correlate well with the patency of a rib graft's pedicle blood supply.

  11. Upper Air Temperature and Circulation Climatologies from GPS Radio Occultation Measurements for Climate Process Studies and Model Evaluation

    NASA Astrophysics Data System (ADS)

    Ao, C. O.; Verkhoglyadova, O. P.; Mannucci, A. J.; Leroy, S. S.

    2014-12-01

    GPS radio occultation (RO) measurements are known to yield highly accurate temperature and geopotential height in the upper troposphere and lower stratosphere (UTLS) with 200 m vertical resolution in all-weather conditions. With over twelve years (2001-present) of continuous GPS RO measurements now available from CHAMP, COSMIC, and other missions, the dataset has become increasingly valuable in the study of upper air climate trend, variability, and processes. In this presentation, we will describe our approach towards the generation of global monthly gridded data products that include temperature, geopotential height, and geostrophic wind in the UTLS. To interpolate or map the irregularly sampled RO data into a 2D grid, a Bayesian method with spherical harmonic basis functions is implemented. Furthermore, we will quantify the measurement and sampling uncertainty associated with the monthly gridded data. Applications of the dataset in the variability of the tropical belt and CMIP5 model evaluation will be presented. In addition, we will discuss recent progress in reducing systematic retrieval errors as well as efforts to extend the current data record rigorously to the GPS/MET era (1995-1997).

  12. Intraoperative Core Temperature Patterns, Transfusion Requirement, and Hospital Duration in Patients Warmed with Forced Air

    PubMed Central

    Sun, Zhuo; Honar, Hooman; Sessler, Daniel I.; Dalton, Jarrod E.; Yang, Dongsheng; Panjasawatwong, Krit; Deroee, Armin F.; Salmasi, Vafi; Saager, Leif; Kurz, Andrea

    2015-01-01

    Background Core temperature patterns in patients warmed with forced-air remain poorly characterized. Also unknown is the extent to which transient and mild intraoperative hypothermia contributes to adverse outcomes in broad populations. Methods We evaluated esophageal (core) temperatures in 58,814 adults having surgery lasting >60 min who were warmed with forced air. Independent associations between hypothermic exposure and transfusion requirement and duration of hospitalization was evaluated. Results In every percentile subgroup, core temperature decreased during the first hour and subsequently increased. The mean lowest core temperature during the first hour was 35.7 ± 0.6°C. Sixty-four percent of the patients reached a core temperature threshold of <36°C 45 min after induction; 29% reached a core temperature threshold of <35.5°C. Nearly half the patients had continuous core temperatures <36°C for more than an hour, and 20% of the patients were <35.5°C for more than an hour. Twenty percent of patients had continuous core temperatures <36°C for more than 2 h, and 8% of the patients were below 35.5°C for more than 2 h. Hypothermia was independently associated with both transfusion and duration of hospitalization, although prolongation of hospitalization was small. Conclusions Even in actively warmed patients, hypothermia is routine in the first hour of anesthesia. Thereafter, average core temperatures progressively increase. Nonetheless, intraoperative hypothermia was common, and often prolonged. Hypothermia was associated with increased transfusion requirement which is consistent with numerous randomized trials. PMID:25603202

  13. Impact of cercal air currents on singing motor pattern generation in the cricket (Gryllus bimaculatus DeGeer).

    PubMed

    Jacob, Pedro F; Hedwig, Berthold

    2015-11-01

    The cercal system of crickets detects low-frequency air currents produced by approaching predators and self-generated air currents during singing, which may provide sensory feedback to the singing motor network. We analyzed the effect of cercal stimulation on singing motor pattern generation to reveal the response of a singing interneuron to predator-like signals and to elucidate the possible role of self-generated air currents during singing. In fictive singing males, we recorded an interneuron of the singing network while applying air currents to the cerci; additionally, we analyzed the effect of abolishing the cercal system in freely singing males. In fictively singing crickets, the effect of short air stimuli is either to terminate prematurely or to lengthen the interchirp interval, depending on their phase in the chirp cycle. Within our stimulation paradigm, air stimuli of different velocities and durations always elicited an inhibitory postsynaptic potential in the singing interneuron. Current injection in the singing interneuron elicited singing motor activity, even during the air current-evoked inhibitory input from the cercal pathway. The disruptive effects of air stimuli on the fictive singing pattern and the inhibitory response of the singing interneuron point toward the cercal system being involved in initiating avoidance responses in singing crickets, according to the established role of cerci in a predator escape pathway. After abolishing the activity of the cercal system, the timing of natural singing activity was not significantly altered. Our study provides no evidence that self-generated cercal sensory activity has a feedback function for singing motor pattern generation.

  14. Eastern Caribbean Circulation and Island Mass Effect on St. Croix, US Virgin Islands: A Mechanism for Relatively Consistent Recruitment Patterns.

    PubMed

    Chérubin, Laurent Marcel; Garavelli, Lysel

    2016-01-01

    The northeastern Caribbean Sea is under the seasonal influence of the Trade Winds but also of the Orinoco/Amazon freshwater plume. The latter is responsible for intensification of the Caribbean Current in general and of its eddy activity in the northern part of the Caribbean Sea. More importantly, we show in this study that the front of the freshwater plume drives a northward flow that impinges directly on the island of St. Croix in the United States Virgin Islands. The angle of incidence of the incoming flow controls the nature of the wake on both sides and ends of the island, which changes from cyclonic to anticylonic wake flow, with either attached or shed eddies. Using an off-line bio-physical model, we simulated the dispersal and recruitment of an abundant Caribbean coral reef fish, the bluehead wrasse (Thalassoma bifasciatum) in the context of the wake flow variability around St. Croix. Our results revealed the role played by the consistent seasonal forcing of the wake flow on the recruitment patterns around the island at the interannual scale. The interannual variability of the timing of arrival and northward penetration of the plume instead controls the nature of the wake, hence the regional spatial recruitment patterns. PMID:26942575

  15. Eastern Caribbean Circulation and Island Mass Effect on St. Croix, US Virgin Islands: A Mechanism for Relatively Consistent Recruitment Patterns

    PubMed Central

    Chérubin, Laurent Marcel; Garavelli, Lysel

    2016-01-01

    The northeastern Caribbean Sea is under the seasonal influence of the Trade Winds but also of the Orinoco/Amazon freshwater plume. The latter is responsible for intensification of the Caribbean Current in general and of its eddy activity in the northern part of the Caribbean Sea. More importantly, we show in this study that the front of the freshwater plume drives a northward flow that impinges directly on the island of St. Croix in the United States Virgin Islands. The angle of incidence of the incoming flow controls the nature of the wake on both sides and ends of the island, which changes from cyclonic to anticylonic wake flow, with either attached or shed eddies. Using an off-line bio-physical model, we simulated the dispersal and recruitment of an abundant Caribbean coral reef fish, the bluehead wrasse (Thalassoma bifasciatum) in the context of the wake flow variability around St. Croix. Our results revealed the role played by the consistent seasonal forcing of the wake flow on the recruitment patterns around the island at the interannual scale. The interannual variability of the timing of arrival and northward penetration of the plume instead controls the nature of the wake, hence the regional spatial recruitment patterns. PMID:26942575

  16. Eastern Caribbean Circulation and Island Mass Effect on St. Croix, US Virgin Islands: A Mechanism for Relatively Consistent Recruitment Patterns.

    PubMed

    Chérubin, Laurent Marcel; Garavelli, Lysel

    2016-01-01

    The northeastern Caribbean Sea is under the seasonal influence of the Trade Winds but also of the Orinoco/Amazon freshwater plume. The latter is responsible for intensification of the Caribbean Current in general and of its eddy activity in the northern part of the Caribbean Sea. More importantly, we show in this study that the front of the freshwater plume drives a northward flow that impinges directly on the island of St. Croix in the United States Virgin Islands. The angle of incidence of the incoming flow controls the nature of the wake on both sides and ends of the island, which changes from cyclonic to anticylonic wake flow, with either attached or shed eddies. Using an off-line bio-physical model, we simulated the dispersal and recruitment of an abundant Caribbean coral reef fish, the bluehead wrasse (Thalassoma bifasciatum) in the context of the wake flow variability around St. Croix. Our results revealed the role played by the consistent seasonal forcing of the wake flow on the recruitment patterns around the island at the interannual scale. The interannual variability of the timing of arrival and northward penetration of the plume instead controls the nature of the wake, hence the regional spatial recruitment patterns.

  17. Circulation patterns related to debris-flow triggering in the Zermatt valley in current and future climates

    NASA Astrophysics Data System (ADS)

    van den Heuvel, Floor; Goyette, Stéphane; Rahman, Kazi; Stoffel, Markus

    2016-11-01

    The principal objective of this study was to investigate the types of large-scale meteorological situations that are conducive to the precipitation and temperature conditions most likely to trigger debris flows in the Zermatt valley, Switzerland, under current and future climates. A two-dimensional Bayesian probability calculation was applied to take account of uncertainties in debris-flow triggering. Precipitation quantities exceeding the 95th percentile of daily precipitation amounts were found to have a significantly higher probability to coincide with observed debris flows. A different relationship exists for extreme temperatures, however. Southerly air flows, weak horizontal pressure gradients over Europe, and westerly flows are mostly associated with observed debris flows and 95th precipitation percentile exceedances. These principal flow directions are well represented in the regional climate model (RCM) HIRHAM control simulations for events exceeding the 95th precipitation percentile and the 30th temperature percentile. Under the IPCC A2 emission scenario, westerly and southerly flows are mostly responsible for these precipitation and temperature conditions under the hypothesis of slow adaptation to climate change (HS1/HC1). Under the hypothesis of rapid adaptation to climate change (HS1/HS1), southerly flows and weak horizontal pressure gradients are likely to gain in importance. In both scenarios for the future, southeasterly flows are among the principal flow directions responsible for the joint exceedance of the 95th precipitation percentile and the 30th temperature percentile, while these were absent in observations and the control simulation.

  18. Long-term trends of continental-scale PCB patterns studied using a global atmosphere-ocean general circulation model.

    PubMed

    Stemmler, Irene; Lammel, Gerhard

    2012-07-01

    Continental-scale distribution and inter-continental transport of four polychlorinated biphenyl (PCB) congeners (28, 101, 153, 180) from 1950 to 2010 were studied using the global multicompartment chemistry transport model MPI-MCTM. Following identical primary emissions for all PCB congeners into air, most of the burden is stored in terrestrial (soil and vegetation) compartments. Thereby, PCB-28, PCB-101 and PCB-153 show a shift of the soil burden maxima from source to remote regions. This shift is downwind with regard to the westerlies for Eurasia and upwind for North America and more prominent for the lighter PCBs than for PCB-153 or PCB-180. In meridional direction, all congeners' distributions underwent a northward migration in Eurasia and North America since the 1950s. Inter-continental transport from Eurasian sources accounts largely for contamination of Alaska and British Columbia and determines the migration of the PCB distribution in soil in North America. Trans-Pacific transport occurs mainly in the gas phase in boreal winter (December-January-February) at 3-4 km altitude and is on a multi-year time scale strongly linked to the atmospheric pressure systems over the Pacific. Inter-continental transport of the lighter, more volatile PCBs is more efficient than for the heavier PCBs.

  19. Interannual Variability and Trends in Daily Temperature and Precipitation Extreme Indices in Finland in Relation to Atmospheric Circulation Patterns, 1961-2011

    NASA Astrophysics Data System (ADS)

    Irannezhad, Masoud; Kløve, Bjørn

    2016-04-01

    Daily temperature (minimum and maximum) and precipitation datasets applied at regular grid points (10×10 km2) throughout Finland for 1961-2011 were analyzed with the aim to evaluate variability and trends in weather extremes on both national and spatial scale of the country and their relationships with atmospheric circulation patterns (ACPs). Recommending by the Expert Team on Climate Change Detection and Indices (ETCCDI), the extreme indices considered for daily temperature were frost days (FD), summer days (SD) and ice days (ID); and for daily precipitation were heavy precipitation days (R10), consecutive dry days (CDD), consecutive wet days (CWD), highest 1-day precipitation amount (RX1day), simple daily intensity index (SDII) and precipitation fraction due to 95th percentile of the reference period (R95pTOT). This study used the well-known influential ACPs for Finland climate variability: North Atlantic Oscillation (NAO), Arctic Oscillation (AO), East Atlantic (EA), East Atlantic/West Russia (EA/WR), Polar (POL), Scandinavia (SCA). The non-parametric Mann-Kendall test was used to determine significant historical trends in extreme indices, and the Spearman rank correlation (rho) to identify relationships between extreme indices and ACPs. For daily temperature indices, statistically significant (p<0.05) decreasing trends were found in ID (-0.40±0.34 days/year) and FD (-0.45±0.27 days/year) on a national scale of Finland during 1961-2011. The AO and EA/WR were most significant ACPs affecting variations in ID and FD, with rho = -0.73 and 0.42, respectively. For the daily precipitation extreme indices on the nation-wide of country over the study period (1961-2011), significant trends were only determined in SDII (0.01±0.00 mm/wet days year) and R95pTOT (0.19±0.09 %/year). Both of these indices (SDII and R95pTOT) showed the strongest correlations with the EA/WR pattern, with rho between from -0.42 to -0.34. The EA/WR pattern was also the most influential ACP for

  20. National Patterns in Environmental Injustice and Inequality: Outdoor NO2 Air Pollution in the United States

    PubMed Central

    Clark, Lara P.; Millet, Dylan B.; Marshall, Julian D.

    2014-01-01

    We describe spatial patterns in environmental injustice and inequality for residential outdoor nitrogen dioxide (NO2) concentrations in the contiguous United States. Our approach employs Census demographic data and a recently published high-resolution dataset of outdoor NO2 concentrations. Nationally, population-weighted mean NO2 concentrations are 4.6 ppb (38%, p<0.01) higher for nonwhites than for whites. The environmental health implications of that concentration disparity are compelling. For example, we estimate that reducing nonwhites’ NO2 concentrations to levels experienced by whites would reduce Ischemic Heart Disease (IHD) mortality by ∼7,000 deaths per year, which is equivalent to 16 million people increasing their physical activity level from inactive (0 hours/week of physical activity) to sufficiently active (>2.5 hours/week of physical activity). Inequality for NO2 concentration is greater than inequality for income (Atkinson Index: 0.11 versus 0.08). Low-income nonwhite young children and elderly people are disproportionately exposed to residential outdoor NO2. Our findings establish a national context for previous work that has documented air pollution environmental injustice and inequality within individual US metropolitan areas and regions. Results given here can aid policy-makers in identifying locations with high environmental injustice and inequality. For example, states with both high injustice and high inequality (top quintile) for outdoor residential NO2 include New York, Michigan, and Wisconsin. PMID:24736569

  1. National patterns in environmental injustice and inequality: outdoor NO2 air pollution in the United States.

    PubMed

    Clark, Lara P; Millet, Dylan B; Marshall, Julian D

    2014-01-01

    We describe spatial patterns in environmental injustice and inequality for residential outdoor nitrogen dioxide (NO2) concentrations in the contiguous United States. Our approach employs Census demographic data and a recently published high-resolution dataset of outdoor NO2 concentrations. Nationally, population-weighted mean NO2 concentrations are 4.6 ppb (38%, p<0.01) higher for nonwhites than for whites. The environmental health implications of that concentration disparity are compelling. For example, we estimate that reducing nonwhites' NO2 concentrations to levels experienced by whites would reduce Ischemic Heart Disease (IHD) mortality by ∼7,000 deaths per year, which is equivalent to 16 million people increasing their physical activity level from inactive (0 hours/week of physical activity) to sufficiently active (>2.5 hours/week of physical activity). Inequality for NO2 concentration is greater than inequality for income (Atkinson Index: 0.11 versus 0.08). Low-income nonwhite young children and elderly people are disproportionately exposed to residential outdoor NO2. Our findings establish a national context for previous work that has documented air pollution environmental injustice and inequality within individual US metropolitan areas and regions. Results given here can aid policy-makers in identifying locations with high environmental injustice and inequality. For example, states with both high injustice and high inequality (top quintile) for outdoor residential NO2 include New York, Michigan, and Wisconsin.

  2. A novel trapezoid fin pattern applicable for air-cooled heat sink

    NASA Astrophysics Data System (ADS)

    Chen, Chien-Hung; Wang, Chi-Chuan

    2015-11-01

    The present study proposed a novel step or trapezoid surface design applicable to air-cooled heat sink under cross flow condition. A total of five heat sinks were made and tested, and the corresponding fin patterns are (a) plate fin; (b) step fin (step 1/3, 3 steps); (c) 2-step fin (step 1/2, 2 steps); (d) trapezoid fin (trap 1/3, cutting 1/3 length from the rear end) and (e) trapezoid fin (trap 1/2, cutting 1/2 length from the rear end). The design is based on the heat transfer augmentation via (1) longer perimeter of entrance region and (2) larger effective temperature difference at the rear part of the heat sink. From the test results, it is found that either step or trapezoid design can provide a higher heat transfer conductance and a lower pressure drop at a specified frontal velocity. The effective conductance of trap 1/3 design exceeds that of plate surface by approximately 38 % at a frontal velocity of 5 m s-1 while retains a lower pressure drop of 20 % with its surface area being reduced by 20.6 %. For comparisons exploiting the overall thermal resistance versus pumping power, the resultant thermal resistance of the proposed trapezoid design 1/3, still reveals a 10 % lower thermal resistance than the plate fin surface at a specified pumping power.

  3. Inkjet patterned superhydrophobic paper for open-air surface microfluidic devices.

    PubMed

    Elsharkawy, Mohamed; Schutzius, Thomas M; Megaridis, Constantine M

    2014-03-21

    We present a facile approach for the fabrication of low-cost surface biomicrofluidic devices on superhydrophobic paper created by drop-casting a fluoroacrylic copolymer onto microtextured paper. Wettability patterning is performed with a common household printer, which produces regions of varying wettability by simply controlling the intensity of ink deposited over prespecified domains. The procedure produces surfaces that are capable of selective droplet sliding and adhesion, when inclined. Using this methodology, we demonstrate the ability to tune the sliding angles of 10 μL water droplets in the range from 13° to 40° by printing lines of constant ink intensity and varied width from 0.1 mm to 2 mm. We also formulate a simple model to predict the onset of droplet sliding on printed lines of known width and wettability. Experiments demonstrate open-air surface microfluidic devices that are capable of pumpless transport, mixing and rapid droplet sampling (~0.6 μL at 50 Hz). Lastly, post treatment of printed areas with pH indicator solutions exemplifies the utility of these substrates in point-of-care diagnostics, which are needed at geographical locations where access to sophisticated testing equipment is limited or non-existent.

  4. Influence of the Aral Sea negative water balance on its seasonal circulation and ventilation patterns: use of a 3d hydrodynamic model.

    NASA Astrophysics Data System (ADS)

    Sirjacobs, D.; Grégoire, M.; Delhez, E.; Nihoul, J.

    2003-04-01

    Within the context of the EU INCO-COPERNICUS program "Desertification in the Aral Sea Region: A study of the Natural and Anthropogenic Impacts" (Contract IAC2-CT-2000-10023), a large-scale 3D hydrodynamic model was adapted to address specifically the macroscale processes affecting the Aral Sea water circulation and ventilation. The particular goal of this research is to simulate the effect of lasting negative water balance on the 3D seasonal circulation, temperature, salinity and water-mixing fields of the Aral Sea. The original Aral Sea seasonal hydrodynamism is simulated with the average seasonal forcings corresponding to the period from 1956 to 1960. This first investigation concerns a period of relative stability of the water balance, before the beginning of the drying process. The consequences of the drying process on the hydrodynamic of the Sea will be studied by comparing this first results with the simulation representing the average situation for the years 1981 to 1985, a very low river flow period. For both simulation periods, the forcing considered are the seasonal fluctuations of wind fields, precipitation, evaporation, river discharge and salinity, cloud cover, air temperature and humidity. The meteorological forcings were adapted to the common optimum one-month temporal resolution of the available data sets. Monthly mean kinetic energy flux and surface tensions were calculated from daily ECMWF wind data. Monthly in situ precipitation, surface air temperature and humidity fields were interpolated from data obtained from the Russian Hydrological and Meteorological Institute. Monthly water discharge and average salinity of the river water were considered for both Amu Darya and Syr Darya river over each simulation periods. The water mass conservation routines allowed the simulation of a changing coastline by taking into account local drying and flooding events of particular grid points. Preliminary barotropic runs were realised (for the 1951

  5. Statistical downscaling of general-circulation-model- simulated average monthly air temperature to the beginning of flowering of the dandelion (Taraxacum officinale) in Slovenia

    NASA Astrophysics Data System (ADS)

    Bergant, Klemen; Kajfež-Bogataj, Lučka; Črepinšek, Zalika

    2002-02-01

    Phenological observations are a valuable source of information for investigating the relationship between climate variation and plant development. Potential climate change in the future will shift the occurrence of phenological phases. Information about future climate conditions is needed in order to estimate this shift. General circulation models (GCM) provide the best information about future climate change. They are able to simulate reliably the most important mean features on a large scale, but they fail on a regional scale because of their low spatial resolution. A common approach to bridging the scale gap is statistical downscaling, which was used to relate the beginning of flowering of Taraxacum officinale in Slovenia with the monthly mean near-surface air temperature for January, February and March in Central Europe. Statistical models were developed and tested with NCAR/NCEP Reanalysis predictor data and EARS predictand data for the period 1960-1999. Prior to developing statistical models, empirical orthogonal function (EOF) analysis was employed on the predictor data. Multiple linear regression was used to relate the beginning of flowering with expansion coefficients of the first three EOF for the Janauary, Febrauary and March air temperatures, and a strong correlation was found between them. Developed statistical models were employed on the results of two GCM (HadCM3 and ECHAM4/OPYC3) to estimate the potential shifts in the beginning of flowering for the periods 1990-2019 and 2020-2049 in comparison with the period 1960-1989. The HadCM3 model predicts, on average, 4 days earlier occurrence and ECHAM4/OPYC3 5 days earlier occurrence of flowering in the period 1990-2019. The analogous results for the period 2020-2049 are a 10- and 11-day earlier occurrence.

  6. Analysis of weather patterns associated with air quality degradation and potential health impacts

    EPA Science Inventory

    Emissions from anthropogenic and natural sources into the atmosphere are determined in large measure by prevailing weather conditions through complex physical, dynamical and chemical processes. Air pollution episodes are characterized by degradation in air quality as reflected by...

  7. Mountains and Tropical Circulation

    NASA Astrophysics Data System (ADS)

    Naiman, Z.; Goodman, P. J.; Krasting, J. P.; Malyshev, S.; Russell, J. L.; Stouffer, R. J.

    2015-12-01

    Observed tropical convection exhibits zonal asymmetries that strongly influence spatial precipitation patterns. The drivers of changes to this zonally-asymmetric Walker circulation on decadal and longer timescales have been the focus of significant recent research. Here we use two state-of-the-art earth system models to explore the impact of earth's mountains on the Walker circulation. When all land-surface topography is removed, the Walker circulation weakens by 33-59%. There is a ~30% decrease in global, large-scale upward vertical wind velocities in the middle of the troposphere, but only minor changes in global average convective mass flux, precipitation, surface and sea-surface temperatures. The zonally symmetric Hadley circulation is also largely unchanged. Following the spatial pattern of changes to large-scale vertical wind velocities, precipitation becomes less focused over the tropics. The weakening of the Walker circulation, but not the Hadley circulation, is similar to the behavior of climate models during radiative forcing experiments: in our simulations, the weakening is associated with changes in vertical wind velocities, rather than the hydrologic cycle. These results indicate suggest that mountain heights may significantly influence the Walker circulation on geologic time scales, and observed changes in tropical precipitation over millions of years may have been forced by changes in tropical orography.

  8. An introduction to aeolian dust dynamics recorded in the Stari Slankamen loess sequence (Vojvodina, Serbia) - Implications for past atmospheric circulation patterns of Eurasia

    NASA Astrophysics Data System (ADS)

    Stender, J.; Lukic, T.; Milojkovic, N.; Markovic, S.; Machalett, B.

    2008-12-01

    Loess sequences provide a direct proxy for the sedimentation dynamics of atmospheric dust, giving important information about the origin of the mineral aerosols and past palaeoclimatic conditions at that time of deposition. The conditions that determine the areas of origin, the transport and distribution of the aeolian material, are being accentuated by the dynamic process structures at the interface of the land surface and the atmosphere. Eventually this may allow the reconstruction of past atmospheric circulation patterns through high resolution loess investigations at different loess sites. The Stari Slankamen loess-palaeosol sequence is situated in the eastern part of the Srem Loess Plateau on the right bank of the Danube near by the river mouth of the Tisza into the Danube. Eight loess layers were distinguished, intercalated by nine pedocomplexes. The sequence under study has a total thickness of approximately 45 m. According to previous investigations the Stari Slankamen loess site is considered as one of the most important sections in the Pannonian basin. In this paper we present the first results of highly resolved grain size studies of the loess section Stari Slankamen. During fieldwork samples for grain size were taken at 2 cm intervals from the loess and the palaeosols, respectively. Particle size measurements of all samples were processed on a Beckman Coulter LS 13320 PIDS laser sizer with auto-prep station to provide a dynamic range that spans from 0.04 to 2000 µm and ensure accuracy and reproducibility. The granulometric results show distinct variations within the silt fraction and allow a clear distinction between cold and warm cycles. They show an important coherence between the type of dust sedimentation and the prevailing climate and offer insight into past atmospheric circulations of SE-Europe. Our results fundamentally contribute to a better understanding of interhemispheric teleconnections between Eurasian climate systems.

  9. Spatiotemporal Patterns, Monitoring Network Design, and Environmental Justice of Air Pollution in the Phoenix Metropolitan Region: A Landscape Approach

    NASA Astrophysics Data System (ADS)

    Pope, Ronald L.

    Air pollution is a serious problem in most urban areas around the world, which has a number of negative ecological and human health impacts. As a result, it's vitally important to detect and characterize air pollutants to protect the health of the urban environment and our citizens. An important early step in this process is ensuring that the air pollution monitoring network is properly designed to capture the patterns of pollution and that all social demographics in the urban population are represented. An important aspect in characterizing air pollution patterns is scale in space and time which, along with pattern and process relationships, is a key subject in the field of landscape ecology. Thus, using multiple landscape ecological methods, this dissertation research begins by characterizing and quantifying the multi-scalar patterns of ozone (O3) and particulate matter (PM10) in the Phoenix, Arizona, metropolitan region. Results showed that pollution patterns are scale-dependent, O3 is a regionally-scaled pollutant at longer temporal scales, and PM10 is a locally-scaled pollutant with patterns sensitive to season. Next, this dissertation examines the monitoring network within Maricopa County. Using a novel multiscale indicator-based approach, the adequacy of the network was quantified by integrating inputs from various academic and government stakeholders. Furthermore, deficiencies were spatially defined and recommendations were made on how to strengthen the design of the network. A sustainability ranking system also provided new insight into the strengths and weaknesses of the network. Lastly, the study addresses the question of whether distinct social groups were experiencing inequitable exposure to pollutants - a key issue of distributive environmental injustice. A novel interdisciplinary method using multi-scalar ambient pollution data and hierarchical multiple regression models revealed environmental inequities between air pollutants and race, ethnicity

  10. Understanding temporal patterns and characteristics of air quality in Beijing: A local and regional perspective

    NASA Astrophysics Data System (ADS)

    Chen, Ziyue; Xu, Bing; Cai, Jun; Gao, Bingbo

    2016-02-01

    Sources, characteristics and seasonal variation of airborne pollutants in China, especially in Beijing, have been massively examined. However, most studies analyze local air quality from an isolated perspective and interactions between local and regional air quality have not been fully considered. This research attempts to evaluate Beijing air quality at the local and regional scale. The weighted cross correlogram spectral matching (CCSM) and convergent cross mapping (CCM) method are employed for similarity and causality analysis respectively. At the local scale, the air quality in Beijing experiences frequent and sudden change, yet changes smoothly across a day's time. At the regional scale, the air quality in Beijing and four neighboring cities is compared. The result suggests that although air quality in Beijing and neighboring cities is of some differences, strong bidirectional coupling exists between the local and regional air quality. The research indicates that air quality in Beijing is better than the general situation in this region, and Tianjin should be a good comparative site for monitoring and evaluating air quality in Beijing. This research provides a feasible methodology for comprehensive analysis of local air quality at multiple scales, which may shed some lights on the forthcoming implementation of local air quality evaluation.

  11. [Effect of air-electric fields on driving and reaction patterns. Test subjects in the car driving simulator (author's transl)].

    PubMed

    Anselm, D; Danner, M; Kirmaier, N; König, H L; Müller-Limmroth, W; Reis, A; Schauerte, W

    1977-06-10

    In the relevant frequency range of about 10 Hertz cars can be considered very largely as Faraday cages and consequently as screens against air-electric fields. This may have a negative influence on driving and reaction patterns as a result. In an extensive investigation 48 subjects in a driving simulator were exposed to definite artificially produced air-electric fields. The self-rating of the performance and concentration of the subjects, reaction times and driving errors were determined. While the reaction times remained practically constant, the driving behavior of the subjects improved.

  12. THE ROLE OF COLD-AIR DRAINAGE IN EXPLAINING SPATIAL PATTERNS OF TEMPERATURE TRENDS IN THE WESTERN U.S

    NASA Astrophysics Data System (ADS)

    Pepin, N. C.; Daly, C.; Lundquist, J. D.

    2009-12-01

    Understanding spatial patterns of climate change in the western U.S. is of fundamental importance to understanding impacts on the landscape. Because much of the western U.S. is topographically complex, and shows distinct microclimates, there is no reason therefore to expect past or future patterns of change to be spatially smooth. In particular cold air drainage in mountain valleys causes decoupling of the temperature regime in many locations from the free atmosphere. This is a major feature of the western U.S. climate which is often dominated by relatively cloud-free high pressure conditions. We investigate here whether this decoupling has seen significant temporal change in the past, and the implications of such a change for patterns of warming observed across the western U.S. We analyse temperature trends from 494 long-term weather stations in the western U.S. for the period 1948-2006, from the GHCNv2 dataset, supplemented by additional COOP stations. There is a range of topographic incision and elevation in the sites chosen. At each location we derive monthly synoptic indices representative of the degree of anticyclonicity vs cyclonicity using NCEP/NCAR 700 mb reanalysis pressure fields. The number of anticyclonic days minus the number of cyclonic days (A-C) is strongly related to temperature anomalies at exposed convex sites and hilltops where the free atmosphere controls the temperature signal. At cold air drainage sites which tend to be in topographic concavities the relationship is much weaker. We use the gradient of the A-C/temperature relationship to represent a coupling index which is high at exposed free-air locations and low at cold-air drainage locations. There are clear relationships between the past rate of warming and this coupling index across the western U.S. but these are seasonally determined. On a mean annual basis there are no strong relationships between temperature trend magnitude, elevation, the degree of topographic incision or the

  13. Seasonal variations in 228Ra/226Ra ratio within coastal waters of the Sea of Japan: implications for water circulation patterns in coastal areas.

    PubMed

    Inoue, M; Tanaka, K; Watanabe, S; Kofuji, H; Yamamoto, M; Komura, K

    2006-01-01

    In this study, low-background gamma-spectrometry was used to determine the (228)Ra/(226)Ra ratio of 131 coastal water samples from various environments around Honshu Island, Japan (mainly around Noto Peninsula) at 1-3 month intervals from April 2003 until September 2005. Spatial variation in (228)Ra/(226)Ra ratios was also assessed by analyzing 34 coastal water samples from five areas within the Sea of Japan during May and June 2004. The (228)Ra/(226)Ra ratio of coastal water from all sites around Noto Peninsula shows seasonal variation, with minimum values during summer ((228)Ra/(226)Ra=0.7) and maximum values during autumn-winter ((228)Ra/(226)Ra=1.7-2). This seasonal variation is similar to that recorded for coastal water between Tsushima Strait and Noto Peninsula. The measured lateral variation in (228)Ra/(226)Ra ratios within coastal water between Tsushima Strait and Noto Peninsula is only minor (0.5-0.7; May-June 2004). Coastal waters from two other sites (Pacific shore and Tsugaru Strait, north Honshu) show no clear seasonal variation in (228)Ra/(226)Ra ratio. These measured variations in (228)Ra/(226)Ra ratio, especially the temporal variations, have important implications for seasonal changes in patterns of coastal water circulation within the Sea of Japan.

  14. Huntington beach shoreline contamination investigation, phase III: coastal circulation and transport patterns : the likelihood of OCSD's plume impacting Huntington beach shoreline

    USGS Publications Warehouse

    Noble, Marlene; Xu, Jingping; Rosenfeld, Leslie; Largier, John; Hamilton, Peter; Jones, Burt; Robertson, George

    2003-01-01

    A consortium of agencies have conducted an extensive investigation of the coastal ocean circulation and transport pathways off Huntington Beach, with the aim of identifying any causal links that may exist between the offshore discharge of wastewater by OCSD and the significant bacterial contamination observed along the Huntington Beach shoreline. This is the third study supported by OCSD to determine possible land-based and coa Although the study identifies several possible coastal ocean pathways by which diluted wastewater may be transported to the beach, including internal tide, sea-breeze and subtidal flow features, there were no direct observations of either the high bacteria concentrations seen in the OCSD plume at the shelf break reaching the shoreline in significant levels or of an association between the existence of a coastal ocean process and beach contamination at or above AB411 levels. It is concluded that the OCSD plume is not a major cause of beach contamination; no causal links could be demonstrated. This conclusion is based on the absence of direct observation of plume-beach links, on analysis of the spatial and temporal patterns of shoreline contamination and coastal ocean processes, and on the observation of higher levels of contamination at the beach than in the plume.

  15. Determination of air movement in stored grain as a factor in dynamic dispersion and distribution patterns of gaseous pesticides (fumigants).

    PubMed

    Berck, B

    1975-05-01

    The new research reported herein was motivated by variations in distribution-persistence patterns of fumigant residues (BERCK, 1974). The current developmental program is still underway. In the meantime, measurement of picoliter amounts of SF6 in air by GC equipped with a Ni63 EC detector has been proven useful over an airflow range of 10(-4) to 50 mph, representing a factor of 500,000 in differences in air velocity. Diverse applications have been outlined herein. This is the first case on record where measurement of unassisted airflow in the interstitial air of stored grain has been successfully executed, and which enabled determination of airflow speeds in the range of 0.5 to 7.5 times 10(-4) mph (=3 to 45 inches per hour).

  16. "Exposure Track"-The Impact of Mobile-Device-Based Mobility Patterns on Quantifying Population Exposure to Air Pollution.

    PubMed

    Nyhan, Marguerite; Grauwin, Sebastian; Britter, Rex; Misstear, Bruce; McNabola, Aonghus; Laden, Francine; Barrett, Steven R H; Ratti, Carlo

    2016-09-01

    Air pollution is now recognized as the world's single largest environmental and human health threat. Indeed, a large number of environmental epidemiological studies have quantified the health impacts of population exposure to pollution. In previous studies, exposure estimates at the population level have not considered spatially- and temporally varying populations present in study regions. Therefore, in the first study of it is kind, we use measured population activity patterns representing several million people to evaluate population-weighted exposure to air pollution on a city-wide scale. Mobile and wireless devices yield information about where and when people are present, thus collective activity patterns were determined using counts of connections to the cellular network. Population-weighted exposure to PM2.5 in New York City (NYC), herein termed "Active Population Exposure" was evaluated using population activity patterns and spatiotemporal PM2.5 concentration levels, and compared to "Home Population Exposure", which assumed a static population distribution as per Census data. Areas of relatively higher population-weighted exposures were concentrated in different districts within NYC in both scenarios. These were more centralized for the "Active Population Exposure" scenario. Population-weighted exposure computed in each district of NYC for the "Active" scenario were found to be statistically significantly (p < 0.05) different to the "Home" scenario for most districts. In investigating the temporal variability of the "Active" population-weighted exposures determined in districts, these were found to be significantly different (p < 0.05) during the daytime and the nighttime. Evaluating population exposure to air pollution using spatiotemporal population mobility patterns warrants consideration in future environmental epidemiological studies linking air quality and human health. PMID:27518311

  17. "Exposure Track"-The Impact of Mobile-Device-Based Mobility Patterns on Quantifying Population Exposure to Air Pollution.

    PubMed

    Nyhan, Marguerite; Grauwin, Sebastian; Britter, Rex; Misstear, Bruce; McNabola, Aonghus; Laden, Francine; Barrett, Steven R H; Ratti, Carlo

    2016-09-01

    Air pollution is now recognized as the world's single largest environmental and human health threat. Indeed, a large number of environmental epidemiological studies have quantified the health impacts of population exposure to pollution. In previous studies, exposure estimates at the population level have not considered spatially- and temporally varying populations present in study regions. Therefore, in the first study of it is kind, we use measured population activity patterns representing several million people to evaluate population-weighted exposure to air pollution on a city-wide scale. Mobile and wireless devices yield information about where and when people are present, thus collective activity patterns were determined using counts of connections to the cellular network. Population-weighted exposure to PM2.5 in New York City (NYC), herein termed "Active Population Exposure" was evaluated using population activity patterns and spatiotemporal PM2.5 concentration levels, and compared to "Home Population Exposure", which assumed a static population distribution as per Census data. Areas of relatively higher population-weighted exposures were concentrated in different districts within NYC in both scenarios. These were more centralized for the "Active Population Exposure" scenario. Population-weighted exposure computed in each district of NYC for the "Active" scenario were found to be statistically significantly (p < 0.05) different to the "Home" scenario for most districts. In investigating the temporal variability of the "Active" population-weighted exposures determined in districts, these were found to be significantly different (p < 0.05) during the daytime and the nighttime. Evaluating population exposure to air pollution using spatiotemporal population mobility patterns warrants consideration in future environmental epidemiological studies linking air quality and human health.

  18. THE PATTERN OF AIR FLOW OUT OF THE MOUTH DURING SPEECH.

    ERIC Educational Resources Information Center

    LANE, H.; AND OTHERS

    SINCE THE 19TH CENTURY, KYMOGRAPHIC RECORDING OF TOTAL AIR FLOW OUT OF THE MOUTH HAS BEEN USED TO DIAGNOSE THE VARYING DURATIONS AND DEGREES OF CONSTRICTIONS OF THE VOCAL TRACT DURING SPEECH. THE PRESENT PROJECT ATTEMPTS TO INTRODUCE A SECOND DIMENSION TO RECORDINGS OF AIR FLOW OUT OF THE MOUTH--NAMELY, CROSS-SECTIONAL AREA OF FLOW--ON THE…

  19. Lung Circulation.

    PubMed

    Suresh, Karthik; Shimoda, Larissa A

    2016-04-01

    The circulation of the lung is unique both in volume and function. For example, it is the only organ with two circulations: the pulmonary circulation, the main function of which is gas exchange, and the bronchial circulation, a systemic vascular supply that provides oxygenated blood to the walls of the conducting airways, pulmonary arteries and veins. The pulmonary circulation accommodates the entire cardiac output, maintaining high blood flow at low intravascular arterial pressure. As compared with the systemic circulation, pulmonary arteries have thinner walls with much less vascular smooth muscle and a relative lack of basal tone. Factors controlling pulmonary blood flow include vascular structure, gravity, mechanical effects of breathing, and the influence of neural and humoral factors. Pulmonary vascular tone is also altered by hypoxia, which causes pulmonary vasoconstriction. If the hypoxic stimulus persists for a prolonged period, contraction is accompanied by remodeling of the vasculature, resulting in pulmonary hypertension. In addition, genetic and environmental factors can also confer susceptibility to development of pulmonary hypertension. Under normal conditions, the endothelium forms a tight barrier, actively regulating interstitial fluid homeostasis. Infection and inflammation compromise normal barrier homeostasis, resulting in increased permeability and edema formation. This article focuses on reviewing the basics of the lung circulation (pulmonary and bronchial), normal development and transition at birth and vasoregulation. Mechanisms contributing to pathological conditions in the pulmonary circulation, in particular when barrier function is disrupted and during development of pulmonary hypertension, will also be discussed. PMID:27065170

  20. Air-void embedded GaN-based light-emitting diodes grown on laser drilling patterned sapphire substrates

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Li, Yufeng; Wang, Shuai; Feng, Lungang; Xiong, Han; Su, Xilin; Yun, Feng

    2016-07-01

    Air-void structure was introduced in GaN-based blue light-emitting diodes (LED) with one-step growth on periodic laser drilling patterned sapphire substrate, which free of any photolithography or wet/dry etching process. The influence of filling factors (FF) of air-void on crystal quality and optical performance were investigate. Transmission electron microscopy images and micro-Raman spectroscopy indicated that the dislocation was bended and the partially compressed strain was released. When FF was 55.43%, compared with the LED structure grown on flat sapphire substrate, the incorporation of air-void was observed to reduce the compressed stress of ˜20% and the luminance intensity has improved by 128%. Together with the simulated reflection intensity enhancement by finite difference time-domain (FDTD) method, we attribute the enhanced optical performance to the combined contribution of strong back-side light reflection of air-void and better GaN epitaxial quality. This approach provides a simple replacement to the conventional air-void embedded LED process.

  1. Numerical Analysis of Air Pressure Effects on the Flow Pattern during the Filling of a Vertical Die Cavity

    NASA Astrophysics Data System (ADS)

    Hernández-Ortega, J. J.; Zamora, R.; López, J.; Faura, F.

    2011-05-01

    Porosity due to air entrapment in the molten metal during the injection process is one of the most important problems encountered in die-casting processes. The causes of air entrapment can be attributed mainly to the evolution of the free surface of the fluid flow during the filling and the use of inadequate air evacuation systems. Different studies of the main characteristics of the flow during the filling of a vertical die cavity can be found in the literature. In most of these studies, the effects of the air on the flow of molten metal during the injection are usually neglected. However, under certain conditions, specially when there is a poor evacuation of air through vents, these effects may substantially affect the filling pattern and the final amount of air trapped in the molten metal. The aim of this work is to study numerically the effects of air on the fluid flow during the early stages of the filling of a vertical die cavity with rectangular shape. To this end, numerical simulations of the fluid flow in the die cavity are carried out using a commercial CFD code (FLOW-3D) based on the SOLA-VOF approach to solve the coupling between the momentum and mass conservation equations and to treat the free surface. The main characteristics of the flow are analyzed for a wide range of operating conditions. Also, filling visualization experiments are carried out on a test bench for validation purpose using water as working fluid in a transparent die model and a high-speed camera. The viability of the numerical model used in the simulations is finally discussed.

  2. TROPICAL METEOROLOGY & Climate: Hadley Circulation

    SciTech Connect

    Lu, Jian; Vecchi, Gabriel A.

    2015-01-30

    The Hadley circulation, a prominent circulation feature characterized by rising air near the Equator and sinking air in the subtropics, defines the position of dry subtropical areas and is a fundamental regulator of the earth’s energy and momentum budgets. The character of the Hadley circulation, and its related precipitation regimes, exhibits variation and change in response to both climate variability and radiative forcing changes. The strength and position of the Hadley circulation change from year to year paced by El Niño and La Niña events. Over the last few decades of the twentieth century, the Hadley cell has expanded poleward in both hemispheres, with changes in atmospheric composition (including stratospheric ozone depletion and greenhouse gas increases) thought to have contributed to its expansion. This article introduces the basic phenomenology and driving mechanism of the Hadley circulation and discusses its variations under both natural and anthropogenic climate forcings.

  3. Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy

    NASA Astrophysics Data System (ADS)

    Underwood, S. Jeffrey; Schultz, Michael D.; Berti, Metteo; Gregoretti, Carlo; Simoni, Alessandro; Mote, Thomas L.; Saylor, Anthony M.

    2016-02-01

    The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydro-geologic events. In the past, debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass-wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of 3 days prior to debris flow events to gain insight into the synoptic-scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CF flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal colocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

  4. Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy

    NASA Astrophysics Data System (ADS)

    Underwood, S. J.; Schultz, M. D.; Berti, M.; Gregoretti, C.; Simoni, A.; Mote, T. L.; Saylor, A. M.

    2015-09-01

    The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydrogeologic events. In the past debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500 hPa pressure level plots of geopotential heights were constructed for a period of three days prior to debris flow events to gain insight into the synoptic scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CG flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60 min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal collocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation.

  5. HEPA air filter (image)

    MedlinePlus

    ... pet dander and other irritating allergens from the air. Along with other methods to reduce allergens, such ... controlling the amount of allergens circulating in the air. HEPA filters can be found in most air ...

  6. How much do carbon isotope measurements constrain glacial ocean circulation?

    NASA Astrophysics Data System (ADS)

    Schmittner, A.; Mix, A. C.

    2010-12-01

    Reconstructions of the isotopic composition of dissolved inorganic carbon in seawater (d13DIC) are often interpreted as a ventilation or circulation proxy in paleoceanography. The modern deep-sea distribution of d13C in dissolved inorganic carbon (d13DIC) is highly anti-correlated to macronutrient (PO4, NO3) and apparent oxygen utilization (AOU) patterns due to fractionation during photosynthetic carbon uptake by phytoplankton. Nutrient and AOU concentrations in freshly ventilated North Atlantic Deep Water, for example, are low (d13DIC is high), whereas older water masses contain more respired nutrients and (isotopically light) carbon and have high AOU. However, d13DIC is also influenced by fractionation during air sea gas exchange - a process that decouples d13DIC from changes in nutrients and AOU. Moreover, biological fractionation is not constant but spatially and temporally variable. Here we are using a new global three-dimensional model of stable carbon isotope cycling that includes variable biological and air-sea gas exchange fractionation effects in conjunction with modern and glacial d13C observations to reconstruct ocean circulation patterns. Model versions with different rates and patterns of ocean circulation are produced and the resulting d13C patterns are compared to a compilation of measurements from ocean sediment cores in a probabilistic approach. The method allows us to quantify the uncertainty of deep ocean mass fluxes given available d13C observations/reconstructions and provide a quantitative test of the assumption of d13C as a ventilation proxy.

  7. Evaluation of HCMM satellite data for estuarine tidal circulation patterns and thermal inertia soil moisture measurements. [Delaware Bay, Cooper River, and the Potomac River estuaries; Luverne, Minnesota, soil moisture, and water temperature of Lake Anna, Virginia

    NASA Technical Reports Server (NTRS)

    Wiesnet, D. R.; Mcginnis, D. F., Jr. (Principal Investigator); Matson, M.; Pritchard, J. A.

    1981-01-01

    Digital thermal maps of the Cooper River (SC) and the Potomac River estuaries were prepared from heat capacity mapping radiometer (HCMR) tapes. Tidal phases were correctly interpreted and verified. Synoptic surface circulation patterns were charted by location thermal fronts and water mass boundaries within the estuaries. Thermal anomalies were detected adjacent of a conventional power plant on the Potomac. Under optimum conditions, estuaries as small as the Cooper River can be monitored for generalized thermal/tidal circulation patterns by the HCMM-type IR sensors. The HCMM thermal inertia approach to estimating soil moisture at the Luverne (MN) test site was found to be unsatisfactory as a NESS operational satellite technique because of cloud cover interference. Thermal-IR data show similar structure of the Baltimore and Washington heat islands when compared to NOAA AVHRR thermal-IR data. Thermal anomalies from the warm water discharge water of a nuclear power plant were mapped in Lake Anna, Virginia.

  8. The pattern of northern hemisphere surface air temperature during prolonged periods of low solar output

    NASA Technical Reports Server (NTRS)

    Ruzmaikin, A.; Feyman, J.; Jiang, X.; Noone, D. C.; Waple, A. M.; Yung, Y. L.

    2004-01-01

    We show that the reconstructed sensitivity of the sea level temperature to long term solar forcing in the Northern Hemisphere is in very good agreement with the empirical temperature pattern corresponding to changes of the North Annular Mode (NAM).

  9. Traffic-related air pollution and circulating levels of total and allergen-specific IgE among children in Detroit, Michigan

    EPA Science Inventory

    Introduction: There is a growing body of literature suggesting a relationship between traffic-related air pollution and allergic health outcomes. Animal studies have demonstrated that air pollution, particularly diesel exhaust particles, may stimulate or enhance atopic responses...

  10. The radio emission pattern of air showers as measured with LOFAR—a tool for the reconstruction of the energy and the shower maximum

    NASA Astrophysics Data System (ADS)

    Nelles, A.; Buitink, S.; Corstanje, A.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Rachen, J. P.; Rossetto, L.; Schellart, P.; Scholten, O.; ter Veen, S.; Thoudam, S.; Trinh, T. N. G.

    2015-05-01

    The pattern of the radio emission of air showers is finely sampled with the Low-Frequency ARray (LOFAR). A set of 382 measured air showers is used to test a fast, analytic parameterization of the distribution of pulse powers. Using this parameterization we are able to reconstruct the shower axis and give estimators for the energy of the air shower as well as the distance to the shower maximum.

  11. Peripheral circulation.

    PubMed

    Laughlin, M Harold; Davis, Michael J; Secher, Niels H; van Lieshout, Johannes J; Arce-Esquivel, Arturo A; Simmons, Grant H; Bender, Shawn B; Padilla, Jaume; Bache, Robert J; Merkus, Daphne; Duncker, Dirk J

    2012-01-01

    Blood flow (BF) increases with increasing exercise intensity in skeletal, respiratory, and cardiac muscle. In humans during maximal exercise intensities, 85% to 90% of total cardiac output is distributed to skeletal and cardiac muscle. During exercise BF increases modestly and heterogeneously to brain and decreases in gastrointestinal, reproductive, and renal tissues and shows little to no change in skin. If the duration of exercise is sufficient to increase body/core temperature, skin BF is also increased in humans. Because blood pressure changes little during exercise, changes in distribution of BF with incremental exercise result from changes in vascular conductance. These changes in distribution of BF throughout the body contribute to decreases in mixed venous oxygen content, serve to supply adequate oxygen to the active skeletal muscles, and support metabolism of other tissues while maintaining homeostasis. This review discusses the response of the peripheral circulation of humans to acute and chronic dynamic exercise and mechanisms responsible for these responses. This is accomplished in the context of leading the reader on a tour through the peripheral circulation during dynamic exercise. During this tour, we consider what is known about how each vascular bed controls BF during exercise and how these control mechanisms are modified by chronic physical activity/exercise training. The tour ends by comparing responses of the systemic circulation to those of the pulmonary circulation relative to the effects of exercise on the regional distribution of BF and mechanisms responsible for control of resistance/conductance in the systemic and pulmonary circulations.

  12. Techniques of low technology sampling of air pollution by metals: a comparison of concentrations and map patterns.

    PubMed

    Lloyd, O L; Gailey, F A

    1987-07-01

    During a 17 month survey of air pollution in the town of Armadale, central Scotland, the concentrations of some metals (iron, manganese, zinc, lead, copper, chrome, nickel, cadmium, and cobalt) were measured in seven types of low technology sampler--four indigenous and three transplanted--at 47 sites. The geographical patterns of the concentrations in the samplers were compared on two types of map. For most metals, sites with high concentrations were present close to the foundry and also in the north of the town. The differences between the patterns of pollution shown by the various types of sampler probably reflected differing mechanisms for collection and different affinities for various sizes and types of metal particle.

  13. Field-scale tests for determining mixing patterns associated with coarse-bubble air diffuser configurations, Egan Quarry, Illinois

    USGS Publications Warehouse

    Hornewer, N.J.; Johnson, G.P.; Robertson, D.M.; Hondzo, Miki

    1997-01-01

    The U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, Chicago District did field-scale tests in August-September 1996 to determine mixing patterns associated with different configurations of coarse-bubble air diffusers. The tests were done in an approximately 13-meter deep quarry near Chicago, Ill. Three-dimensional velocity, water-temperature, dissolved oxygen concentration, and specific-conductivity profiles were collected from locations between approximately 2 to 30 meters from the diffusers for two sets of five test configurations; one set for stratified and one set for destratified conditions in the quarry. The data-collection methods and instrumentation used to characterize mixing patterns and interactions of coarse-bubble diffusers were successful. An extensive data set was collected and is available to calibrate and verify aeration and stratification models, and to characterize basic features of bubble-plume interaction.

  14. Distinct synoptic patterns and air masses responsible for long-range desert dust transport and sea spray in Palermo, Italy

    NASA Astrophysics Data System (ADS)

    Dimitriou, K.; Paschalidou, A. K.; Kassomenos, P. A.

    2016-09-01

    Undoubtedly, anthropogenic emissions carry a large share of the risk posed on public health by particles exposure in urban areas. However, natural emissions, in the form of desert dust and sea spray, are well known to contribute significantly to the PM load recorded in many Mediterranean environments, posing an extra risk burden on public health. In the present paper, we examine the synoptic climatology in a background station in Palermo, Italy, through K-means clustering of the mean sea-level pressure (MSLP) maps, in an attempt to associate distinct synoptic patterns with increased PM10 levels. Four-day backward trajectory analysis is then applied, in order to study the origins and pathways of air masses susceptible of PM10 episodes. It is concluded that a number of atmospheric patterns result in several kind of flows, namely south, west, and slow-moving/stagnant flows, associated with long-range dust transport and sea spray.

  15. [Relationship between urban green-land landscape patterns and air pollution in the central district of Yichang city].

    PubMed

    Shao, Tianyi; Zhou, Zhixiang; Wang, Pengcheng; Tang, Wanpeng; Liu, Xuequan; Hu, Xingyi

    2004-04-01

    In this paper, four types of landscape structures and their green-land landscape patterns, including the landscapes of dominant green-land patch pattern, even green-land patch pattern, dominant wooded corridor pattern and building or concrete covering pattern (control) in the central district of Yichang city in Hubei Province, were analyzed respectively on the basis of landscape ecological theory. The atmospheric noise and the contents of SO2, NOx and total suspension particle (TSP) of the landscapes were monitored respectively by comparative method. The results showed that the landscape of building or concrete covering pattern (control) was mostly composed of woodless corridors and building or concrete covering patches with the tiptop green-land fragmentation index (18.125 3 ind x hm(-2)) and only had 1.00% green-land coverage, which had a relatively higher atmospheric noise and the highest TSP content in the landscape. The landscape of dominant green-land patch pattern had the highest green-land coverage (up to 43.59%) dominated by great green-land patches and the least fragmentation index (0.453 9 ind x hm(-2)), in which, the atmospheric noise weakened by 28.12% and the TSP content reduced significantly by 86.42%, comparing to the control. The landscape of even green-land patch pattern had the relatively lower green-land coverage (11.34%) and fragmentation index (2.751 1 ind x hm(-2)), which was mainly composed of the middle or small green-land patches and wooded corridors with a regular distribution. In the landscape, the TSP content reduced obviously by 46.62% of the control, while the effect of dust retention was only 53.95% of that in the landscape of dominant green-land patch pattern. In the landscape of dominant wooded corridor pattern, which was a traffic center and turned into a main pollution resource in the city, there were a relatively higher green-land fragmentation index (6.870 0 ind x hm(-2)) and the highest wooded corridor density (0.844 3 hm x hm

  16. Influence of synoptic and local atmospheric patterns on PM10 air pollution levels: a model application to Naples (Italy)

    NASA Astrophysics Data System (ADS)

    Fortelli, Alberto; Scafetta, Nicola; Mazzarella, Adriano

    2016-10-01

    We investigate the relationship between synoptic/local meteorological patterns and PM10 air pollution levels in the metropolitan area of Naples, Italy. We found that severe air pollution crises occurred when the 850 and 500 hpa geopotential heights and their relative temperatures present maximum values above the city. The most relevant synoptic parameter was the 850 hPa geopotential height, which is located about 1500 m of altitude. We compared local meteorological conditions (specifically wind stress, rain amount and thermal inversion) against the urban air pollution levels from 2009 to 2013. We found several empirical criteria for forecasting high daily PM10 air pollution levels in Naples. Pollution crises occurred when (a) the wind stress was between 1 and 2 m/s, (b) the thermal inversion between two strategic locations was at least 3°C/200 m and (c) it did not significantly rain for at least 7 days. Beside these meteorological conditions, severe pollution crises occurred also during festivals when fireworks and bonfires are lighted, and during anomalous breeze conditions and severe fire accidents. Finally, we propose a basic model to predict PM10 concentration levels from local meteorological conditions that can be easily forecast a few days in advance. The synthetic PM10 record predicted by the model was found to correlate with the PM10 observations with a correlation coefficient close to 0.80 with a confidence level greater than 99%. The proposed model is expected to provide reliable information to city officials to carry out practical strategies to mitigate air pollution effects. Although the proposed model equation is calibrated on the topographical and meteorological conditions of Naples, it should be easily adaptable to alternative locations.

  17. Fjord water circulation patterns and dysoxic/anoxic conditions in a Mediterranean semi-enclosed embayment in the Amvrakikos Gulf, Greece

    NASA Astrophysics Data System (ADS)

    Ferentinos, George; Papatheodorou, George; Geraga, Maria; Iatrou, Margarita; Fakiris, Elias; Christodoulou, Dimitris; Dimitriou, Evagelos; Koutsikopoulos, Constantin

    2010-08-01

    Oceanographic research in the Amvrakikos Gulf in Western Greece, a semi-enclosed embayment isolated from the Ionian Sea by a narrow, shallow sill, has shown that it is characterised by a fjord-like oceanographic regime. The Gulf is characterised by a well-stratified two layer structure in the water column made up of a surface layer and a bottom layer that are separated by a strong pycnocline. At the entrance over the sill, there is a brackish water outflow in the surface water and a saline water inflow in the near-bed region. This morphology and water circulation pattern makes the Amvrakikos Gulf the only Mediterranean Sea fjord. The investigations have also shown that the surface layer is well oxygenated, whereas in the pycnocline, the dissolved oxygen (DO) declines sharply and finally attains a value of zero, thus dividing the water column into oxic, dysoxic and anoxic environments. At the dysoxic/anoxic interface, at a depth of approximately 35 m, a sharp redox cline develops with Eh values between 0 and 120 mV occurring above and values between 0 and -250 mV occurring below, where oxic and anoxic biochemical processes prevail, respectively. On the seafloor underneath the anoxic waters, a black silt layer and a white mat cover resembling Beggiatoa-like cells are formed. The dysoxic/anoxic conditions appeared during the last 20 to 30 years and have been caused by the excessive use of fertilisers, the increase in animal stocks, intensive fish farming and domestic effluents. The inflicted dysoxia/anoxia has resulted in habitat loss on the seafloor over an area that makes up just over 50% of the total Gulf area and approximately 28% of the total water volume. Furthermore, anoxia is also considered to have been responsible for the sudden fish mortality which occurred in aquaculture rafts in the Gulf in February 2008. Therefore, anoxic conditions can be considered to be a potential hazard to the ecosystem and to the present thriving fishing and mariculture industry in

  18. Pattern recognition methods and air pollution source identification. [based on wind direction

    NASA Technical Reports Server (NTRS)

    Leibecki, H. F.; King, R. B.

    1978-01-01

    Directional air samplers, used for resolving suspended particulate matter on the basis of time and wind direction were used to assess the feasibility of characterizing and identifying emission source types in urban multisource environments. Filters were evaluated for 16 elements and X-ray fluorescence methods yielded elemental concentrations for direction, day, and the interaction of direction and day. Large numbers of samples are necessary to compensate for large day-to-day variations caused by wind perturbations and/or source changes.

  19. Separating the influence of projected changes in air temperature and wind on patterns of sea level change and ocean heat content

    NASA Astrophysics Data System (ADS)

    Saenko, Oleg A.; Yang, Duo; Gregory, Jonathan M.; Spence, Paul; Myers, Paul G.

    2015-08-01

    We present ocean model sensitivity experiments aimed at separating the influence of the projected changes in the "thermal" (near-surface air temperature) and "wind" (near-surface winds) forcing on the patterns of sea level and ocean heat content. In the North Atlantic, the distribution of sea level change is more due to the "thermal" forcing, whereas it is more due to the "wind" forcing in the North Pacific; in the Southern Ocean, the "thermal" and "wind" forcing have a comparable influence. In the ocean adjacent to Antarctica the "thermal" forcing leads to an inflow of warmer waters on the continental shelves, which is somewhat attenuated by the "wind" forcing. The structure of the vertically integrated heat uptake is set by different processes at low and high latitudes: at low latitudes it is dominated by the heat transport convergence, whereas at high latitudes it represents a small residual of changes in the surface flux and advection of heat. The structure of the horizontally integrated heat content tendency is set by the increase of downward heat flux by the mean circulation and comparable decrease of upward heat flux by the subgrid-scale processes; the upward eddy heat flux decreases and increases by almost the same magnitude in response to, respectively, the "thermal" and "wind" forcing. Regionally, the surface heat loss and deep convection weaken in the Labrador Sea, but intensify in the Greenland Sea in the region of sea ice retreat. The enhanced heat flux anomaly in the subpolar Atlantic is mainly caused by the "thermal" forcing.

  20. Use of weather types to disaggregate general circulation model predictions

    USGS Publications Warehouse

    Hay, L.E.; McCabe, G.J.; Wolock, D.M.; Ayers, M.A.

    1992-01-01

    A method has been developed that uses weather-type analysis as a tool to spatially disaggregate GCM predictions to make them useful for water resource studies. The method has been applied to the Delaware River basin to predict the effects of doubling atmospheric carbon dioxide on precipitation patterns in the region. An application of the technique to the Delaware River basin indicates that future climate conditions will show minimal changes in weather-type frequency, implying that air circulation patterns will remain unchanged -from Authors

  1. Twentieth-century atmospheric river activity along the west coasts of Europe and North America: algorithm formulation, reanalysis uncertainty and links to atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Brands, S.; Gutiérrez, J. M.; San-Martín, D.

    2016-04-01

    A new atmospheric-river detection and tracking scheme based on the magnitude and direction of integrated water vapour transport is presented and applied separately over 13 regions located along the west coasts of Europe (including North Africa) and North America. Four distinct reanalyses are considered, two of which cover the entire twentieth-century: NOAA-CIRES Twentieth Century Reanalysis v2 (NOAA-20C) and ECMWF ERA-20C. Calculations are done separately for the OND and JFM-season and, for comparison with previous studies, for the ONDJFM-season as a whole. Comparing the AR-counts from NOAA-20C and ERA-20C with a running 31-year window looping through 1900-2010 reveals differences in the climatological mean and inter-annual variability which, at the start of the twentieth-century, are much more pronounced in western North America than in Europe. Correlating European AR-counts with the North Atlantic Oscillation (NAO) reveals a pattern reminiscent of the well-know precipitation dipole which is stable throughout the entire century. A similar analysis linking western North American AR-counts to the North Pacific index (NPI) is hampered by the aforementioned poor reanalysis agreement at the start of the century. During the second half of the twentieth-century, the strength of the NPI-link considerably varies with time in British Columbia and the Gulf of Alaska. Considering the period 1950-2010, AR-counts are then associated with other relevant large-scale circulation indices such as the East Atlantic, Scandinavian, Pacific-North American and West Pacific patterns (EA, SCAND, PNA and WP). Along the Atlantic coastline of the Iberian Peninsula and France, the EA-link is stronger than the NAO-link if the OND season is considered and the SCAND-link found in northern Europe is significant during both seasons. Along the west coast of North America, teleconnections are generally stronger during JFM in which case the NPI-link is significant in any of the five considered

  2. Understanding and Portraying the Global Atmospheric Circulation.

    ERIC Educational Resources Information Center

    Harrington, John, Jr.; Oliver, John E.

    2000-01-01

    Examines teaching models of atmospheric circulation and resultant surface pressure patterns, focusing on the three-cell model and the meaning of meridional circulation as related to middle and high latitudes. Addresses the failure of the three-cell model to explain seasonal variations in atmospheric circulation. Suggests alternative models. (CMK)

  3. Three dimensional simulations of pattern formation during high-pressure, freely localized microwave breakdown in air

    SciTech Connect

    Kourtzanidis, K. Boeuf, J. P.; Rogier, F.

    2014-12-15

    Recent experiments have demonstrated that a freely localized 100 GHz microwave discharge can propagate towards the microwave source with high speed, forming a complex pattern of self-organized filaments. We present three-dimensional simulations of the formation and propagation of such patterns that reveal more information on their nature and interaction with the electromagnetic waves. The developed three-dimensional Maxwell-plasma solver permits the study of different forms of incident field polarization. Results for linear and circular polarization of the wave are presented and comparisons with recent experiments show a good overall agreement. The three dimensional simulations provide a quantitative analysis of the parameters controlling the time and length scales of the strongly non-linear plasma dynamics and could be useful for potential microwave plasma applications such as aerodynamic flow and combustion control.

  4. Precipitation chemistry and corresponding transport patterns of influencing air masses at Huangshan Mountain in East China

    NASA Astrophysics Data System (ADS)

    Shi, ChunE; Deng, Xueliang; Yang, Yuanjian; Huang, Xiangrong; Wu, Biwen

    2014-09-01

    One hundred and ten samples of rainwater were collected for chemical analysis at the summit of Huangshan Mountain, a high-altitude site in East China, from July 2010 to June 2011. The volume-weighted-mean (VWM) pH for the whole sampling period was 5.03. SO{4/2-} and Ca2+ were the most abundant anion and cation, respectively. The ionic concentrations varied monthly with the highest concentrations in winter/spring and the lowest in summer. Evident inter-correlations were found among most ions, indicating the common sources for some species and fully mixing characteristics of the alpine precipitation chemistry. The VWM ratio of [SO{4/2-}]/[NO{3/-}] was 2.54, suggesting the acidity of rainwater comes from both nitric and sulfuric acids. Compared with contemporary observations at other alpine continental sites in China, the precipitation at Huangshan Mountain was the least polluted, with the lowest ionic concentrations. Trajectories to Huangshan Mountain on rainy days could be classified into six groups. The rainwater with influencing air masses originating in Mongolia was the most polluted with limited effect. The emissions of Jiangxi, Anhui, Zhejiang and Jiangsu provinces had a strong influence on the overall rain chemistry at Huangshan Mountain. The rainwater with influencing air masses from Inner Mongolia was heavily polluted by anthropogenic pollutants.

  5. The patterns and implications of diurnal variations in d-excess of plant water, shallow soil water and air moisture

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Wang, L.; Xiao, H.; Cheng, G.; Ruan, Y.; Zhou, M.; Wang, F.

    2014-04-01

    Deuterium excess (d-excess) of air moisture is traditionally considered as a conservative tracer of oceanic evaporation conditions. Recent studies challenge this view and emphasize the importance of vegetation activity in controlling the dynamics of air moisture d-excess. However direct field observations supporting the role of vegetation in d-excess variations is not well documented. In this study, we quantified d-excess of air moisture, leaf and xylem water of multiple dominant species as well as shallow soil water (5 and 10 cm) at hourly interval during three extensive field campaigns at two climatically different locations within the Heihe River Basin. The results showed that with the increase of temperature (T) and decrease of relative humidity (RH), the δD-δ18O plots of leaf water, xylem water and shallow soil water deviated gradually from their corresponding local meteoric water line. There were significant differences in d-excess values among different water pools at all the study sites. The most positive d-excess values were found in air moisture (9.3‰) and the most negative d-excess values (-85.6‰) were found in leaf water. The d-excess values of air moisture (dmoisture) and leaf water (dleaf) during the sunny days, and shallow soil water (dsoil) during the first sunny day after rain event showed strong diurnal patterns. There were significantly positive relationships between dleaf and RH and negative relationships between dmoisture and RH. The correlations of dleaf and dmoisture with T were opposite to their relationships with RH. In addition, we found the opposite diurnal variations for dleaf and dmoisture during the sunny day, and for dleaf during the sunny days, and shallow soil water dsoil and dmoisture during the first sunny day after rain event. Significant negative relationships were found between dleaf and dmoisture in all the sites during the sunny day. Our results provide direct evidence that dmoisture of the surface air at continental

  6. Concentrations and patterns of polychlorinated naphthalenes in urban air in Beijing, China.

    PubMed

    Xue, Lingnan; Zhang, Lifei; Yan, Yan; Dong, Liang; Huang, Yeru; Li, Xiaoxiu

    2016-11-01

    Air samples were collected, using a high-volume air sampler, at an urban site in Beijing from April 2014 to March 2015. The polychlorinated naphthalene (PCN) concentration in the atmosphere in each season was determined. The total PCN (total target tri- to octachloronaphthalene congeners) concentrations were 1.99-19.0 pg/m(3), and the mean was 7.20 pg/m(3). The PCN concentrations were higher in fall than summer, indicating that the concentrations varied significantly over time. The trichloronaphthalene homolog was the predominant PCN homolog in all four seasons. The PCN toxic equivalent (TEQ) concentrations were 0.42-6.89 fg/m(3), and the mean was 1.74 fg/m(3). The CN-66/67 and CN-73 congeners were the predominant contributors to the TEQ concentrations. The mean seasonal TEQ concentration decreased in the order fall (3.18 fg/m(3)) > winter (1.41 fg/m(3)) > summer (1.11 fg/m(3)) > spring (1.03 fg/m(3)). The TEQ concentrations and the PCN concentrations did not follow the same seasonal trends, but the highest TEQ and PCN concentrations were both found in fall. Correlation analysis, ratio analysis, and principal component analysis were used to investigate the sources of PCNs to the Beijing atmosphere. The results suggested that combustion processes may be the main sources of PCNs to the Beijing atmosphere.

  7. Concentrations and patterns of polychlorinated naphthalenes in urban air in Beijing, China.

    PubMed

    Xue, Lingnan; Zhang, Lifei; Yan, Yan; Dong, Liang; Huang, Yeru; Li, Xiaoxiu

    2016-11-01

    Air samples were collected, using a high-volume air sampler, at an urban site in Beijing from April 2014 to March 2015. The polychlorinated naphthalene (PCN) concentration in the atmosphere in each season was determined. The total PCN (total target tri- to octachloronaphthalene congeners) concentrations were 1.99-19.0 pg/m(3), and the mean was 7.20 pg/m(3). The PCN concentrations were higher in fall than summer, indicating that the concentrations varied significantly over time. The trichloronaphthalene homolog was the predominant PCN homolog in all four seasons. The PCN toxic equivalent (TEQ) concentrations were 0.42-6.89 fg/m(3), and the mean was 1.74 fg/m(3). The CN-66/67 and CN-73 congeners were the predominant contributors to the TEQ concentrations. The mean seasonal TEQ concentration decreased in the order fall (3.18 fg/m(3)) > winter (1.41 fg/m(3)) > summer (1.11 fg/m(3)) > spring (1.03 fg/m(3)). The TEQ concentrations and the PCN concentrations did not follow the same seasonal trends, but the highest TEQ and PCN concentrations were both found in fall. Correlation analysis, ratio analysis, and principal component analysis were used to investigate the sources of PCNs to the Beijing atmosphere. The results suggested that combustion processes may be the main sources of PCNs to the Beijing atmosphere. PMID:27497350

  8. Diurnal variations in the spatial patterns of air pollution across Delhi

    NASA Astrophysics Data System (ADS)

    O'Shea, Patrick M.; Sen Roy, Shouraseni; Singh, R. B.

    2016-05-01

    In the present study, we have analyzed the spatial patterns of seasonal-scale diurnal cycle of three main pollutants, NO2, SO2, and O3, across five stations in Delhi. We used hourly data collected by the local pollution monitoring agencies for the time period, October 2010 to September 2013. Harmonic analysis was used to detect the diurnal cycle in the observed patterns of pollutants across Delhi. The results of our study indicated a consistently higher level of concentrations of all the pollutants at two of the stations, IGI Airport and Civil Lines, while lower concentration levels were observed in the mixed use residential areas of Shadipur and NSIT Dwarka. A clockwise gradual progression in the time of maximum from east to west was observed in the case of SO2 during each season. The time of maximum for O3 for each season was in the early evening hours, 1800 local standard time (LST). Moreover, there were little spatial variations in the peak time of occurrence of NO2 and O3 at the seasonal scale.

  9. Midlatitudes precipitation and the global atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Pauluis, O.; Czaja, A.; Korty, R.; Laliberte, F.

    2008-12-01

    The global atmospheric circulation transports energy from the equatorial regions to higher latitudes. Due to the turbulent nature of the flow, describing a 'mean' circulation depends strongly on the averaging method and coordinates system. When averaged in isentropic coordinates, the circulation appears as a single overturning cell with a poleward flow of high entropy air and return flow at lower entropy. However, the entropy of a parcel of moist air is not uniquely defined, and different expression for the entropy yield different mean circulations. Here, the global circulation in the NCEP/NCAR Reanalysis is computed on surfaces of constant potential temperature, or dry isentropes, and on surfaces of constant equivalent potential temperature, or moist isentropes. The two analyses are qualitatively similar but differ quantitatively in that the circulation on moist isentropes is between 1.5 and 3 times larger than the circulation on dry isentropes. It is shown that the additional mass transport on moist isentropes corresponds to a poleward flow of warm, moist air near the Earth's surface that moves from the subtropics into the midlatitudes and rises in the upper troposphere within the stormtracks. In the subtropics, this flow is characterized by a low potential temperature but a much higher equivalent potential temperature. It does not appear in the circulation on dry isentropes, as it is hidden by the presence of a larger equatorward flow of drier air at same potential temperature. However, as the equivalent potential temperature in this low-level poleward flow is close to the potential temperature of the air near the tropopause, it is included in the total circulation on moist isentropes. The thermodynamic properties of this low-level poleward flow indicates that these poleward moving air parcels should ascend into the upper troposphere within the midlatitude stormtracks. Based on these findings, we propose a revised version of the global circulation. We argue that

  10. Charge and pressure-tuned surface patterning of surfactant-encapsulated polyoxometalate complexes at the air-water interface.

    PubMed

    Xu, Miao; Li, Haolong; Zhang, Liying; Wang, Yizhan; Yuan, Yuan; Zhang, Jianming; Wu, Lixin

    2012-10-16

    In this paper, four organic-inorganic hybrid complexes were prepared using a cationic surfactant dimethyldioctadecylammonium (DODA) to replace the counter cations of four Keggin-type polyoxometalate (POM) clusters with gradually increased negative charges, PW(12)O(40)(3-), SiW(12)O(40)(4-), BW(12)O(40)(5-), and CoW(12)O(40)(6-). The formed surfactant-encapsulated POM (SEP) complexes showed typical amphiphilic properties and can be spread onto the air-water interface to form Langmuir monolayers. The interfacial behavior of the SEP monolayer films was systemically studied by multiple in situ and ex situ characterization methods including Brewster angle microscopy (BAM), atomic force microscopy (AFM), reflection-absorption infrared (RAIR), and X-ray photoelectron spectroscopy (XPS). We found that the increasing alkyl chain density of SEPs leads to an enhanced stability and a higher collapse pressure of SEP Langmuir monolayers. Moreover, a second layer evolved as patterns from the initial monolayers of all the SEPs, when the surface pressures approached the collapse values. The rational combination of alkyl chain density and surface pressure can precisely control the size and the morphology of SEP patterns transforming from disk-like to leaf-like structures on a micrometer scale. The pattern formation was demonstrated to be driven by the self-optimized surface energy of SEP monolayers. This finding can direct a new strategy for the fabrication of POM-hybrid films with controllable patterns, which should be instructive for designing POM-based thin film devices. PMID:22991980

  11. Charge and pressure-tuned surface patterning of surfactant-encapsulated polyoxometalate complexes at the air-water interface.

    PubMed

    Xu, Miao; Li, Haolong; Zhang, Liying; Wang, Yizhan; Yuan, Yuan; Zhang, Jianming; Wu, Lixin

    2012-10-16

    In this paper, four organic-inorganic hybrid complexes were prepared using a cationic surfactant dimethyldioctadecylammonium (DODA) to replace the counter cations of four Keggin-type polyoxometalate (POM) clusters with gradually increased negative charges, PW(12)O(40)(3-), SiW(12)O(40)(4-), BW(12)O(40)(5-), and CoW(12)O(40)(6-). The formed surfactant-encapsulated POM (SEP) complexes showed typical amphiphilic properties and can be spread onto the air-water interface to form Langmuir monolayers. The interfacial behavior of the SEP monolayer films was systemically studied by multiple in situ and ex situ characterization methods including Brewster angle microscopy (BAM), atomic force microscopy (AFM), reflection-absorption infrared (RAIR), and X-ray photoelectron spectroscopy (XPS). We found that the increasing alkyl chain density of SEPs leads to an enhanced stability and a higher collapse pressure of SEP Langmuir monolayers. Moreover, a second layer evolved as patterns from the initial monolayers of all the SEPs, when the surface pressures approached the collapse values. The rational combination of alkyl chain density and surface pressure can precisely control the size and the morphology of SEP patterns transforming from disk-like to leaf-like structures on a micrometer scale. The pattern formation was demonstrated to be driven by the self-optimized surface energy of SEP monolayers. This finding can direct a new strategy for the fabrication of POM-hybrid films with controllable patterns, which should be instructive for designing POM-based thin film devices.

  12. Phases, line tension and pattern formation in molecularly thin films at the air-water interface

    NASA Astrophysics Data System (ADS)

    Mandal, Pritam

    A Langmuir film, which is a molecularly thin insoluble film on a liquid substrate, is one practical realization of a quasi-two dimensional matter. The major advantages of this system for the study of phase separation and phase co-existence are (a) it allows accurate control of the components and molecular area of the film and (b) it can be studied by various methods that require very flat films. Phase separation in molecularly thin films plays an important role in a range of systems from biomembranes to biosensors. For example, phase-separated lipid nano-domains in biomembranes are thought to play crucial roles in membrane function. I use Brewster Angel Microscopy (BAM) coupled with Fluorescence Microscopy (FM) and static Light Scattering Microscopy (LSM) to image phases and patterns within Langmuir films. The three microscopic techniques --- BAM, FM and LSM --- are complimentary to each other, providing distinct sets of information. They allow direct comparison with literature results in lipid systems. I have quantitatively validated the use of detailed hydrodynamic simulations to determine line tension in monolayers. Line tension decreases as temperature rises. This decrease gives us information on the entropy associated with the line, and thus about line structure. I carefully consider the thermodynamics of line energy and entropy to make this connection. In the longer run, LSM will be exploited to give us further information about line structure. I have also extended the technique by testing it on domains within the curved surface of a bilayer vesicle. I also note that in the same way that the presence of surface-active agents, known as surfactants, affects surface energy, the addiction of line active agents alters the inter-phase line energy. Thus my results set to stage to systematically study the influence of line active agents ---'linactants' --- on the inter-phase line energy. Hierarchal self-assembled chiral patterns were observed as a function of

  13. Application of XAD-resin based passive air samplers to assess local (roadside) and regional patterns of persistent organic pollutants.

    PubMed

    Barthel, Paul; Thuens, Sabine; Shunthirasingham, Chubashini; Westgate, John N; Wania, Frank; Radke, Michael

    2012-07-01

    We used XAD-resin based passive air samplers (PAS) to measure atmospheric levels of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) at five ombrotrophic bogs in Eastern Canada. The aims of our study were to investigate the influence of local roads on contaminant levels in the bogs, to derive the regional pattern of atmospheric concentrations, and to assess the uncertainties of the method. Expanded uncertainties based on the duplicate PAS deployed at 24 sites were good for the PAHs, while the deployment period of approx. 100 days was too short to yield acceptable uncertainties for PCBs. The regional PAH distribution was in good agreement with the calculated source proximity of the sampled bogs. We conclude that XAD-resin based PAS deployed for comparatively short periods are well suited for measuring atmospheric concentrations of volatile PAHs, while in remote regions longer deployment is necessary for less volatile PAHs and for PCBs. PMID:22516712

  14. Appearance of target pattern and spiral flames in radial microchannels with CH4-air mixtures

    NASA Astrophysics Data System (ADS)

    Kumar, Sudarshan; Maruta, Kaoru; Minaev, S.; Fursenko, R.

    2008-02-01

    This paper presents the experimental evidence of the formation of rotating spiral flames with premixed methane-air mixtures introduced at the center of the two parallel circular quartz plates which are separated by a millimeter scale distance (≤5mm). Both plates are externally heated to create a positive wall temperature gradient in the flow direction to resemble heat recirculation through solid walls, which is a requisite to obtain stabilized combustion in microburners. Contrary to the general perception of a stable premixed flame front at a radial location, a variety of nonstationary flame propagation modes are observed. For lower mixture flow rates and a range of mixture equivalence ratios, a radial flame propagation mode is observed with simultaneous presence of two circular flames at different radial locations. For higher flow rates, a rotating spiral flame propagation mode is observed. In addition to radial and spiral flame propagation modes, random and unsymmetrical flame oscillations are also observed. The rotational rates of the spiral flame fronts were observed to vary from 28 to 83Hz. A simple analysis is carried out to describe the formation of spiral flames from a steady circular flame.

  15. Non-equilibrium magnetic colloidal dispersions at liquid-air interfaces: dynamic patterns, magnetic order and self-assembled swimmers.

    PubMed

    Snezhko, Alexey

    2011-04-20

    Colloidal dispersions of interacting particles subjected to an external periodic forcing often develop nontrivial self-assembled patterns and complex collective behavior. A fundamental issue is how collective ordering in such non-equilibrium systems arises from the dynamics of discrete interacting components. In addition, from a practical viewpoint, by working in regimes far from equilibrium new self-organized structures which are generally not available through equilibrium thermodynamics can be created. In this review spontaneous self-assembly phenomena in magnetic colloidal dispersions suspended at liquid-air interfaces and driven out of equilibrium by an alternating magnetic field are presented. Experiments reveal a new type of nontrivially ordered self-assembled structures emerging in such systems in a certain range of excitation parameters. These dynamic structures emerge as a result of the competition between magnetic and hydrodynamic forces and have complex unconventional magnetic ordering. Nontrivial self-induced hydrodynamic fields accompany each out-of-equilibrium pattern. Spontaneous symmetry breaking of the self-induced surface flows leading to a formation of self-propelled microstructures has been discovered. Some features of the self-localized structures can be understood in the framework of the amplitude equation (Ginzburg-Landau type equation) for parametric waves coupled to the conservation law equation describing the evolution of the magnetic particle density and the Navier-Stokes equation for hydrodynamic flows. To understand the fundamental microscopic mechanisms governing self-assembly processes in magnetic colloidal dispersions at liquid-air interfaces a first-principle model for a non-equilibrium self-assembly is presented. The latter model allows us to capture in detail the entire process of out-of-equilibrium self-assembly in the system and reproduces most of the observed phenomenology.

  16. Spatial patterns of air pollutants and social groups: a distributive environmental justice study in the phoenix metropolitan region of USA

    NASA Astrophysics Data System (ADS)

    Pope, Ronald; Wu, Jianguo; Boone, Christopher

    2016-11-01

    Quantifying spatial distribution patterns of air pollutants is imperative to understand environmental justice issues. Here we present a landscape-based hierarchical approach in which air pollution variables are regressed against population demographics on multiple spatiotemporal scales. Using this approach, we investigated the potential problem of distributive environmental justice in the Phoenix metropolitan region, focusing on ambient ozone and particulate matter. Pollution surfaces (maps) are evaluated against the demographics of class, age, race (African American, Native American), and ethnicity (Hispanic). A hierarchical multiple regression method is used to detect distributive environmental justice relationships. Our results show that significant relationships exist between the dependent and independent variables, signifying possible environmental inequity. Although changing spatiotemporal scales only altered the overall direction of these relationships in a few instances, it did cause the relationship to become nonsignificant in many cases. Several consistent patterns emerged: people aged 17 and under were significant predictors for ambient ozone and particulate matter, but people 65 and older were only predictors for ambient particulate matter. African Americans were strong predictors for ambient particulate matter, while Native Americans were strong predictors for ambient ozone. Hispanics had a strong negative correlation with ambient ozone, but a less consistent positive relationship with ambient particulate matter. Given the legacy conditions endured by minority racial and ethnic groups, and the relative lack of mobility of all the groups, our findings suggest the existence of environmental inequities in the Phoenix metropolitan region. The methodology developed in this study is generalizable with other pollutants to provide a multi-scaled perspective of environmental justice issues.

  17. Effects of air-exposure gradients on spatial infection patterns of Perkinsus marinus in the eastern oyster Crassostrea virginica.

    PubMed

    Malek, Jennafer C; Breitburg, Denise L

    2016-02-25

    Spatial distributions of species can be shaped by factors such as parasites, mortality, and reproduction, all of which may be influenced by differences in physical factors along environmental gradients. In nearshore tidal waters, an elevational gradient in aerial exposure during low tide can shape the spatial distributions of benthic marine organisms. The eastern oyster Crassostrea virginica is an ecologically and economically important species that can dominate both subtidal and intertidal habitats along the east coast of the USA. Our goal was to determine whether prevalence and intensity of Perkinsus marinus (the causative agent of Dermo disease) infections vary along intertidal to subtidal gradients during summer. We used (1) field experiments conducted at 4 sites in the Chesapeake Bay and a Virginia coastal bay, (2) a controlled air-exposure experiment, and (3) field surveys from 7 sites ranging from Maine to North Carolina to test for effects of tidal exposure on infection. Results from our field surveys suggested that high intertidal oysters tend to have higher infection prevalence than subtidal oysters, but there was no effect on infection intensity. Field experiments rarely yielded significant effects of tidal exposure on infection prevalence and intensity. Overall, our study shows that exposure to air may not be a strong driver of infection patterns in this host-parasite system.

  18. Effects of air-exposure gradients on spatial infection patterns of Perkinsus marinus in the eastern oyster Crassostrea virginica.

    PubMed

    Malek, Jennafer C; Breitburg, Denise L

    2016-02-25

    Spatial distributions of species can be shaped by factors such as parasites, mortality, and reproduction, all of which may be influenced by differences in physical factors along environmental gradients. In nearshore tidal waters, an elevational gradient in aerial exposure during low tide can shape the spatial distributions of benthic marine organisms. The eastern oyster Crassostrea virginica is an ecologically and economically important species that can dominate both subtidal and intertidal habitats along the east coast of the USA. Our goal was to determine whether prevalence and intensity of Perkinsus marinus (the causative agent of Dermo disease) infections vary along intertidal to subtidal gradients during summer. We used (1) field experiments conducted at 4 sites in the Chesapeake Bay and a Virginia coastal bay, (2) a controlled air-exposure experiment, and (3) field surveys from 7 sites ranging from Maine to North Carolina to test for effects of tidal exposure on infection. Results from our field surveys suggested that high intertidal oysters tend to have higher infection prevalence than subtidal oysters, but there was no effect on infection intensity. Field experiments rarely yielded significant effects of tidal exposure on infection prevalence and intensity. Overall, our study shows that exposure to air may not be a strong driver of infection patterns in this host-parasite system. PMID:26912044

  19. Arctic circulation regimes.

    PubMed

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  20. Arctic circulation regimes

    PubMed Central

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L.

    2015-01-01

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  1. Atmospheric circulation classification comparison based on wildfires in Portugal

    NASA Astrophysics Data System (ADS)

    Pereira, M. G.; Trigo, R. M.

    2009-04-01

    Atmospheric circulation classifications are not a simple description of atmospheric states but a tool to understand and interpret the atmospheric processes and to model the relation between atmospheric circulation and surface climate and other related variables (Radan Huth et al., 2008). Classifications were initially developed with weather forecasting purposes, however with the progress in computer processing capability, new and more robust objective methods were developed and applied to large datasets prompting atmospheric circulation classification methods to one of the most important fields in synoptic and statistical climatology. Classification studies have been extensively used in climate change studies (e.g. reconstructed past climates, recent observed changes and future climates), in bioclimatological research (e.g. relating human mortality to climatic factors) and in a wide variety of synoptic climatological applications (e.g. comparison between datasets, air pollution, snow avalanches, wine quality, fish captures and forest fires). Likewise, atmospheric circulation classifications are important for the study of the role of weather in wildfire occurrence in Portugal because the daily synoptic variability is the most important driver of local weather conditions (Pereira et al., 2005). In particular, the objective classification scheme developed by Trigo and DaCamara (2000) to classify the atmospheric circulation affecting Portugal have proved to be quite useful in discriminating the occurrence and development of wildfires as well as the distribution over Portugal of surface climatic variables with impact in wildfire activity such as maximum and minimum temperature and precipitation. This work aims to present: (i) an overview the existing circulation classification for the Iberian Peninsula, and (ii) the results of a comparison study between these atmospheric circulation classifications based on its relation with wildfires and relevant meteorological

  2. Emerging patterns in intercontinental air linkages and implications for international route allocation policy

    SciTech Connect

    Oum, Tae Hoon; Taylor, A.J.

    1995-12-31

    The effects of deregulation, or liberalization of the domestic airline market, in the US, Canada, Australia, New Zealand, and Europe have been described by many authors. It is generally acknowledged that deregulation fostored airline efficiency through the formation of domestic hub-and-spoke networks and established market conditions that encouraged the emergence of the mega-carriers (United, American, and Delta Airlines). Predictions have been made that similar effects will be observed in the intercontinental markets as liberalization is extended to these markets, and that globalized service networks will appear through strong alliances between major carriers based on different continents. These global service networks will be created by linking up the continental hubs of the partners` networks, in order to provide frequent and efficient services. A nation may be able to influence the formation of the global networks through the appropriate selection of policies for the industry structure and international route allocation. Sections of this paper review the important features of the imminent globalization of airline networks, and describe the emerging patterns of intercontinental linkages being adopted by some major carriers in the US and Europe. Later, alternative route allocation policies are defined, and the policies being followed by the US, Japan, Canada, and Korea are analyzed.

  3. Slow and Steady: Ocean Circulation. The Influence of Sea Surface Height on Ocean Currents

    NASA Technical Reports Server (NTRS)

    Haekkinen, Sirpa

    2000-01-01

    The study of ocean circulation is vital to understanding how our climate works. The movement of the ocean is closely linked to the progression of atmospheric motion. Winds close to sea level add momentum to ocean surface currents. At the same time, heat that is stored and transported by the ocean warms the atmosphere above and alters air pressure distribution. Therefore, any attempt to model climate variation accurately must include reliable calculations of ocean circulation. Unlike movement of the atmosphere, movement of the ocean's waters takes place mostly near the surface. The major patterns of surface circulation form gigantic circular cells known as gyres. They are categorized according to their general location-equatorial, subtropical, subpolar, and polar-and may run across an entire ocean. The smaller-scale cell of ocean circulation is known' as an eddy. Eddies are much more common than gyres and much more difficult to track in computer simulations of ocean currents.

  4. Demonstration of an advanced circulation fludized bed coal combustor phase 1: Cold model study. Final report

    SciTech Connect

    Govind, R.

    1993-03-20

    It was found that there was a strong dependence of the density profile on the secondary air injection location and that there was a pronounced solid separation from the conveying gas, due to the swirl motion. Furthermore, the swirl motion generated strong internal circulation patterns and higher slip velocities than in the case of nonswirl motion as in an ordinary circulating fluidized bed. Radial solids flux profiles were measured at different axial locations. The general radial profile in a swirling circulating fluidized bed indicated an increased downward flow of solids near the bed walls, and strong variations in radial profiles along the axial height. For swirl numbers less than 0.9, which is typical for swirling circulating fluidized beds, there is no significant increase in erosion due to swirl motion inside the bed. Pending further investigation of swirl motion with combustion, at least from our cold model studies, no disadvantages due to the introduction of swirl motion were discovered.

  5. Forecasting for New York City and its Surroundings, with Emphasis on Sea-Surface Temperature's Effect on Sea Breezes and Other Coastal Circulations that Influence Air Quality

    NASA Astrophysics Data System (ADS)

    Knievel, J. C.; Rife, D. L.; Grim, J. A.

    2008-12-01

    The complex coastal setting of New York City, Long Island, and the surrounding urban environment affects boundary-layer winds and the way they transport hazardous airborne materials, including pollutants. Properly forecasting coastal circulations, such as sea breezes, is critical if weather-based decision support systems (DSSs) are to be useful to health officials, emergency responders, and anyone else interested in the challenges of predicting transport and dispersion in urban settings. The Research Applications Laboratory (RAL) within the National Center for Atmospheric Research (NCAR) is running a real-time forecast system focused on New York City (NYC) and its urban and suburban surroundings. The system is based on the Weather Research and Forecasting (WRF) Model and NCAR's Real-Time Four-Dimensional Data Assimilation (RTFDDA) System. The presenter will provide an overview of the project and present results from a few case studies of sea breezes and other circulations characteristic of the complex coastal setting of NYC and Long Island. A particular emphasis of the presentation will be the sensitivity of forecasts to sea-surface temperature (SST). The forecast system is currently using SSTs from gridded composites created by NCAR from observations by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua and Terra satellites.

  6. Slowdown of the Walker circulation driven by tropical Indo-Pacific warming.

    PubMed

    Tokinaga, Hiroki; Xie, Shang-Ping; Deser, Clara; Kosaka, Yu; Okumura, Yuko M

    2012-11-15

    Global mean sea surface temperature (SST) has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of SST warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes.

  7. Slowdown of the Walker circulation driven by tropical Indo-Pacific warming.

    PubMed

    Tokinaga, Hiroki; Xie, Shang-Ping; Deser, Clara; Kosaka, Yu; Okumura, Yuko M

    2012-11-15

    Global mean sea surface temperature (SST) has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of SST warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes. PMID:23151588

  8. NEIGHBORHOOD SCALE AIR QUALITY MODELING IN HOUSTON USING URBAN CANOPY PARAMETERS IN MM5 AND CMAQ WITH IMPROVED CHARACTERIZATION OF MESOSCALE LAKE-LAND BREEZE CIRCULATION

    EPA Science Inventory

    Advanced capability of air quality simulation models towards accurate performance at finer scales will be needed for such models to serve as tools for performing exposure and risk assessments in urban areas. It is recognized that the impact of urban features such as street and t...

  9. Fluid circulation pattern inside La Soufrière volcano (Guadeloupe) inferred from combined electrical resistivity tomography, self-potential, soil temperature and diffuse degassing measurements

    NASA Astrophysics Data System (ADS)

    Brothelande, E.; Finizola, A.; Peltier, A.; Delcher, E.; Komorowski, J.-C.; Di Gangi, F.; Borgogno, G.; Passarella, M.; Trovato, C.; Legendre, Y.

    2014-11-01

    After a drastic decline in 1983, hydrothermal activity at La Soufrière lava dome (Guadeloupe, Lesser Antilles) has been progressively increasing in the summit area since 1992, raising the threat of a renewed eruptive activity. To better constrain the geometry of the hydrothermal system, an extensive high-resolution self-potential survey was performed on the dome and three multi-method profiles combining electrical resistivity tomography, self-potential, ground thermometry and soil CO2 diffuse degassing measurements were carried out to cover its southern periphery in January 2011. Results indicate that hydrothermal ascending flows are currently restricted to a proximal area including the dome and its very vicinity. The extension of hydrothermal alteration inferred from electrical resistivity tomography reflects the presence of a heat source just below the dome. A first-order correction of topography-related self-potential variations allows the identification of major hydrothermal fluid circulations pathways, as well as significant meteoric infiltration zones. Local shifting of hydrothermal fluids towards the dome periphery is favored by the presence of major axes. The regional La Ty fault appears as the major axis draining large volumes of hydrothermal and magmatic fluids. However hydrothermal activity remains confined inside a collapse structure surrounding the dome, that formed in the last 9000 years as a result of recurrent edifice collapses, the latest occurring at the onset of the 1530 AD eruption. The combination of these qualitative results with structural analysis leads to a synthetic model of magmatic and hydrothermal fluids circulation inside the dome, which may be useful for the assessment of potential hazards associated with a renewal of fluid pressurization, and a possibly associated partial flank-failure.

  10. Three port optical circulators with ring resonators

    NASA Astrophysics Data System (ADS)

    Jalas, Dirk; Petrov, Alexander Y.; Eich, Manfred

    2014-05-01

    We present a concept for a circulator that has the same bandwidth efficiency as a photonic crystal circulator but which relies on a ring resonator and thereby is experimentally much easier to realize. We achieve this by side coupling three waveguides to the ring resonator. The desired standing wave pattern which recreates the photonic crystal type circulator spectrum is realized by exciting both the clockwise and counter-clockwise traveling wave through a Bragg reflector.

  11. Gene expression patterns through oral squamous cell carcinoma development: PD-L1 expression in primary tumor and circulating tumor cells.

    PubMed

    Oliveira-Costa, Joao Paulo; de Carvalho, Alex Fiorini; da Silveira, da Giorgia Gobbi; Amaya, Peter; Wu, Yongqi; Park, Kyoung-Joo Jenny; Gigliola, Mabel Pinilla; Lustberg, Maryam; Buim, Marcilei Eliza Cavicchioli; Ferreira, Elisa Napolitano; Kowalski, Luiz Paulo; Chalmers, Jeffrey J; Soares, Fernando Augusto; Carraro, Dirce Maria; Ribeiro-Silva, Alfredo

    2015-08-28

    Oral squamous cell carcinoma (OSCC) is the most common tumor of the oral cavity and has been associated with poor prognosis. Scarce prognostic markers are available for guiding treatment and/or sub-classifying patients. This study aims to identify biomarkers by searching for genes whose expression is increased or decreased during tumor progression (through T1 to T4 stages). Thirty-six samples from all tumor size stages (from T1 to T4) were analyzed using cDNA microarrays. Selected targets were analyzed by immunohistochemistry and in circulating tumor cells by immunofluorescence and Nanostring. Correlation was shown between PD-L1 and tumor size and lymph node metastasis, HOXB9 and tumor size, BLNK and perineural invasion, and between ZNF813 and perineural invasion. PD-L1 positivity was an independent prognostic factor in this cohort (p = 0.044, HH = 0.426). In CTCs from patients with locally advanced OSCC, we found a strong cytoplasmatic expression of PD-L1. PD-L1 is a ligand of PD-1 and is believed to limit T cell activity in inflammatory responses and limit autoimmune diseases. We demonstrated an important role for PD-L1 in primary tumors according to tumor size, and in disease specific survival. Therefore, we could further determine individuals with PD-L1+ CTCs, and possibly follow treatment using CTCs. PMID:26041877

  12. Gene expression patterns through oral squamous cell carcinoma development: PD-L1 expression in primary tumor and circulating tumor cells

    PubMed Central

    Oliveira-Costa, Joao Paulo; de Carvalho, Alex Fiorini; da Silveira, Giorgia Gobbi; Amaya, Peter; Wu, Yongqi; Park, Kyoung-Joo Jenny; Gigliola, Mabel Pinilla; Lustberg, Maryam; Buim, Marcilei Eliza Cavicchioli; Ferreira, Elisa Napolitano; Kowalski, Luiz Paulo; Chalmers, Jeffrey J.; Soares, Fernando Augusto; Carraro, Dirce Maria; Ribeiro-Silva, Alfredo

    2015-01-01

    Oral squamous cell carcinoma (OSCC) is the most common tumor of the oral cavity and has been associated with poor prognosis. Scarce prognostic markers are available for guiding treatment and/or sub-classifying patients. This study aims to identify biomarkers by searching for genes whose expression is increased or decreased during tumor progression (through T1 to T4 stages). Thirty-six samples from all tumor size stages (from T1 to T4) were analyzed using cDNA microarrays. Selected targets were analyzed by immunohistochemistry and in circulating tumor cells by immunofluorescence and Nanostring. Correlation was shown between PD-L1 and tumor size and lymph node metastasis, HOXB9 and tumor size, BLNK and perineural invasion, and between ZNF813 and perineural invasion. PD-L1 positivity was an independent prognostic factor in this cohort (p = 0.044, HH = 0.426). In CTCs from patients with locally advanced OSCC, we found a strong cytoplasmatic expression of PD-L1. PD-L1 is a ligand of PD-1 and is believed to limit T cell activity in inflammatory responses and limit autoimmune diseases. We demonstrated an important role for PD-L1 in primary tumors according to tumor size, and in disease specific survival. Therefore, we could further determine individuals with PD-L1+ CTCs, and possibly follow treatment using CTCs. PMID:26041877

  13. Long-range transport and re-circulation of pollutants in the western Mediterranean during the project Regional Cycles of Air Pollution in the West-Central Mediterranean Area

    NASA Astrophysics Data System (ADS)

    Gangoiti, Gotzon; Millán, Millán M.; Salvador, Rosa; Mantilla, Enrique

    During the warm season (March-September), high ozone concentrations have been reported at the coastal and mountain monitoring stations of the eastern Iberia coast (Millán et al., J. Geophys. Res. 102 (D7) 8811, J. Appl. Meteorol. 4 (2000) 487). The vegetation protection threshold of current Directive 92/72/EEC and the World Health Organisation guideline for the protection of crops and semi-natural vegetation are systematically exceeded during the whole period. The main objective of the present study is to search for the origin of these chronic pollution levels: to search for the reason(s) for such high O 3 concentrations during such a long period. A mesoscale model is used to reproduce the diurnal cycle of winds and stability/layering over the Western Mediterranean Basin (WMB), at a sufficient space/temporal resolution, under a typical recursive synoptic condition during the warm season: data from the flight tracks of the European Project—Regional Cycles of Air Pollution in the West-Central Mediterranean Area—are used to substantiate the model results. Times of residence and the final distribution of pollutants entering the WMB are estimated using single-particle Lagrangian trajectories and a multiple-particle dispersion model. Our results show that the marine boundary layer and the lower troposphere in the region between the Balearic Islands and eastern Iberia are subject to a flow regime that tends to accumulate pollutants within large circulations, covering the entire western basin. We have also shown a diurnal pulsation of the Tramontana/Mistral wind regime, which can transport new pollutants into the area (background concentrations of 50-65 ppb of O 3 of continental European origin) that are added to local emissions and re-circulated within the coastal breezes at eastern Iberia for periods of more than five days. Local emissions and wind configuration contribute to increase the O 3 concentrations up to 100 ppb and even more.

  14. Study of a cave's air exchange pattern based on radon concentration and the time dependence of radon concentration in Pál-völgy Cave (Budapest, Hungary)

    NASA Astrophysics Data System (ADS)

    Nagy, H. E.; Horvath, A.; Jordan, Gy.; Szabo, Cs.; Kiss, A.

    2012-04-01

    A long-term (one year and a half), high resolution, with an integration time of one hour, radon concentration monitoring was carried out in Pál-völgy Cave (Budapest, Hungary). Our major goal was to determine the time dependence of radon concentration in the cave and to understand the exchange pattern of the cave air with the outdoor air based on radon concentrations, and to determine the factors that affect the radon concentration in the cave air. Pál-völgy Cave is situated in the Buda Hills, which is the NE part of the Transdanubian Central Range. The wall rock of the cave is dominantly Eocene Szépvölgy Limestone Formation. Above the limestone Eocene Buda Marl and Oligocene Tard Clay are deposited. A huge multiphase hydrothermal cave system developed in the Szépvölgy Limestone and partially in the Buda Marl resulted in a long-term complex paleokarstic evolution from the Late Eocene to the Quaternary. The radon concentration in the cave air was measured continuously by an AlphaGuard radon monitor, and meteorological parameters outside the cave were also collected simultaneously. The arithmetic mean of the annual radon concentration was 1.9 kBq/m3 and the radon concentration varied between 104-7,776 Bq/m3. In addition, the results indicate a clear seasonal variability of radon concentration in the cave air: in winter the radon concentration fluctuates around a low mean value of 253 Bq/m3, in summer it oscillates around a high mean value of 5,504 Bq/m3, whereas in spring and autumn the radon level varies between the winter and summer values. The summer to winter radon concentration ratio (radon concentration in summer/radon concentration in winter) was high, 21.8. The outside air temperature showed the strongest correlation with the radon concentration in the cave, Pierson's linear correlation coefficient is 0.76. If the outdoor air temperature is lower than the cave air temperature (12 °C), especially in autumn and winter the air flows from outside into the

  15. Stratification and Circulation of the Glacial Ocean: Reconstructing Watermass Geometry and Circulation with Nd Isotopes

    NASA Astrophysics Data System (ADS)

    Piotrowski, A. M.; Goldstein, S. L.; Hemming, S. R.

    2004-12-01

    One of the most important debates in paleoclimate research is the link between ocean circulation and climate change. On glacial-interglacial timescales, global climate is driven by Milankovich orbital cycles, though the resulting insolation variations are small and require amplifying mechanisms. Changes in the strength of global "conveyor-belt" ocean circulation is one possible amplifying mechanism, and abrupt switches between circulation modes may have triggered rapid climate changes. Understanding the ocean-climate link has been difficult because nutrient-based proxies of ocean circulation disagree with each other. During the last glacial period, benthic foraminiferal carbon isotopes suggest substantially weaker North Atlantic Deep Water (NADW) formation and export, while benthic Cd/Ca indicate a strong flow of North Atlantic -sourced water at intermediate depths. Non-circulatory effects (including fractionation during calcite dissolution, changes in global carbon budget, air-sea gas equilibration, and porewater effects) are known to overprint these proxies, likely causing this discrepancy. Neodymium isotopes can resolve this disagreement because it does not share the same sources of error as nutrient-based proxies. We report Nd isotopes measured on Fe-Mn leaches from sites located throughout the South Atlantic. These sites range in depth from 2000 - 5000 mbsl, allowing a three-dimensional perspective of South Atlantic watermass geometry. The leachates have marine Sr isotopic composition. Coretop samples have Nd isotopic compositions which match overlying bottom waters. This coretop calibration is consistent with known vertical and horizontal geometry of NADW and Antarctic Bottom Water. Samples from the last glacial maximum show a coherent glacial-interglacial pattern of circulation change which is most simply interpreted as indicating a reduction in the amount of NADW reaching the South Atlantic. The relative contribution of NADW to the glacial South Atlantic

  16. Sea surface temperature and salinity patterns in the northern North Atlantic and the Arctic during interglacial MIS 11c: Implications for oceanic circulation reconstruction

    NASA Astrophysics Data System (ADS)

    Kandiano, E.; van der Meer, M.; Schouten, S.; Fahl, K.; Polyak, L. V.; Cronin, T. M.; Bauch, H. A.; Sinninghe Damste, J. S.

    2013-12-01

    Sea surface temperature (SST) patterns in the northern North Atlantic, the Nordic seas, and the western Arctic Ocean (AO) were reconstructed across the MIS 11c interglacial, a potential future climate analogue, using planktic foraminiferal abundances, alkenone-based Uk'37 and glycerol dialkyl glycerol tetraether (GDGT)-based TEX86 analyses. Foraminiferal SST reconstructions were supported by foraminiferal counts of small-sized fractions and rare foraminiferal species, stable oxygen isotope measurements on benthic and planktic foraminifers, and ice rafted debris records. Additionally, the hydrogen isotopic (δD) compositions of long chain alkenones were determined to assess variations in paleo sea surface salinity in the North Atlantic. In the North Atlantic our newly produced TEX86 -based SSTs range between 14 and 19 °C in agreement with summer foraminiferal SST (13 and 18 °C) and alkenone SSTs (13 and 16 °C). However, the former showed higher fluctuations than SSTs based on foraminiferal abundances. In concordance with δ18O records TEX86 SSTs demonstrate notable variability in the middle of MIS 11c, between 400 and 410 ka, which is consistent with the intra-MIS 11c cold event in the Arctic indicated by planktic foraminifers. This pattern implies that the interglacial MIC 11c climate was probably not as stable as it widely believed. The preliminary alkenone δD data show that during MIS 11c salinity values in the North Atlantic were similar to Holocene values. Foraminiferal SST records imply that during MIS 11c at least parts of the AO experienced unusually warm and probably ice free conditions, whereas the Nordic seas remained rather cold, especially during the early phase of this period, as it is inferred from foraminiferal and alkenone SSTs. At the same time all our SST records show that the North Atlantic was 1-2°C warmer than present during MIS 11c. This pattern suggests that during MIS 11c the North Atlantic Current was deflected to the west, which

  17. Equatorial zonal circulations: Historical perspectives

    NASA Astrophysics Data System (ADS)

    Hastenrath, Stefan

    2007-04-01

    The changing perceptions on zonal circulations in the equatorial belt are traced for (a) stratospheric wind regimes, and (b) vertical-zonal circulation cells in the troposphere. (a) Observations from the Krakatoa eruption 1883 and Berson's 1908 expedition to East Africa, along with later soundings over Batavia (Jakarta) led to the notion of "Krakatoa easterlies" around 30 km (10 mb) and "Berson westerlies" around 20 km (50 mb). Prompted by contrary observations since the late 1950s, this dogma was replaced by the notion of easterlies alternating with westerlies in the equatorial stratosphere at a rhythm of about 26 months. (b) Stimulated by Bjerknes' postulate of a "Walker circulation" along the Pacific Equator, a multitude of such cells have been hypothesized at other longitudes, in part from zonal contrasts of temperature and cloudiness. Essential for the diagnosis of equatorial zonal circulation cells is the continuity following the flow between the centers of ascending and subsiding motion. Evaluation of the recent NCEP-NCAR and ECMWF Reanalysis upper-air datasets reveals equatorial zonal circulation cells over the Pacific all year round, over the Atlantic only in boreal winter, and over the Indian Ocean only in autumn, all being seasons and oceanic longitudes with strong zonal flow in the lower troposphere.

  18. Air conditioned suit

    NASA Technical Reports Server (NTRS)

    Carl, G. R. (Inventor)

    1973-01-01

    An environmentally controlled suit is described consisting of an airtight outergarment attached by an airtight bellows to the wall of a sterile chamber, an undergarment providing for circulation of air near the skin of the wearer, and a circulation system comprised of air supply and distribution to the extremities of the undegarment and central collection and exhaust of air from the midsection of the undergarment. A workman wearing the undergarment and attached circulation system enters the outer garment through a tunnel in the chamber wall and the attached bellows to work in the chamber without any danger of spreading bacteria.

  19. Exploring EKC, trends of growth patterns and air pollutants concentration level in Malaysia: A Nemerow Index Approach

    NASA Astrophysics Data System (ADS)

    Bekhet, Hussain A.; >Tahira Yasmin,

    2013-06-01

    The present study examines an Environmental Kuznets Curve (EKC) hypothesis by analyzing annual data of air pollutants concentartion and per capita GDP as economic indicator over the (1996-2010) period in Malaysia. Nemerow Index Approach (I) used to generate a measures of air pollution. The results show that ambient air quality indicators supports the EKC hypothesis which stated that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning poin. Also, the I result is justifying that most pollutants are showing value less than 1.

  20. Control of a Circulating Fluidized Bed

    SciTech Connect

    Shim, Hoowang; Rickards, Gretchen; Famouri, Parviz; Turton, Richard; Sams, W. Neal; Koduro, Praveen; Patankar, Amol; Davari, Assad; Lawson, Larry; Boyle, Edward J.

    2001-11-06

    Two methods for optimally controlling the operation of a circulating fluidized bed are being investigated, neural network control and Kalman filter control. The neural network controls the solids circulation rate by adjusting the flow of move air in the non-mechanical valve. Presented is the method of training the neural network from data generated by the circulating fluidized bed (CFB), the results of a sensitivity study indicating that adjusting the move air can control solids flow, and the results of controlling solids circulation rate. The Kalman filter approach uses a dynamic model and a measurement model of the standpipe section of the CFB. Presented are results showing that a Kalman filter can successfully find the standpipe bed height.

  1. [Spatiotempaoral distribution patterns of photosynthetic photon flux density, air temperature, and relative air humidity in forest gap of Pinus koraiensis-dominated broadleaved mixed forest in Xi-ao Xing' an Mountains].

    PubMed

    Li, Meng; Duan, Wen-biao; Chen, Li-xin

    2009-12-01

    A continuous measurement of photosynthetic photon flux density (PPFD), air temperature, and relative air humidity was made in the forest gap in primary Pinus koraiensis-dominated broadleaved mixed forest in Xiao Xing' an Mountains to compare the spatiotemporal distribution patterns of the parameters. The diurnal maximum PPFD in the forest gap appeared between 11:00 and 13:00 on sunny and overcast days. On sunny days, the maximum PPFD during various time periods did not locate in fixed locations, the diurnal maximum PPFD occurred in the canopy edge of northern part of the gap; while on overcast days, it always occurred in the center of the gap. The mean monthly PPFD in the gap was the highest in June and the lowest in September, with the largest range observed in July. The maximum air temperature happened between 9:00 and 15:00 on sunny days, between 15:00 and 19:00 on overcast days, the locations were 8 m in the southern part of gap center both on sunny and overcast days. From 5:00 to 9:00, the air temperature at measured positions in the gap was higher on overcast days than on sunny days; but from 9:00 to 19:00, it was opposite. The mean monthly air temperature was the highest in June, and the lowest in September. The maximum relative humidity appeared between 5:00 and 9:00 on sunny and overcast days, and occurred in the canopy border of western part of the gap, with the relative air humidity on overcast days being always higher than that on sunny days. The mean monthly relative humidity was the highest in July, and the lowest in June. The heterogeneity of PPFD was higher on sunny days than on overcast days, but the heterogeneities of air temperature and relative humidity were not obvious. The maximum PPFD, air temperature, and relative humidity were not located in the same positions among different months during growing season. For mean monthly PPFD and air temperature, their variation gradient was higher in and around the center of gap; while for mean monthly

  2. The Hydrothermal Circulation of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Kjellsson, J.; Doos, K.; Laliberté, F. B.; Zika, J. D.

    2012-12-01

    The atmospheric circulation maintains the energy balance between the warm/moist regions and the colder/drier regions of the Earth. A well-studied aspect of the atmospheric circulation is the time-averaged zonal-mean meridional overturning circulation. The meridional overturning describes the Hadley, Ferrel and Polar Cells in each hemisphere. However, in isobaric coordinates, the zonal average is unable to capture zonally asymmetric features such as the Walker circulation and transient exchanges of heat and moisture. The Walker Circulation is restricted to equatorial regions, and is commonly studied using a meridional mean over a limited region with ill-defined latitudinal boundaries. The Walker Circulation is thus neither mass-conserving nor uniquely defined. To overtcome these limitations, the Walker circulation is often diagnosed using vertical velocity. As a consequence, it is difficult to distinguish between the zonal-mean circulation (Hadley Circulation) and the zonal asymmetries (Walker Circulation). Global mass and energy transport is here investigated using a moisture-heat perspective. A hydrothermal streamfunction is defined where latent heat and dry static energy act as coordinates. Because the hydrothermal streamfunction resides in purely thermodynamical space, it does not differentiate between zonal, meridional, or vertical transports. The hydrothermal streamfunction shows the global overturning circulation as a unified cycle. It describes a cycle with three branches: i) a convective branch where latent heat is converted into sensible heat along moist adiabats, ii) a cooling branch where dry air loses energy due to radiative damping and iii) a return branch where cold, dry air is heated and moistened following the Clausius-Clapeyron relationship. These three branches form a single cell of more than 400 Sv with at least 100 Sv due to zonal motions such as the Walker Circulation. The cell is also found fairly stationary on seasonal and inter

  3. Spontaneous change in trajectory patterns of a self-propelled oil droplet at the air-surfactant solution interface

    NASA Astrophysics Data System (ADS)

    Tanaka, Shinpei; Sogabe, Yoshimi; Nakata, Satoshi

    2015-03-01

    Trajectory-pattern formation of a self-propelled oil droplet floating on the surface of a surfactant solution in a circular dish is studied both experimentally and by simulation. The Marangoni effect induced by the dissolution of oil in the solution drives the droplet's motion. The trajectories spontaneously organize into several patterns including circular, knot-forming, back-and-forth, and irregular ones. They are either global patterns, whose center corresponds to the dish center, or other local patterns. Our simple model consisting of three forces, the driving force, the viscous resistance, and the repulsion from the boundary, successfully reproduces the global trajectory patterns including the power spectrum of the droplet speed.

  4. Interdecadal variations of the thermohaline circulation in a coupled ocean-atmosphere model

    SciTech Connect

    Delworth, T.; Manabe, S.; Stouffer, R.J. )

    1993-11-01

    A fully coupled ocean-atmosphere model is shown to have irregular oscillations of the thermohaline circulation in the NOrth Atlantic Ocean with a time scale of approximately 50 years. The irregular oscillation appears to be driven by density anomalies in the sinking region of the thermohaline circulation (approximately 52[degrees]N to 72[degrees]N) combined with much smaller density anomalies of opposite sign in the broad, rising region. The spatial pattern of sea surface temperature anomalies associated with this irregular oscillation bears an encouraging resemblance to a pattern of observed interdecadal variability in the North Atlantic. The anomalies of sea surface temperature induce model surface air temperature anomalies over the northern North Atlantic, Arctic, and northwestern Europe. 21 refs., 28 figs.

  5. Pulsatile administration of gonadotropin-releasing hormone does not alter the follicle-stimulating hormone (FSH) isoform distribution pattern of pituitary or circulating FSH in nutritionally growth-restricted ovariectomized lambs.

    PubMed

    Hassing, J M; Kletter, G B; I'Anson, H; Wood, R I; Beitins, I Z; Foster, D L; Padmanabhan, V

    1993-04-01

    The experimental induction of puberty by GnRH administration to prepubertal lambs increases serum bioactive FSH (B-FSH) as measured in the rat Sertoli cell aromatase induction bioassay. Serum immunoreactive FSH (I-FSH) levels are unchanged. The increase in serum B-FSH is associated with an increase in the proportion of less acidic and more biopotent FSH serum isoforms. However, it is unknown if this effect of GnRH on serum FSH microheterogeneity is direct or mediated by gonadal factors. We have used the nutritionally growth-restricted ovariectomized lamb as a model of the neuroendocrine regulation of FSH isoform microheterogeneity. With this model, the hypothalamic-pituitary component of the neuroendocrine axis may be isolated from gonadal factors. In the present study, using the nutritionally growth-restricted ovariectomized lamb as a model, we investigated the role of GnRH on the regulation of FSH microheterogeneity. Specifically, we tested the hypothesis that GnRH increases the proportion of the less acidic (more biopotent) serum FSH isoforms. As an in vitro correlate, we investigated the effect of GnRH on gonadotropin secretion and FSH isoform distribution in ovine pituitary explant cultures. Seven ovariectomized nutritionally restricted lambs were administered GnRH (i.v., 2 ng/kg) for 36 h (at 2-h intervals for 24 h, then hourly for the final 12 h). Six others served as controls. Blood samples were withdrawn at 12-min intervals during the last 4 h for the measurement of serum immunoactive LH (I-LH) and I-FSH. Pituitary homogenates and serum from four animals from each group were individually chromatofocused, and the FSH isoform distribution patterns were determined. Pulsatile administration of GnRH to nutritionally growth-restricted lambs increased circulating I-LH concentrations from 0.6 +/- 1.0 to 5.9 +/- 3.1 ng/ml (P < 0.01), but did not significantly change circulating I-FSH (4.9 +/- 1.8 vs. 11.5 +/- 4.2 ng/ml) nor B-FSH concentrations (3.9 +/- 1.2 vs. 5

  6. Impact of Stratospheric Ozone Distribution on Features of Tropospheric Circulation

    NASA Astrophysics Data System (ADS)

    Barodka, Siarhei; Krasouski, Aliaksandr; Mitskevich, Yaroslav; Shalamyansky, Arkady

    2016-04-01

    In this work we study connections between stratospheric ozone distribution and general circulation patterns in the troposphere and aim to investigate the causal relationship between them, including the practical side of the influence of stratospheric ozone on tropospheric medium-range weather and regional climate. Analysis of several decades of observational data, which has been performed at the A.I. Voeikov Main Geophysical Observatory, suggests a clear relation between the stratospheric ozone distribution, upper stratospheric temperature field and planetary-scale air-masses boundaries in the troposphere [1]. Furthermore, it has been shown that each global air-mass, which can be attributed to the corresponding circulation cell in a conceptual model of tropospheric general circulation, has a distinct "regime" of ozone vertical distribution in the stratosphere [1-3]. Proceeding from atmospheric reanalyses combined with satellite and ground-based observations, we study time evolution of the upper-level frontal zones (stationary fronts) with the relevant jet streams, which can be treated as boundaries of global air-masses, in connection with the tropopause height and distribution of ozone in the stratosphere. For that, we develop an algorithm for automated identification of jet streams, stationary fronts and tropopause surface from gridded data (reanalyses or modelling results), and apply it for several cases associated with rapid changes in the stratospheric temperature and ozone fields, including SSW events over Eastern Siberia. Aiming to study the causal relationship between the features of tropospheric circulation and changes in the stratospheric ozone field, we estimate the time lag between these categories of processes on different time scales. Finally, we discuss the possibility to use the elementary circulation mechanisms classification (by B.L. Dzerdzeevski) in connection with analysis of the stratospheric ozone field and the relevant stratosphere

  7. MODELING ASSESSMENT OF TRANSPORT AND DEPOSITION PATTERNS OF MERCURY AIR EMISSIONS FROM THE U.S. AND CANADA

    EPA Science Inventory

    In December 1997, the U.S. EPA submitted the Mercury Study Report to Congress which included a regional-scale modeling assessment of the transport and deposition of U.S. air emissions of mercury. This modeling was performed with a modified version of the Regional Lagrangian Mode...

  8. Air circulation under reduced atmospheric pressures

    NASA Astrophysics Data System (ADS)

    Hillhouse, Lendell E.

    The control of heat exchange is vital for plant life in off-world, low pressure, greenhouses. The ability to control this process was limited by methodology and technology. Mathematical models, based on classical mechanics are created to enhance our control capabilities. Data is collected using various sensors placed inside the Low Pressure Test Bed (LPTB) Chamber at Kennedy Space Center. Data from those sensors became non-linear at various pressures below 25 kPa. We introduced mathematical calibration corrections and found that sensor data linearity could be extended to a greater range of pressures. These calibration corrections allow for sensor calibration corrections in operational environments that differ from the environment of calibration (normal Earth atmospheric pressure).

  9. Evaluating the effect of human activity patterns on air pollution exposure using an integrated field-based and agent-based modelling framework

    NASA Astrophysics Data System (ADS)

    Schmitz, Oliver; Beelen, Rob M. J.; de Bakker, Merijn P.; Karssenberg, Derek

    2015-04-01

    Constructing spatio-temporal numerical models to support risk assessment, such as assessing the exposure of humans to air pollution, often requires the integration of field-based and agent-based modelling approaches. Continuous environmental variables such as air pollution are best represented using the field-based approach which considers phenomena as continuous fields having attribute values at all locations. When calculating human exposure to such pollutants it is, however, preferable to consider the population as a set of individuals each with a particular activity pattern. This would allow to account for the spatio-temporal variation in a pollutant along the space-time paths travelled by individuals, determined, for example, by home and work locations, road network, and travel times. Modelling this activity pattern requires an agent-based or individual based modelling approach. In general, field- and agent-based models are constructed with the help of separate software tools, while both approaches should play together in an interacting way and preferably should be combined into one modelling framework, which would allow for efficient and effective implementation of models by domain specialists. To overcome this lack in integrated modelling frameworks, we aim at the development of concepts and software for an integrated field-based and agent-based modelling framework. Concepts merging field- and agent-based modelling were implemented by extending PCRaster (http://www.pcraster.eu), a field-based modelling library implemented in C++, with components for 1) representation of discrete, mobile, agents, 2) spatial networks and algorithms by integrating the NetworkX library (http://networkx.github.io), allowing therefore to calculate e.g. shortest routes or total transport costs between locations, and 3) functions for field-network interactions, allowing to assign field-based attribute values to networks (i.e. as edge weights), such as aggregated or averaged

  10. The role of synoptic-scale circulation in the linkage between large-scale ocean-atmosphere indices and winter surface climate in British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Stahl, Kerstin; Moore, R. Dan; McKendry, Ian G.

    2006-03-01

    In much of North America, variables such as temperature, precipitation, snowpack and streamflow are modulated by modes of large-scale ocean-atmosphere variability such as the Pacific Decadal Oscillation (PDO), El Niño-Southern Oscillation (ENSO) and the Pacific North American Pattern (PNA). In this study, we test the hypothesis that the influence of these modes on air temperature and precipitation in British Columbia (BC), Canada, can be explained in relation to changes in frequencies of synoptic-scale circulation types. A catalogue of 13 circulation types was derived by classifying daily mean sea-level pressure (MSLP) grids from 1948 to 2003. The grids cover BC and the North Pacific and were subjected to a standard pattern recognition algorithm employing principal component analysis followed by cluster analysis on the component scores. The circulation types are generally associated with distinctive patterns of precipitation and air temperature anomalies across BC. Multiple linear regressions for selected stations in BC using the type frequencies as predictors explain up to 75% of the variance of mean winter temperature and 65% of winter precipitation. The frequencies of most circulation types vary significantly between the different phases of ENSO, PDO and PNA in a manner consistent with the temperature anomalies associated with those modes and, to a lesser extent, with the more complex precipitation anomalies. In addition, however, average temperatures and precipitation amounts for some circulation types differ systematically between phases of ENSO and PDO. Subsequent analysis revealed distinct differences among ENSO and PDO phases in the upper-level circulation patterns associated with some surface types. A major part of the teleconnections can be explained through variations in the frequencies of synoptic-scale circulation types, but systematic within-type variability, particularly with PDO and PNA, can additionally influence the surface climate.

  11. Circulation exchange patterns in Sinclair Inlet, Washington

    USGS Publications Warehouse

    Noble, Marlene A.; Rosenberger, Kurt J.; Paulson, Anthony J.; Gartner, Anne L.

    2013-01-01

    In 1994, the U.S. Geological Survey (USGS), in cooperation with the U.S. Navy, deployed three sets of moorings in Sinclair Inlet, which is a relatively small embayment on the western side of Puget Sound (fig. 1). This inlet is home to the Puget Sound Naval Shipyard. One purpose of the measurement program was to determine the transport pathways and fate of contaminants known to be present in Sinclair Inlet. Extensive descriptions of the program and the resultant information about contaminant pathways have been reported in Gartner and others (1998). This report primarily focused on the bottom boundary layer and the potential for resuspension and transport of sediments on the seabed in Sinclair Inlet as a result of tides and waves. Recently (2013), interest in transport pathways for suspended and dissolved materials in Sinclair Inlet has been rekindled. In particular, the USGS scientists in Washington and California have been asked to reexamine the datasets collected in the earlier study to refine not only our understanding of transport pathways through the inlet, but to determine how those transport pathways are affected by subtidal currents, local wind stress, and fresh water inputs. Because the prior study focused on the bottom boundary layer and not the water column, a reanalysis of the datasets could increase our understanding of the dynamic forces that drive transport within and through the inlet. However, the early datasets are limited in scope and a comprehensive understanding of these transport processes may require more extensive datasets or the development of a detailed numerical model of transport processes for the inlet, or both.

  12. Estuarine turbidity, flushing, salinity, and circulation

    NASA Technical Reports Server (NTRS)

    Pritchard, D. W.

    1972-01-01

    The effects of estuarine turbidity, flushing, salinity, and circulation on the ecology of the Chesapeake Bay are discussed. The sources of fresh water, the variations in salinity, and the circulation patterns created by temperature and salinity changes are analyzed. The application of remote sensors for long term observation of water temperatures is described. The sources of sediment and the biological effects resulting from increased sediments and siltation are identified.

  13. Circulating glioma biomarkers

    PubMed Central

    Kros, Johan M.; Mustafa, Dana M.; Dekker, Lennard J.M.; Sillevis Smitt, Peter A.E.; Luider, Theo M.; Zheng, Ping-Pin

    2015-01-01

    Validated biomarkers for patients suffering from gliomas are urgently needed for standardizing measurements of the effects of treatment in daily clinical practice and trials. Circulating body fluids offer easily accessible sources for such markers. This review highlights various categories of tumor-associated circulating biomarkers identified in blood and cerebrospinal fluid of glioma patients, including circulating tumor cells, exosomes, nucleic acids, proteins, and oncometabolites. The validation and potential clinical utility of these biomarkers is briefly discussed. Although many candidate circulating protein biomarkers were reported, none of these have reached the required validation to be introduced for clinical practice. Recent developments in tracing circulating tumor cells and their derivatives as exosomes and circulating nuclear acids may become more successful in providing useful biomarkers. It is to be expected that current technical developments will contribute to the finding and validation of circulating biomarkers. PMID:25253418

  14. The patterns and implications of diurnal variations in the d-excess of plant water, shallow soil water and air moisture

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Wang, L.; Liu, X.; Xiao, H.; Ruan, Y.; Zhou, M.

    2014-10-01

    Deuterium excess (d-excess) of air moisture is traditionally considered a conservative tracer of oceanic evaporation conditions. Recent studies challenge this view and emphasize the importance of vegetation activity in controlling the dynamics of air moisture d-excess. However, direct field observations supporting the role of vegetation in d-excess variations are not well documented. In this study, we quantified the d-excess of air moisture, shallow soil water (5 and 10 cm) and plant water (leaf, root and xylem) of multiple dominant species at hourly intervals during three extensive field campaigns at two climatically different locations within the Heihe River basin, northwestern China. The ecosystems at the two locations range from forest to desert. The results showed that with the increase in temperature (T) and the decrease in relative humidity (RH), the δD-δ18O regression lines of leaf water, xylem water and shallow soil water deviated gradually from their corresponding local meteoric water line. There were significant differences in d-excess values between different water pools at all the study sites. The most positive d-excess values were found in air moisture (9.3‰) and the most negative d-excess values were found in leaf water (-85.6‰). The d-excess values of air moisture (dmoisture) and leaf water (dleaf) during the sunny days, and shallow soil water (dsoil) during the first sunny day after a rain event, showed strong diurnal patterns. There were significantly positive relationships between dleaf and RH and negative relationships between dmoisture and RH. The correlations of dleaf and dmoisture with T were opposite to their relationships with RH. In addition, we found opposite diurnal variations for dleaf and dmoisture during the sunny days, and for dsoil and dmoisture during the first sunny day after the rain event. The steady-state Craig-Gordon model captured the diurnal variations in dleaf, with small discrepancies in the magnitude. Overall, this

  15. Sensitivity of the sea circulation to the atmospheric forcing in the Sicily Channel

    NASA Astrophysics Data System (ADS)

    Omrani, Hiba; Arsouze, Thomas; Béranger, Karine; Boukthir, Moncef; Drobinski, Philippe; Lebeaupin-Brossier, Cindy; Mairech, Hanen

    2016-01-01

    We investigate the sensitivity of the sea surface circulation in the Sicily Channel to surface winds, using a 15-year long (1994-2008) air-sea coupled numerical simulation. Analysis is based on the clustering of six main wind regimes over the Sicily Channel domain. The analysis of the corresponding sea current clusters shows that sea circulation in this area is sensitive to surface wind patterns. This wind modulates the strength of the two main branches of the sea circulation in the Sicily Channel (i.e. the Atlantic Tunisian Current and the Atlantic Ionian Stream). The modulation of these two currents depends on the wind regime, and displays a strong seasonal variability. It is also shown that the sea circulation in the Sicily Channel is strongly controlled by the thermohaline circulation and the bathymetry (geostrophic current). However, the contribution to the total current of its ageostrophic component forced by the surface winds is significant, with a correlation coefficient varying from 0.3 to 0.7.

  16. Comparative metabolomics analysis on invigorating blood circulation for herb pair Gui-Hong by ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry and pattern recognition approach.

    PubMed

    Li, Shujiao; Lin, Hang; Tang, Yuping; Li, Weixia; Shen, Juan; Kai, Jun; Yue, Shijun; Shang, Guanxiong; Zhu, Zhenhua; Shang, Erxin; Zhang, Changbin; Zhang, Li; Yan, Hui; Liu, Pei; Duan, Jin-ao

    2015-03-25

    The compatibility of Angelicae Sinensis Radix (Danggui, DG) and Flos Carthami (Honghua, HH), a famous herb pair Gui-Hong (GH), can produce synergistic and promoting blood effects. Although some physiological and pathological function parameters of the acute blood stasis have been investigated, little information about the changes of small metabolites in biofluids has been reported. In present study, global metabolic profiling with ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) combined with pattern recognition method was performed to discover the underlying blood-activating regulation mechanisms of DG, HH and GH on the acute blood stasis rats induced by subcutaneous injection of adrenaline hydrochloride and ice water bath. The total 14 metabolites (10 in urine and 4 in plasma), up regulated or down regulated (P<0.05 or 0.01), were identified and contributed to the acute blood stasis progress. These promising identified biomarkers underpin the metabolic pathway including phenylalanine metabolism, sphingolipid metabolism, arachidonic acid metabolism and arginine and proline metabolism are disturbed in the acute blood stasis rats, which identified by using pathway analysis with MetPA. The altered metabolites and hemorheological indexes could be regulated closer to normal level after DG, HH and GH intervention. In term of activate blood circulation function, GH was the most effective as shown by the relative distance in PLS-DA score plots and relative intensity of metabolomics trategy, reflecting the synergic action between Danggui and Honghua. The results demonstrated that biofluids metabolomics was a powerful tool in clinical diagnosis and treatment of syndrome of blood stasis for providing information on changes in metabolites pathways. PMID:25668798

  17. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    SciTech Connect

    Ibrahim, Essam A

    2013-01-09

    Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.

  18. Atmospheric Circulation Variability in the Tropics and the Northern Hemisphere During the Past 100 Years

    NASA Astrophysics Data System (ADS)

    Brönnimann, S.; Fischer, A. M.; Griesser, T.; Stickler, A.

    2009-04-01

    Documenting the variability of the large-scale atmospheric circulation during the past is important in order to better understand - and eventually predict - interannual-to-decadal climate variability. The large-scale tropical circulation features such as the Hadley and Walker cells and the monsoon systems play a particularly important role not only because of the effects within the tropics, but also because of their teleconnections to the extratropics. Here we present time series of large-scale atmospheric circulation indices back to 1900 and compare these with output from a 9-member "all forcings" ensemble calculation by a general circulation model. The indices represent the main features of the zonal mean circulation in the northern hemisphere in boreal winter (such as the Hadley circulation and the subtropical jet) as well as aspects of the regional and large-scale circulation (the Indian monsoon and the Pacific North American pattern, PNA). Back to 1948 the indices are taken from NCEP/NCAR reanalysis and are statistically reconstructed based on historical upper-air and surface data prior to 1948. We discuss the interannual-to-decadal variability of the index time series and compare them with possible driving factors, such as El Niño/Southern Oscillation, volcanic eruptions and solar activity. The results show that the interannual variability of the Hadley cell and subtropical jet is well reproduced in the model ensemble mean (and hence potentially predictable), whereas the poleward extent of the Hadley cell and the latitude of the subtropical jet are less well predictable. For all indices, the correlation between observations and model ensemble mean agree favourably well with the correlations between individual ensemble members. We find that the source of predictability is mainly related to ENSO. On the decadal scale small but significant effects of solar variability are found.

  19. Implementation of Tritium in the Lmdz-Iso General Circulation Model: First Promising Results for the Study of the Relationships Between Stratospheric Air Inputs into the Lower Troposphere in Polar Regions, Water Cycle and Climate

    NASA Astrophysics Data System (ADS)

    Cauquoin, A.; Jean Baptiste, P.; Risi, C. M.; Fourre, E.; Landais, A.

    2014-12-01

    Understanding the links between climate and water cycle is essential in the current context of global warming. The water isotopic composition, quantified as δD, δ18O or δ17O, has a great potential to trace the organization of present-day hydrological cycle. When recorded in various archives as tree rings, sediments, ice cores, they have also been largely used to reconstruct the past evolution of climate and water. The Antarctic cap is extremely sensitive to climate change. Moreover, this region is under the influence of exchanges between the troposphere and the stratosphere because of the presence of the polar vortex. Tritium (3H) has been shown to be an appropriate tracer for the intrusion of stratospheric air masses into the lower troposphere. Natural tritium is mainly produced by the interaction of cosmic radiations with the upper atmosphere. This tritium enters the hydrological cycle in the form of tritiated water molecules (HTO) and has a radioactive half-life of 4500±8 days. In an approach combining data and model, we have first implemented tritium in the coupled Laboratoire de Météorologie Dynamique Zoom (LMDZ) Atmospheric General Circulation Model developed at IPSL [Risi et al., 2010]: LMDZ-iso. The implementation of natural tritium uses the same model architecture as for the other water isotopes, after a correct description of associated cosmogenic production terms [Masarik and Beer, 2009]. The model is used in a configuration dedicated to the simulation of the stratosphere, with 39 layers. In this presentation, we will focus on the modeling of spatial and temporal natural variations of tritium content in precipitation. The model is validated against a compilation of available data for natural tritium. We show that the continental and latitudinal effects are well reproduced by the model and that simulated seasonal variations of the tritium content of precipitation are coherent with our current knowledge of troposphere-stratosphere exchanges. Masarik

  20. Apparatus Circulates Sterilizing Gas

    NASA Technical Reports Server (NTRS)

    Cross, John H.; Schwarz, Ray P.

    1991-01-01

    Apparatus circulates sterilizing gas containing ethylene oxide and chlorofluorocarbon through laboratory or medical equipment. Confines sterilizing gas, circulating it only through parts to be treated. Consists of two units. One delivers ethylene oxide/chlorofluorocarbon gas mixture and removes gas after treatment. Other warms, humidifies, and circulates gas through equipment to be treated. Process provides reliable sterilization with negligible residual toxicity from ethylene oxide. Particularly suitable for sterilization of interiors of bioreactors, heart/lung machines, dialyzers, or other equipment including complicated tubing.

  1. H3K9 acetylation change patterns in rats after exposure to traffic-related air pollution.

    PubMed

    Ding, Rui; Jin, Yongtang; Liu, Xinneng; Zhu, Ziyi; Zhang, Yuan; Wang, Ting; Xu, Yinchun

    2016-03-01

    Traffic-related air pollution (TRAP) has been acknowledged as a potential risk factor for numerous respiratory disorders including lung cancer; however, the exact mechanisms involved are still unclear. Here we investigated the effects of TRAP exposure on the H3K9 acetylation in rats. The exposure was performed in both spring and autumn with identical study procedures. In each season, 48 healthy Wistar rats were exposed to different levels of TRAP for 4 h, 7 d, 14 d, and 28 d, respectively. H3K9 acetylation levels in both the peripheral blood mononuclear cells (PBMCs) and lung tissues were quantified. Multiple linear regression was applied to assess the influence of air pollutants on H3K9 acetylation levels. The levels of PM2.5, PM10, and NO2 in the tunnel and crossroad groups were significantly higher than in the control group. The H3K9 acetylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, no significant association between the TRAP and H3K9 acetylation was found in 4h exposure window. However, in the 7 d exposure window, PM2.5 and PM10 exposures were associated with changes in H3K9 acetylation ranging from 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) per 1 μg/m(3) increase in the pollutant concentration. In addition, prolonged exposure of the rats in the tunnel showed that both PM2.5 and PM10 concentrations were positively associated with H3k9 acetylation in both PBMCs and lung tissues. The findings showed that 7-d and prolonged TRAP exposure could effectively increase the H3K9 acetylation level in both PBMCs and lung tissues of rats.

  2. Experimental and numerical investigation on air-side performance of fin-and-tube heat exchangers with various fin patterns

    SciTech Connect

    Tang, L.H.; Zeng, M.; Wang, Q.W.

    2009-07-15

    Air-side heat transfer and friction characteristics of five kinds of fin-and-tube heat exchangers, with the number of tube rows (N = 12) and the diameter of tubes (D{sub o} = 18 mm), have been experimentally investigated. The test samples consist of five types of fin configurations: crimped spiral fin, plain fin, slit fin, fin with delta-wing longitudinal vortex generators (VGs) and mixed fin with front 6-row vortex-generator fin and rear 6-row slit fin. The heat transfer and friction factor correlations for different types of heat exchangers were obtained with the Reynolds numbers ranging from 4000 to 10000. It was found that crimped spiral fin provides higher heat transfer and pressure drop than the other four fins. The air-side performance of heat exchangers with the above five fins has been evaluated under three sets of criteria and it was shown that the heat exchanger with mixed fin (front vortex-generator fin and rear slit fin) has better performance than that with fin with delta-wing vortex generators, and the slit fin offers best heat transfer performance at high Reynolds numbers. Based on the correlations of numerical data, Genetic Algorithm optimization was carried out, and the optimization results indicated that the increase of VG attack angle or length, or decrease of VG height may enhance the performance of vortex-generator fin. The heat transfer performances for optimized vortex-generator fin and slit fin at hand have been compared with numerical method. (author)

  3. Using non-negative matrix factorization for the identification of daily patterns of particulate air pollution in Beijing during 2004-2008

    NASA Astrophysics Data System (ADS)

    Thiem, A.; Schlink, U.; Pan, X.-C.; Hu, M.; Peters, A.; Wiedensohler, A.; Breitner, S.; Cyrys, J.; Wehner, B.; Rösch, C.; Franck, U.

    2012-05-01

    Increasing traffic density and a changing car fleet on the one hand as well as various reduction measures on the other hand may influence the composition of the particle population and, hence, the health risks for residents of megacities like Beijing. A suitable tool for identification and quantification of source group-related particle exposure compositions is desirable in order to derive optimal adaptation and reduction strategies and therefore, is presented in this paper. Particle number concentrations have been measured in high time- and space-resolution at an urban background monitoring site in Beijing, China, during 2004-2008. In this study a new pattern recognition procedure based on non-negative matrix factorization (NMF) was introduced to extract characteristic diurnal air pollution patterns of particle number and volume size distributions for the study period. Initialization and weighting strategies for NMF applications were carefully considered and a scaling procedure for ranking of obtained patterns was implemented. In order to account for varying particle sizes in the full diameter range [3 nm; 10 μm] two separate NMF applications (a) for diurnal particle number concentration data (NMF-N) and (b) volume concentration data (NMF-V) have been performed. Five particle number concentration-related NMF-N factors were assigned to patterns mainly describing the development of ultrafine (particle diameter Dp < 100 nm instead of DP) as well as fine particles (Dp < 2.5 μm), since absolute number concentrations are highest in these diameter ranges. The factors are classified into primary and secondary sources. Primary sources mostly involved anthropogenic emission sources such as traffic emissions or emissions of nearby industrial plants, whereas secondary sources involved new particle formation and accumulation (particle growth) processes. For the NMF-V application the five extracted factors mainly described coarse particle (2.5 μm < Dp < 10 μm) variations

  4. Ocean circulation and climate change

    NASA Astrophysics Data System (ADS)

    Hasselmann, Klaus

    1991-09-01

    Recent numerical simulations using global ocean circulation models are reviewed together with model experiments involving further important climate sub-systems with which the ocean interacts: the atmosphere, the air-sea interface and the global carbon cycle. A common feature of all ocean circulation experiments considered is the strong sensitivity of the circulation to relatively minor changes in surface forcing, particularly to the buoyancy fluxes in regions of deep water formation in high latitudes. This may explain some of the well-known deficiencies of past global ocean circulation simulations. The strong sensitivity may also have been the cause of rapid climate changes observed in paleoclimatic records and can lead further to significant natural climate variability on the time scales of a few hundred years through the stochastic forcing of the ocean by atmospheric weather variability. Gobal warming computations using two different coupled ocean-atmosphere models for the "business-as-usual" scenario of the Intergovernmental Panel on Climate Change yield a significantly stronger warming delay due to the heat uptake by the oceans in the Southern Ocean than estimated on the basis of box-diffusion models. Recent advances in surface wave modelling, illustrated by a comparison of wave height fields derived from the WAM model and the GEOSAT altimeter, hold promise for the development of an improved representation of ocean-atmosphere coupling based on an explicit description of the dynamical processes at the air-sea interface. Global carbon cycle simulations with a three dimensional carbon cycle model tuned to reproduce past variations of carbon cycle indices show a significant impact of variations in the ocean circulation on the CO2 concentration in the atmosphere and thereby on climate. The series of experiments suggest that for the study of climate in the time scale range from 10-Ocean circulation and climate change

    NASA Astrophysics Data System (ADS)

    Hasselmann, Klaus

    1991-08-01

    Recent numerical simulations using global ocean circulation models are reviewed together with model experiments involving further important climate sub-systems with which the ocean interacts: the atmosphere, the air-sea interface and the global carbon cycle. A common feature of all ocean circulation experiments considered is the strong sensitivity of the circulation to relatively minor changes in surface forcing, particularly to the buoyancy fluxes in regions of deep water formation in high latitudes. This may explain some of the well-known deficiencies of past global ocean circulation simulations. The strong sensitivity may also have been the cause of rapid climate changes observed in paleoclimatic records and can lead further to significant natural climate variability on the time scales of a few hundred years through the stochastic forcing of the ocean by atmospheric weather variability. Gobal warming computations using two different coupled ocean-atmosphere models for the "business-as-usual" scenario of the Intergovernmental Panel on Climate Change yield a significantly stronger warming delay due to the heat uptake by the oceans in the Southern Ocean than estimated on the basis of box-diffusion models. Recent advances in surface wave modelling, illustrated by a comparison of wave height fields derived from the WAM model and the GEOSAT altimeter, hold promise for the development of an improved representation of ocean-atmosphere coupling based on an explicit description of the dynamical processes at the air-sea interface. Global carbon cycle simulations with a three dimensional carbon cycle model tuned to reproduce past variations of carbon cycle indices show a significant impact of variations in the ocean circulation on the CO2 concentration in the atmosphere and thereby on climate. The series of experiments suggest that for the study of climate in the time scale range from 10-Circulation of HRSV in Belgium: from multiple genotype circulation to prolonged circulation of predominant genotypes.

    PubMed

    Houspie, Lieselot; Lemey, Philippe; Keyaerts, Els; Reijmen, Eva; Vergote, Valentijn; Vankeerberghen, Anne; Vaeyens, Freya; De Beenhouwer, Hans; Van Ranst, Marc

    2013-01-01

    Molecular surveillance of HRSV in Belgium for 15 consecutive seasons (1996-2011) revealed a shift from a regular 3-yearly cyclic pattern, into a yearly alternating periodicity where HRSV-B is replaced by HRSV-A. Phylogenetic analysis for HRSV-A demonstrated the stable circulation of GA2 and GA5, with GA2 being dominant over GA5 during 5 consecutive seasons (2006-2011). We also identified 2 new genotype specific amino acid mutations of the GA2 genotype (A122 and Q156) and 7 new GA5 genotype specific amino acid mutations (F102, I108, T111, I125, D161, S191 and L217). Several amino acid positions, all located in the second hypervariable region of HRSV-A were found to be under positive selection. Phylogenetic analysis of HRSV-B showed the circulation of GB12 and GB13, where GB13 represented 100% of the isolated strains in 4 out of 5 consecutive seasons (2007-2011). Amino acids under positive selection were all located in the aminoterminal hypervariable region of HRSV-B, except one amino acid located in the conserved region. The genotype distribution within the HRSV-B subgroup has evolved from a co-circulation of multiple genotypes to the circulation of a single predominant genotype. The Belgian GB13 strains circulating since 2006, all clustered under the BAIV branch and contained several branch specific amino acid substitutions. The demographic history of genotypes GA2, GA5 and GB13 demonstrated a decrease in the total GA2 and GA5 population size, coinciding with the global expansion of the GB13 population. The emergence of the GB13 genotype resulted in a newly established balance between the predominant genotypes. PMID:23577109

  5. City-Specific Spatiotemporal Infant and Neonatal Mortality Clusters: Links with Socioeconomic and Air Pollution Spatial Patterns in France.

    PubMed

    Padilla, Cindy M; Kihal-Talantikit, Wahida; Vieira, Verónica M; Deguen, Séverine

    2016-01-01

    Infant and neonatal mortality indicators are known to vary geographically, possibly as a result of socioeconomic and environmental inequalities. To better understand how these factors contribute to spatial and temporal patterns, we conducted a French ecological study comparing two time periods between 2002 and 2009 for three (purposefully distinct) Metropolitan Areas (MAs) and the city of Paris, using the French census block of parental residence as the geographic unit of analysis. We identified areas of excess risk and assessed the role of neighborhood deprivation and average nitrogen dioxide concentrations using generalized additive models to generate maps smoothed on longitude and latitude. Comparison of the two time periods indicated that statistically significant areas of elevated infant and neonatal mortality shifted northwards for the city of Paris, are present only in the earlier time period for Lille MA, only in the later time period for Lyon MA, and decrease over time for Marseille MA. These city-specific geographic patterns in neonatal and infant mortality are largely explained by socioeconomic and environmental inequalities. Spatial analysis can be a useful tool for understanding how risk factors contribute to disparities in health outcomes ranging from infant mortality to infectious disease-a leading cause of infant mortality. PMID:27338439

  6. City-Specific Spatiotemporal Infant and Neonatal Mortality Clusters: Links with Socioeconomic and Air Pollution Spatial Patterns in France

    PubMed Central

    Padilla, Cindy M.; Kihal-Talantikit, Wahida; Vieira, Verónica M.; Deguen, Séverine

    2016-01-01

    Infant and neonatal mortality indicators are known to vary geographically, possibly as a result of socioeconomic and environmental inequalities. To better understand how these factors contribute to spatial and temporal patterns, we conducted a French ecological study comparing two time periods between 2002 and 2009 for three (purposefully distinct) Metropolitan Areas (MAs) and the city of Paris, using the French census block of parental residence as the geographic unit of analysis. We identified areas of excess risk and assessed the role of neighborhood deprivation and average nitrogen dioxide concentrations using generalized additive models to generate maps smoothed on longitude and latitude. Comparison of the two time periods indicated that statistically significant areas of elevated infant and neonatal mortality shifted northwards for the city of Paris, are present only in the earlier time period for Lille MA, only in the later time period for Lyon MA, and decrease over time for Marseille MA. These city-specific geographic patterns in neonatal and infant mortality are largely explained by socioeconomic and environmental inequalities. Spatial analysis can be a useful tool for understanding how risk factors contribute to disparities in health outcomes ranging from infant mortality to infectious disease—a leading cause of infant mortality. PMID:27338439

  7. City-Specific Spatiotemporal Infant and Neonatal Mortality Clusters: Links with Socioeconomic and Air Pollution Spatial Patterns in France.

    PubMed

    Padilla, Cindy M; Kihal-Talantikit, Wahida; Vieira, Verónica M; Deguen, Séverine

    2016-01-01

    Infant and neonatal mortality indicators are known to vary geographically, possibly as a result of socioeconomic and environmental inequalities. To better understand how these factors contribute to spatial and temporal patterns, we conducted a French ecological study comparing two time periods between 2002 and 2009 for three (purposefully distinct) Metropolitan Areas (MAs) and the city of Paris, using the French census block of parental residence as the geographic unit of analysis. We identified areas of excess risk and assessed the role of neighborhood deprivation and average nitrogen dioxide concentrations using generalized additive models to generate maps smoothed on longitude and latitude. Comparison of the two time periods indicated that statistically significant areas of elevated infant and neonatal mortality shifted northwards for the city of Paris, are present only in the earlier time period for Lille MA, only in the later time period for Lyon MA, and decrease over time for Marseille MA. These city-specific geographic patterns in neonatal and infant mortality are largely explained by socioeconomic and environmental inequalities. Spatial analysis can be a useful tool for understanding how risk factors contribute to disparities in health outcomes ranging from infant mortality to infectious disease-a leading cause of infant mortality.

  8. Circulation control STOL aircraft design aspects

    NASA Technical Reports Server (NTRS)

    Loth, John L.

    1987-01-01

    Since Davidson patented Circulation Control Airfoils in 1960, there have been only 2 aircraft designed and flown with circulation control (CC). Designing with CC is complex for the following reasons: the relation between lift increase and blowing momentum is nonlinear; for good cruise performance one must change the wing geometry in flight from a round to a sharp trailing edge. The bleed air from the propulsion engines or an auxiliary compressor, must be used efficiently. In designing with CC, the propulsion and control aspects are just as important as aerodynamics. These design aspects were examined and linearized equations are presented in order to facilitate a preliminary analysis of the performance potential of CC. The thrust and lift requirements for takeoff make the calculated runway length very sensitive to the bleed air ratio. Thrust vectoring improves performance and can offset nose down pitching moments. The choice of blowing jet to free stream velocity ratio determines the efficiency of applying bleed air power.

  9. Air-permeable hole-pattern and nose-droop control improve aerodynamic performance of primary feathers.

    PubMed

    Eder, Heinrich; Fiedler, Wolfgang; Pascoe, Xaver

    2011-01-01

    Primary feathers of soaring land birds have evolved into highly specialized flight feathers characterized by morphological improvements affecting aerodynamic performance. The foremost feathers in the cascade have to bear high lift-loading with a strong bending during soaring flight. A challenge to the study of feather aerodynamics is to understand how the observed low drag and high lift values in the Reynolds (Re) regime from 1.0 to 2.0E4 can be achieved. Computed micro-tomography images show that the feather responds to high lift-loading with an increasing nose-droop and profile-camber. Wind-tunnel tests conducted with the foremost primary feather of a White Stork (Ciconia ciconia) at Re = 1.8E4 indicated a surprisingly high maximum lift coefficient of 1.5 and a glide ratio of nearly 10. We present evidence that this is due to morphologic characteristics formed by the cristae dorsales as well as air-permeable arrays along the rhachis. Measurements of lift and drag forces with open and closed pores confirmed the efficiency of this mechanism. Porous structures facilitate a blow out, comparable to technical blow-hole turbulators for sailplanes and low speed turbine-blades. From our findings, we conclude that the mechanism has evolved in order to affect the boundary layer and to reduce aerodynamic drag of the feather.

  10. Regional patterns of radiocarbon and fossil fuel-derived CO2 in surface air across North America

    NASA Astrophysics Data System (ADS)

    Hsueh, Diana Y.; Krakauer, Nir Y.; Randerson, James T.; Xu, Xiaomei; Trumbore, Susan E.; Southon, John R.

    2007-01-01

    Radiocarbon levels in annual plants provide a means to map out regional and continental-scale fossil fuel plumes in surface air. We collected corn (Zea mays) across North America during the summer of 2004. Plants from mountain regions of western North America showed the smallest influence of fossil fuel-derived CO2 with a mean Δ14C of 66.3‰ +/-1.7‰. Plants from eastern North America and from the Ohio-Maryland region showed a larger fossil fuel influence with a mean Δ14C of 58.8‰ +/- 3.9‰ and 55.2‰ +/- 2.3‰, respectively, corresponding to 2.7 ppm +/- 1.5 ppm and 4.3 ppm +/- 1.0 ppm of added fossil fuel CO2 relative to the mountain west. A model-data comparison suggests that surveys of annual plant Δ14C can provide a useful test of atmospheric mixing in transport models that are used to estimate the spatial distribution of carbon sources and sinks.

  11. Air-permeable hole-pattern and nose-droop control improve aerodynamic performance of primary feathers.

    PubMed

    Eder, Heinrich; Fiedler, Wolfgang; Pascoe, Xaver

    2011-01-01

    Primary feathers of soaring land birds have evolved into highly specialized flight feathers characterized by morphological improvements affecting aerodynamic performance. The foremost feathers in the cascade have to bear high lift-loading with a strong bending during soaring flight. A challenge to the study of feather aerodynamics is to understand how the observed low drag and high lift values in the Reynolds (Re) regime from 1.0 to 2.0E4 can be achieved. Computed micro-tomography images show that the feather responds to high lift-loading with an increasing nose-droop and profile-camber. Wind-tunnel tests conducted with the foremost primary feather of a White Stork (Ciconia ciconia) at Re = 1.8E4 indicated a surprisingly high maximum lift coefficient of 1.5 and a glide ratio of nearly 10. We present evidence that this is due to morphologic characteristics formed by the cristae dorsales as well as air-permeable arrays along the rhachis. Measurements of lift and drag forces with open and closed pores confirmed the efficiency of this mechanism. Porous structures facilitate a blow out, comparable to technical blow-hole turbulators for sailplanes and low speed turbine-blades. From our findings, we conclude that the mechanism has evolved in order to affect the boundary layer and to reduce aerodynamic drag of the feather. PMID:20938776

  12. Extreme Temperature Regimes during the Cool Season and their Associated Large-Scale Circulations

    NASA Astrophysics Data System (ADS)

    Xie, Z.

    2015-12-01

    In the cool season (November-March), extreme temperature events (ETEs) always hit the continental United States (US) and provide significant societal impacts. According to the anomalous amplitudes of the surface air temperature (SAT), there are two typical types of ETEs, e.g. cold waves (CWs) and warm waves (WWs). This study used cluster analysis to categorize both CWs and WWs into four distinct regimes respectively and investigated their associated large-scale circulations on intra-seasonal time scale. Most of the CW regimes have large areal impact over the continental US. However, the distribution of cold SAT anomalies varies apparently in four regimes. In the sea level, the four CW regimes are characterized by anomalous high pressure over North America (near and to west of cold anomaly) with different extension and orientation. As a result, anomalous northerlies along east flank of anomalous high pressure convey cold air into the continental US. To the middle troposphere, the leading two groups feature large-scale and zonally-elongated circulation anomaly pattern, while the other two regimes exhibit synoptic wavetrain pattern with meridionally elongated features. As for the WW regimes, there are some patterns symmetry and anti-symmetry with respect to CW regimes. The WW regimes are characterized by anomalous low pressure and southerlies wind over North America. The first and fourth groups are affected by remote forcing emanating from North Pacific, while the others appear mainly locally forced.

  13. Isentropic analysis of the Indian Summer Monsoon circulation and its implications for the active and break periods

    NASA Astrophysics Data System (ADS)

    Pauluis, O. M.; Sandeep, S.; Ravindran, A. M.

    2014-12-01

    The atmospheric flow during the Indian Summer Monsoon here is analyzed in isentropic coordinates in two different ways. First, the lateral mass transport fo air is separated in terms of both the potential temperature and equivalent potential temperature. This approach, originally developed to analyze the global meridional circulation, makes it possible to identify the thermodynamic properties of the inflow and outflow. It is shown here how the properties of various air masses, such as the inflow of warm moist air in the boundary layer, upper tropospheric outflow, and midlatitudes dry air intrusion, can be systematically identified. Second, we analyze the vertical overturning in terms of terms of the equivalent potential temperature of the ascending and subsiding air parcels over the indian subcontinent, which allows us to further infer the thermodynamic transformation occurring during the monsoon. This technique is first used to look at the evolution of the flow through the seasonal cycle. We then further analyze the circulation patterns associated with monsoon breaks and active periods. In doing so, we identify midtropospheric in usions of dry air from the midlatitudes as a key precursor of monsoon breaks. The meteorological conditions associated for such intrusion to reach the subcontinent are then discussed.

  14. Recurring Cold Winters over the Gulf Stream and Implications for Northern Hemisphere Ocean Circulation

    NASA Astrophysics Data System (ADS)

    Strey, S. T.

    2015-12-01

    As polar amplification of climate warming continues, the potential for increased blocking patterns in the Northern Hemisphere jet stream in conjunction with Arctic climate change exists. During such blocking events the Gulf Stream may be exposed to repeated Cold Air Outbreak (CAO) events, especially during winter. Hypothesizing, based upon basic physical and thermodynamic properties of seawater, one would expect increased CAO events to lead alteration of key characteristics of the Gulf Stream. As the Gulf Stream is a well-known participant in the Atlantic meridional overturning circulation (AMOC), and the Gulf Stream feeds the North Atlantic Current into the Arctic Ocean, interesting consequences to alterations of this local system into the large-scale general climate circulation are expected. This study uses CESM's POP to examine 30 years of CAO intensive winters alongside 30 years of repeated winter warm events to quantify potential subsequent changes in the AMOC and North Atlantic Arctic Ocean inflow.

  15. X-ray Lithography on Perovskite Nanocrystals Films: From Patterning with Anion-Exchange Reactions to Enhanced Stability in Air and Water

    PubMed Central

    2015-01-01

    Films of colloidal CsPbX3 (X = I, Br or Cl) nanocrystals, prepared by solution drop-casting or spin-coating on a silicon substrate, were exposed to a low flux of X-rays from an X-ray photoelectron spectrometer source, causing intermolecular C=C bonding of the organic ligands that coat the surface of the nanocrystals. This transformation of the ligand shell resulted in a greater stability of the film, which translated into the following features: (i) Insolubility of the exposed regions in organic solvents which caused instead complete dissolution of the unexposed regions. This enabled the fabrication of stable and strongly fluorescent patterns over millimeter scale areas. (ii) Inhibition of the irradiated regions toward halide anion exchange reactions, when the films were exposed either to halide anions in solution or to hydrohalic vapors. This feature was exploited to create patterned regions of different CsPbIxBryClz compositions, starting from a film with homogeneous CsPbX3 composition. (iii) Resistance of the films to degradation caused by exposure to air and moisture, which represents one of the major drawbacks for the integration of these materials in devices. (iv) Stability of the film in water and biological buffer, which can open interesting perspectives for applications of halide perovskite nanocrystals in aqueous environments. PMID:26617344

  16. Biogeography in the air: fungal diversity over land and oceans

    NASA Astrophysics Data System (ADS)

    Fröhlich-Nowoisky, J.; Burrows, S. M.; Xie, Z.; Engling, G.; Solomon, P. A.; Fraser, M. P.; Mayol-Bracero, O. L.; Artaxo, P.; Begerow, D.; Conrad, R.; Andreae, M. O.; Després, V. R.; Pöschl, U.

    2011-07-01

    Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we found that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental air than in marine air. This may be an important difference between the "blue ocean" and "green ocean" regimes in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that air flow patterns and the global atmospheric circulation are important for the evolution of microbial ecology and for the understanding of global changes in biodiversity.

  17. Biogeography in the air: fungal diversity over land and oceans

    NASA Astrophysics Data System (ADS)

    Fröhlich-Nowoisky, J.; Burrows, S. M.; Xie, Z.; Engling, G.; Solomon, P. A.; Fraser, M. P.; Mayol-Bracero, O. L.; Artaxo, P.; Begerow, D.; Conrad, R.; Andreae, M. O.; Després, V. R.; Pöschl, U.

    2012-03-01

    Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we find that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental air than in marine air. This may be an important difference between the "blue ocean" and "green ocean" regimes in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that air flow patterns and the global atmospheric circulation are important for the understanding of global changes in biodiversity.

  18. Cross-correlation patterns of air and soil temperatures, rainfall and Diaprepes abbreviatus root weevil in citrus.

    PubMed

    Li, Hong; Futch, Stephen H; Syvertsen, James P

    2007-11-01

    Time series cross-correlation analysis is appropriate when measuring relationships between two different time series. Using this approach, the authors quantified the relationship between the time series air temperature (AT), soil temperature (ST), rainfall, relative humidity (RH) and Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae) root weevil across a period of 30 months, and examined how closely the distribution of Diaprepes root weevil was related to AT, ST, rainfall and RH within this period of time. The study was conducted on a poorly drained Spodosol in a citrus [Citrus sinensis (L.) Osb.] grove in DeSoto County, south-west Florida, from April 2001 to September 2003. Adult weevil populations were monitored using 100 Tedders traps in a 30 x 15 m grid. Weather data (0.6 m AT, 0.1 m ST, 2 m rainfall and 2 m RH) were monitored by Florida Automated Weather Networks. The monthly mean and standard deviation were 22.3 +/- 4.0 degrees C for AT, 24.7 +/- 4.2 degrees C for ST, 146.0 +/- 122.7 mm for rainfall, 78.2 +/- 4.7% for RH and 0.74 +/- 0.59 adults trap(-1) for the root weevil. Weevil density was positively correlated with AT (r = 0.45, P < 0.0133), ST (r = 0.49, P < 0.0067) and rainfall (r = 0.38, P < 0.0450). The environmental variables AT, ST, rainfall and RH were correlated with each other (0.42 < r < 0.99, 0.0246 < P < 0.0001). All weather and Diaprepes variables were autocorrelated with each other within a time of 3 months. The cross-correlation coefficients varied between - 0.59 and 0.65 for the pair-variable between Diaprepes, AT, ST and rainfall, and these pair-variables were correlated across a time period of 4 months. The present results suggested that warm, wet conditions contributed to the root weevil outbreaks, and environmental temperature and rainfall were the variables most closely related to Diaprepes root weevil distribution in time. PMID:17674428

  1. Effects of winter atmospheric circulation on temporal and spatial variability in annual streamflow in the western United States

    USGS Publications Warehouse

    McCabe, G.J.

    1996-01-01

    Winter mean 700-hectoPascal (hPa) height anomalies, representing the average atmospheric circulation during the snow season, are compared with annual streamflow measured at 140 streamgauges in the western United States. Correlation and anomaly pattern analyses are used to identify relationships between winter mean atmospheric circulation and temporal and spatial variability in annual streamflow. Results indicate that variability in winter mean 700-Hpa height anomalies accounts for a statistically significant portion of the temporal variability in annual streamflow in the western United States. In general, above-average annual streamflow is associated with negative winter mean 700-Hpa height anomalies over the eastern North Pacific Ocean and/or the western United States. The anomalies produce an anomalous flow of moist air from the eastern North Pacific Ocean into the western United States that increases winter precipitation and snowpack accumulations, and subsequently streamflow. Winter mean 700-hPa height anomalies also account for statistically significant differences in spatial distributions of annual streamflow. As part of this study, winter mean atmospheric circulation patterns for the 40 years analysed were classified into five winter mean 700-hPa height anomaly patterns. These patterns are related to statistically significant and physically meaningful differences in spatial distributions of annual streamflow.

  2. Circulating serotonin in vertebrates.

    PubMed

    Maurer-Spurej, E

    2005-08-01

    The role of circulating serotonin is unclear and whether or not serotonin is present in the blood of non-mammalian species is not known. This study provides the first evidence for the presence of serotonin in thrombocytes of birds and three reptilian species, the endothermic leatherback sea turtle, the green sea turtle and the partially endothermic American alligator. Thrombocytes from a fresh water turtle, American bullfrog, Yellowfin tuna, and Chinook salmon did not contain serotonin. Serotonin is a vasoactive substance that regulates skin blood flow, a major mechanism for endothermic body temperature regulation, which could explain why circulating serotonin is present in warm-blooded species. The temperature sensitivity of human blood platelets with concomitant changes in serotonin content further supports a link between circulating serotonin and thermoregulation. Phylogenetic comparison of the presence of circulating serotonin indicated an evolutionary divergence within reptilian species that might coincide with the emergence of endothermy. PMID:16041566

  3. Structural Determination of Circulation.

    ERIC Educational Resources Information Center

    Blankenburg, William B.

    1981-01-01

    Analyzes the effects of both structural factors (demographics, economic conditions, and competition) and discretionary factors (content, design, and marketing techniques) and concludes that it is the former that determine a newspaper's circulation. (FL)

  4. Atmospheric Circulation and Dynamics

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay S.; Rengel, Miriam

    The deep atmosphere of Venus ( ˜ 180 km including the thermosphere) presents both observational and modeling challenges. Its thick, nearly uniform global cloud cover makes it difficult to fathom the vertical structure of the global circulation through available techniques that are applied to Earth's atmosphere. Further, the slow rotation of the planet and the consequential prevailing cyclostrophic balance restricts easy inferences about the meridional flow and circulation (Gierasch et al. 1997, Read 1986, Schubert et al. 2007).

  5. Circulating venous bubbles in children after diving.

    PubMed

    Lemaitre, Frederic; Carturan, Daniel; Tourney-Chollet, Claire; Gardette, Bernard

    2009-02-01

    Doppler ultrasonic detection of circulating venous bubbles after a scuba dive is a useful index of decompression safety in adults, since a relationship between bubbles and the risk of decompression sickness has been documented. No study, however, has investigated circulating venous bubbles in young recreational divers after their usual dives. The aim of this study was to determine whether these bubbles would be detected in children who performed a single dive without any modification in their diving habits. Ten young recreational divers (13.1 +/- 2.3 years) performed their usual air dive. They were Doppler-monitored 20 min before the dive (12 +/- 3 m for 26 +/- 7 min) and for 60 min after surfacing, at 20-min intervals. No circulating venous bubbles were detected after the children surfaced. The results showed that during a usual shallow diving session, venous bubbles were not detected in children.

  6. Link between North Atlantic wave climate and circulation changes

    SciTech Connect

    Cardone, V.J.; Greenwood, J.G.; Kushnir, Y.; Cane, M.A.

    1994-12-31

    A secular trend in the mean wave height of the North Atlantic (NA) Ocean has been proposed recently by Bacon and Carter (1991). This estimate was based mainly upon the analysis of wave observations from Seven Stones Light Vessel (SSLV) (1962--1986) located off the southwest tip of England, and Ocean Weather Station Lima (LIMA) (1975--1988) at 57{degree}N, 20{degree}W. The positive trend in the annual mean originates mainly in the monthly means for December, January and February. Kushnir (1994) reports a pattern of NA ocean-atmosphere interaction that indicates a change in the mean low level atmospheric circulation beginning around 1960. This change corresponds to a gradual increase in sea-level pressure in the central NA Ocean. Kushnir linked the change to interdecadal variations in NA sea surface temperature. This raises the possibility that the change in wave climate is associated with this interdecadal air-sea interaction. In this study, this possibility is explored by first hindcasting the sea state over the entire NA over a 10-year period using a calibrated hindcast method and then correlating the variations in the hindcast monthly and seasonal wave height means in the Northeast NA with variations in the circulation index used by Kushnir to monitor changes in the large-scale low level atmospheric circulation. The positive correlation found between these variations, especially during the winter, provides a plausible explanation for the proposed trend in wave climate off the Northwest Coast of Europe as a manifestation of a longer term interdecadal variation resembling the North Atlantic Oscillation.

  7. Assessing Patterns in the Surface Electric Field Prior to First CG Flashes and After Last CG Flashes in Air-Mass Thunderstorms

    NASA Astrophysics Data System (ADS)

    Williams, D. E.; Beasley, W. H.; Hyland, P. T.

    2007-12-01

    In an effort to elicit patterns in the temporal and spatial evolution of the contours of surface electric field relevant to the occurrence of cloud-to-ground (CG) lightning, we have analyzed data from the network of 31 electric-field mills jointly operated by the John F. Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). To identify cases of interest, we used lightning ground-strike data, maps of in-cloud lightning discharges, rainfall data, and radar data. In particular, we have focused on two critical problems: 1) estimation of when and where the first CG flash in a storm might occur and 2) assessment of the likelihood of CG flashes occurring late in a storm after a long period without a CG flash. Our long-term goal is to understand the evolution of surface contours of electric field for periods of 30 minutes or more before the first flash of any kind and 30 minutes or more before and after the last flash of any kind. For practical reasons, we are reporting here on analysis of data for periods of 30 minutes before the first CG flash and 30 minutes after the last CG flash in each storm of interest. We have analyzed electric-field data from isolated air-mass convective storms that developed over KSC/CCAFS from late May through early September, 2004-2006. To identify thunderstorms that fit the air-mass, or "pop-up" criteria, we started by examining rainfall and CG lightning data, then looked at radar data. Then, for the storms selected, we performed a two-pass Barnes objective analysis on the electric-field data. Each analysis cycle resulted in one contour plot of 20-second averaged data, yielding 90 plots for each 30 minute interval, which we then animated. This resulted in 58 animations of the field contours prior to first CG flashes and 62 animations of the field contours after last CG flashes. Preliminary impressions from examinations of these cases suggest that the electric-field contours before the first flash exhibit a smooth transition

  8. Rotor blade construction for circulation control aircraft

    NASA Technical Reports Server (NTRS)

    Carter, Sr., Donald R. (Inventor); Krauss, Timothy A. (Inventor); Sedlak, Matthew (Inventor)

    1986-01-01

    A circulation control aircraft rotor blade having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible composite material panels 18 cooperating with the surface to define slots for the discharge of compressed air from within the blade with each panel having first flexure means 60 associated with screw adjustments 36 for establishing a slot opening preload and second flexure means 62 associated with screw adjustments 38 for establishing a slot maximum opening.

  9. Relations between winter precipitation and atmospheric circulation simulated by the Geophysical Fluid Dynamics Laboratory general circulation model

    USGS Publications Warehouse

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

    1995-01-01

    General circulation model (GCM) simulations of atmospheric circulation are more reliable than GCM simulations of temperature and precipitation. In this study, temporal correlations between 700 hPa height anomalies simulated winter precipitation at eight locations in the conterminous United States are compared with corresponding correlations in observations. The objectives are to 1) characterize the relations between atmospheric circulation and winter precipitation simulated by the GFDL, GCM for selected locations in the conterminous USA, ii) determine whether these relations are similar to those found in observations of the actual climate system, and iii) determine if GFDL-simulated precipitation is forced by the same circulation patterns as in the real atmosphere. -from Authors

  10. Summertime land-sea thermal contrast and atmospheric circulation over East Asia in a warming climate—Part I: Past changes and future projections

    NASA Astrophysics Data System (ADS)

    Kamae, Youichi; Watanabe, Masahiro; Kimoto, Masahide; Shiogama, Hideo

    2014-11-01

    Land-sea surface air temperature (SAT) contrast, an index of tropospheric thermodynamic structure and dynamical circulation, has shown a significant increase in recent decades over East Asia during the boreal summer. In Part I of this two-part paper, observational data and the results of transient warming experiments conducted using coupled atmosphere-ocean general circulation models (GCMs) are analyzed to examine changes in land-sea thermal contrast and the associated atmospheric circulation over East Asia from the past to the future. The interannual variability of the land-sea SAT contrast over the Far East for 1950-2012 was found to be tightly coupled with a characteristic tripolar pattern of tropospheric circulation over East Asia, which manifests as anticyclonic anomalies over the Okhotsk Sea and around the Philippines, and a cyclonic anomaly over Japan during a positive phase, and vice versa. In response to CO2 increase, the cold northeasterly winds off the east coast of northern Japan and the East Asian rainband were strengthened with the circulation pattern well projected on the observed interannual variability. These results are commonly found in GCMs regardless of future forcing scenarios, indicating the robustness of the East Asian climate response to global warming. The physical mechanisms responsible for the increase of the land-sea contrast are examined in Part II.

  11. Response of air stagnation frequency to anthropogenically enhanced radiative forcing.

    PubMed

    Horton, Daniel E; Harshvardhan; Diffenbaugh, Noah S

    2012-01-01

    Stagnant atmospheric conditions can lead to hazardous air quality by allowing ozone and particulate matter to accumulate and persist in the near-surface environment. By changing atmospheric circulation and precipitation patterns, global warming could alter the meteorological factors that regulate air stagnation frequency. We analyze the response of the National Climatic Data Center (NCDC) Air Stagnation Index (ASI) to anthropogenically enhanced radiative forcing using global climate model projections of late-21(st) century climate change (SRES A1B scenario). Our results indicate that the atmospheric conditions over the highly populated, highly industrialized regions of the eastern United States, Mediterranean Europe, and eastern China are particularly sensitive to global warming, with the occurrence of stagnant conditions projected to increase 12-to-25% relative to late-20(th) century stagnation frequencies (3-18+ days/year). Changes in the position/strength of the polar jet, in the occurrence of light surface winds, and in the number of precipitation-free days all contribute to more frequent late-21(st) century air mass stagnation over these high-population regions. In addition, we find substantial inter-model spread in the simulated response of stagnation conditions over some regions using either native or bias corrected global climate model simulations, suggesting that changes in the atmospheric circulation and/or the distribution of precipitation represent important sources of uncertainty in the response of air quality to global warming. PMID:23284587

  12. Response of air stagnation frequency to anthropogenically enhanced radiative forcing

    PubMed Central

    Horton, Daniel E.; Harshvardhan; Diffenbaugh, Noah S.

    2012-01-01

    Stagnant atmospheric conditions can lead to hazardous air quality by allowing ozone and particulate matter to accumulate and persist in the near-surface environment. By changing atmospheric circulation and precipitation patterns, global warming could alter the meteorological factors that regulate air stagnation frequency. We analyze the response of the National Climatic Data Center (NCDC) Air Stagnation Index (ASI) to anthropogenically enhanced radiative forcing using global climate model projections of late-21st century climate change (SRES A1B scenario). Our results indicate that the atmospheric conditions over the highly populated, highly industrialized regions of the eastern United States, Mediterranean Europe, and eastern China are particularly sensitive to global warming, with the occurrence of stagnant conditions projected to increase 12-to-25% relative to late-20th century stagnation frequencies (3-18+ days/year). Changes in the position/strength of the polar jet, in the occurrence of light surface winds, and in the number of precipitation-free days all contribute to more frequent late-21st century air mass stagnation over these high-population regions. In addition, we find substantial inter-model spread in the simulated response of stagnation conditions over some regions using either native or bias corrected global climate model simulations, suggesting that changes in the atmospheric circulation and/or the distribution of precipitation represent important sources of uncertainty in the response of air quality to global warming. PMID:23284587

  13. Circulation system complex networks and teleconnections

    NASA Astrophysics Data System (ADS)

    Gong, Zhi-Qiang; Wang, Xiao-Juan; Zhi, Rong; Feng, Ai-Xia

    2011-07-01

    In terms of the characteristic topology parameters of climate complex networks, the spatial connection structural complexity of the circulation system and the influence of four teleconnection patterns are quantitatively described. Results of node degrees for the Northern Hemisphere (NH) mid-high latitude (30° N-90° N) circulation system (NHS) networks with and without the Arctic Oscillations (AO), the North Atlantic Oscillations (NAO) and the Pacific—North American pattern (PNA) demonstrate that the teleconnections greatly shorten the mean shortest path length of the networks, thus being advantageous to the rapid transfer of local fluctuation information over the network and to the stability of the NHS. The impact of the AO on the NHS connection structure is most important and the impact of the NAO is the next important. The PNA is a relatively independent teleconnection, and its role in the NHS is mainly manifested in the connection between the NHS and the tropical circulation system (TRS). As to the Southern Hemisphere mid-high latitude (30° S-90° S) circulation system (SHS), the impact of the Antarctic Arctic Oscillations (AAO) on the structural stability of the system is most important. In addition, there might be a stable correlation dipole (AACD) in the SHS, which also has important influence on the structure of the SHS networks.

  14. Distribution patterns, infiltration and health risk assessment of PM2.5-bound PAHs in indoor and outdoor air in cold zone.

    PubMed

    Mohammed, Mohammed O A; Song, Wei-Wei; Ma, Yong-Liang; Liu, Li-Yan; Ma, Wan-Li; Li, Wen-Long; Li, Yi-Fan; Wang, Feng-Yan; Qi, Mei-Yun; Lv, Na; Wang, Ding-Zhen; Khan, Afed Ulla

    2016-07-01

    In this study we investigated the distribution patterns, infiltration and health risk assessment of PM2.5-bound PAHs in indoor and outdoor air done in Harbin city, northeastern China. Simultaneous indoor and outdoor sampling was done to collect 264 PM2.5 samples from four sites during winter, summer, and spring. Infiltration of PAHs into indoors was estimated using Retene, Benzo [ghi]perylene and Chrysene as reference compounds, where the latter compound was suggested to be a good estimator and subsequently used for further calculation of infiltration factors (IFs). Modeling with positive matrix factorization (PMF5) and estimation of diagnostic isomeric ratios were applied for identifying sources, where coal combustion, crop residues burning and traffic being the major contributors, particularly during winter. Linear discriminant analysis (LDA) has been utilized to show the distribution patterns of individual PAH congeners. LDA showed that, the greatest seasonal variability was attributed to high molecular weight compounds (HMW PAHs). Potential health risk of PAHs exposure was assessed through relative potency factor approach (RPF). The levels of the sum of 16 US EPA priority PAHs during colder months were very high, with average values of 377 ± 228 ng m(-)(3) and 102 ± 75.8 ng m(-)(3), for the outdoors and indoors, respectively. The outdoor levels reported to be 19 times higher than the outdoor concentrations during warmer months (summer + spring), while the indoor concentrations were suggested to be 9 times and 10 times higher than that for indoor summer (average 11.73 ± 4 ng m(-3)) and indoor spring (9.5 ± 3.3 ng m(-3)). During nighttime, outdoor PAHs revealed wider range of values compared to datytime which was likely due to outdoor temperature, a weather parameter with the strongest negative influence on ∑16PAHs compared to low impact of relative humidity and wind speed. PMID:27108365

  15. Circulation and Finding System.

    ERIC Educational Resources Information Center

    Pierce, A. R.

    This report describes an online minicomputer-based system, one combining library inventory control with catalog access, that was implemented at Virginia Tech's main library in order to meet the demands of increased circulation activity and rising staff costs. Following overviews of the institutional environment, the systems development department,…

  16. Circulation Aide Training Manual.

    ERIC Educational Resources Information Center

    Bergeson, Alan O.

    This training manual provides instruction on shelving and other duties for student assistants in the learning resources center at the College of Dupage, located in Illinois. It is noted that prospective student circulation aides are required to read the manual and pass a written test on policies and procedures before they are allowed to shelve…

  17. Breathing Easy over Air Quality.

    ERIC Educational Resources Information Center

    Greim, Clifton; Turner, William

    1991-01-01

    School systems should test the air in every school building for the presence and level of contaminants such as radon and asbestos and whether the ventilation system is circulating the proper amount of air. Periodic maintenance is required for all mechanical systems. (MLF)

  18. Interannual variability in the stratospheric-tropospheric circulation in a coupled ocean-atmosphere GCM

    SciTech Connect

    Kitoh, Akio; Koide, Hiroshi; Kodera, Kunihiko

    1996-03-01

    The authors look for interannual variations in circulation patterns in the stratosphere/troposphere circulation and sea surface temperatures within the Meteorological Research Institute coupled ocean-atmosphere general circulation model. They are able to identify two modes in this model which exhibit this type of variability. One involves the stratospheric polar vortex, coupled via tropospheric circulation to SST variations. The second mode involves El Nino type phenomena coupled into the tropospheric subtropical jet.

  19. A new tool for coding and interpreting injuries in fatal airplane crashes: the crash injury pattern assessment tool application to the Air France Flight AF447 disaster (Rio de Janeiro-Paris), 1st of June 2009.

    PubMed

    Schuliar, Yves; Chapenoire, Stéphane; Miras, Alain; Contrand, Benjamin; Lagarde, Emmanuel

    2014-09-01

    For investigation of air disasters, crash reconstruction is obtained using data from flight recorders, physical evidence from the site, and injuries patterns of the victims. This article describes a new software, Crash Injury Pattern Assessment Tool (CIPAT), to code and analyze injuries. The coding system was derived from the Abbreviated Injury Score (AIS). Scores were created corresponding to the amount of energy required causing the trauma (ER), and the software was developed to compute summary variables related to the position (assigned seat) of victims. A dataset was built from the postmortem examination of 154/228 victims of the Air France disaster (June 2009), recovered from the Atlantic Ocean after a complex and difficult task at a depth of 12790 ft. The use of CIPAT allowed to precise cause and circumstances of deaths and confirmed major dynamics parameters of the crash event established by the French Civil Aviation Safety Investigation Authority.

  20. Walker circulation in a transient climate

    NASA Astrophysics Data System (ADS)

    Plesca, Elina; Grützun, Verena; Buehler, Stefan A.

    2016-04-01

    The tropical overturning circulations modulate the heat exchange across the tropics and between the tropics and the poles. The anthropogenic influence on the climate system will affect these circulations, impacting the dynamics of the Earth system. In this work we focus on the Walker circulation. We investigate its temporal and spatial dynamical changes and their link to other climate features, such as surface and sea-surface temperature patterns, El-Niño Southern Oscillation (ENSO), and ocean heat-uptake, both at global and regional scale. In order to determine the impact of anthropogenic climate change on the tropical circulation, we analyze the outputs of 28 general circulation models (GCMs) from the CMIP5 project. We use the experiment with 1% year-1 increase in CO2 concentration from pre-industrial levels to quadrupling of the concentration. Consistent with previous studies (ex. Ma and Xie 2013), we find that for this experiment most GCMs associate a weakening Walker circulation to a warming transient climate. Due to the role of the Walker Pacific cell in the meridional heat and moisture transport across the tropical Pacific and also the connection to ENSO, we find that a weakened Walker circulation correlates with more extreme El-Niño events, although without a change in their frequency. The spatial analysis of the Pacific Walker cell suggests an eastward displacement of the ascending branch, which is consistent with positive SST anomalies over the tropical Pacific and the link of the Pacific Walker cell to ENSO. Recent studies (ex. England et al. 2014) have linked a strengthened Walker circulation to stronger ocean heat uptake, especially in the western Pacific. The inter-model comparison of the correlation between Walker circulation intensity and ocean heat uptake does not convey a robust response for the investigated experiment. However, there is some evidence that a stronger weakening of the Walker circulation is linked to a higher transient climate

  1. Seasonal dynamics of circulation in Hooghly Estuary and its adjacent coastal oceans

    NASA Astrophysics Data System (ADS)

    Mishra, Shashank Kr.; Nayak, Gourav; Nayak, R. K.; Dadhwal, V. K.

    2016-05-01

    Hooghly is one of the major estuaries in Ganges, the largest and longest river in the Indian subcontinent. The Hooghly estuary is a coastal plain estuary lying approximately between 21°-23° N and 87°-89° E. We used a terrain following ocean model to study tide driven residual circulations, seasonal mean flow patterns and its energetics in the Hooghly estuary and adjacent coastal oceans on the north eastern continental shelf of India. The model is driven by tidal levels at open ocean end and winds at the air-sea interface. The sources of forcing fields for tides were from FES2012, winds from ECMWF. Harmonic analysis is carried out to compute the tidal and non-tidal components of currents and sea level from the model solutions. The de-tidal components were averaged for the entire period of simulation to describe residual and mean-seasonal circulations in the regions. We used tide-gauge, SARAL-ALTIKA along track sea level measurements to evaluate model solutions. Satellite measure Chla were used along with simulated currents to describe important features of the circulations in the region.

  2. Circulating Tumor Cells.

    PubMed

    Paoletti, Costanza; Hayes, Daniel F

    2016-01-01

    Circulating Tumor Cells (CTC) are shed from primary or secondary tumors. Prior studies have demonstrated that enumeration of CTC is a robust independent prognostic factor of progression free and overall survival in patients with early and metastatic breast cancer. CTC, as well as other circulating tumor markers, have the appealing advantages over tissue biopsy of (1) ease of collection, (2) serial evaluation, and (3) interrogation of the entire tumor burden instead of just a limited part of the tumor. Advances have been recently made in phenotyping and genotyping of CTC, which should provide insights into the predictive role of CTC for sensitivity or resistance to therapies. In addition, CTC phenotypic marker changes during the course of treatment may serve as pharmacodynamic monitoring tools. Therefore, CTC may be considered "liquid biopsies," providing prognostic and predictive clinical information as well as additional understanding of tumor heterogeneity.

  3. Ocean circulation studies

    NASA Technical Reports Server (NTRS)

    Koblinsky, C. J.

    1984-01-01

    Remotely sensed signatures of ocean surface characteristics from active and passive satellite-borne radiometers in conjunction with in situ data were utilized to examine the large scale, low frequency circulation of the world's oceans. Studies of the California Current, the Gulf of California, and the Kuroshio Extension Current in the western North Pacific were reviewed briefly. The importance of satellite oceanographic tools was emphasized.

  4. Observations of the summer Red Sea circulation

    NASA Astrophysics Data System (ADS)

    Sofianos, Sarantis S.; Johns, William E.

    2007-06-01

    Aiming at exploring and understanding the summer circulation in the Red Sea, a cruise was conducted in the basin during the summer of 2001 involving hydrographic, meteorological, and direct current observations. The most prominent feature, characteristic of the summer circulation and exchange with the Indian Ocean, is a temperature, salinity, and oxygen minimum located around a depth of 75 m at the southern end of the basin, associated with Gulf of Aden Intermediate Water inflowing from the Gulf of Aden during the summer season as an intruding subsurface layer. Stirring and mixing with ambient waters lead to marked increases in temperature (from 16.5 to almost 33°C) and salinity (from 35.7 to more than 38 psu) in this layer by the time it reaches midbasin. The observed circulation presents a very vigorous pattern with strong variability and intense features that extend the width of the basin. A permanent cyclone, detected in the northern Red Sea, verifies previous observations and modeling studies, while in the central sector of the basin a series of very strong anticyclones were observed with maximum velocities exceeding 1 m/s. The three-layer flow pattern, representative of the summer exchange between the Red Sea and the Gulf of Aden, is observed in the strait of Bab el Mandeb. In the southern part of the basin the layer flow is characterized by strong banking of the inflows and outflows against the coasts. Both surface and intermediate water masses involved in the summer Red Sea circulation present prominent spatial variability in their characteristics, indicating that the eddy field and mixing processes play an important role in the summer Red Sea circulation.

  5. Carbon dioxide, ground air and carbon cycling in Gibraltar karst

    NASA Astrophysics Data System (ADS)

    Mattey, D. P.; Atkinson, T. C.; Barker, J. A.; Fisher, R.; Latin, J.-P.; Durrell, R.; Ainsworth, M.

    2016-07-01

    We put forward a general conceptual model of CO2 behaviour in the vadose zone of karst aquifers, based on physical principles of air flow through porous media and caves, combined with a geochemical interpretation of cave monitoring data. This 'Gibraltar model' links fluxes of water, air and carbon through the soil with the porosity of the vadose zone, the circulation of ground air and the ventilation of caves. Gibraltar hosts many natural caves whose locations span the full length and vertical range of the Rock. We report results of an 8-year monitoring study of carbon in soil organic matter and bedrock carbonate, dissolved inorganic carbon in vadose waters, and gaseous CO2 in soil, cave and ground air. Results show that the regime of cave air CO2 results from the interaction of cave ventilation with a reservoir of CO2-enriched ground air held within the smaller voids of the bedrock. The pCO2 of ground air, and of vadose waters that have been in close contact with it, are determined by multiple factors that include recharge patterns, vegetation productivity and root respiration, and conversion of organic matter to CO2 within the soil, the epikarst and the whole vadose zone. Mathematical modelling and field observations show that ground air is subject to a density-driven circulation that reverses seasonally, as the difference between surface and underground temperatures reverses in sign. The Gibraltar model suggests that cave air pCO2 is not directly related to CO2 generated in the soil or the epikarstic zone, as is often assumed. Ground air CO2 formed by the decay of organic matter (OM) washed down into the deeper unsaturated zone is an important additional source of pCO2. In Gibraltar the addition of OM-derived CO2 is the dominant control on the pCO2 of ground air and the Ca-hardness of waters within the deep vadose zone. The seasonal regime of CO2 in cave air depends on the position of a cave in relation to the density-driven ground air circulation pattern which

  6. Library Circulation Systems: An Overview

    ERIC Educational Resources Information Center

    Surace, Cecily J.

    1972-01-01

    The model circulation system outlined is an on-line real time system in which the circulation file is created from the shelf list. The model extends beyond the operational limits of most existing circulation systems and can be considered a reflection of the current state of the art. (36 references) (Author/NH)

  7. AIR COOLED NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1958-05-27

    A nuclear reactor of the air-cooled, graphite moderated type is described. The active core consists of a cubicle mass of graphite, approximately 25 feet in each dimension, having horizontal channels of square cross section extending between two of the opposite faces, a plurality of cylindrical uranium slugs disposed in end to end abutting relationship within said channels providing a space in the channels through which air may be circulated, and a cadmium control rod extending within a channel provided in the moderator. Suitable shielding is provlded around the core, as are also provided a fuel element loading and discharge means, and a means to circulate air through the coolant channels through the fuel charels to cool the reactor.

  8. Variability in AIRS CO2 during active and break phases of Indian summer monsoon.

    PubMed

    Revadekar, J V; Ravi Kumar, K; Tiwari, Yogesh K; Valsala, Vinu

    2016-01-15

    Due to human activities, the atmospheric concentration of Carbon Dioxide (CO2) has been rising extensively since the Industrial Revolution. Indian summer monsoon (ISM) has a dominant westerly component from ocean to land with a strong tendency to ascend and hence may have role in CO2 distribution in lower and middle troposphere over Indian sub-continent. A substantial component of ISM variability arises from the fluctuations on the intra-seasonal scale between active and break phases which correspond to strong and weak monsoon circulation. In view of the above, an attempt is made in this study to examine the AIRS/AQUA satellite retrieved CO2 distribution in response to atmospheric circulation with focus on active and break phase. Correlation analysis indicates the increase in AIRS CO2 linked with strong monsoon circulation. Study also reveals that anomalous circulation pattern during active and break phase show resemblance with high and low values of AIRS CO2. Homogeneous monsoon regions of India show substantial increase in CO2 levels during active phase. Hilly regions of India show strong contrast in CO2 and vertical velocity during active and break phases.

  9. Circulation Control in NASA's Vehicle Systems

    NASA Technical Reports Server (NTRS)

    Rich, Paul; McKinley, Bob; Jones, Greg

    2005-01-01

    Specific to the application of any technology to a vehicle, such as circulation control, it is important to understand the process that NASA is using to set its direction in research and development. To see how circulation control fits into any given NASA program requires the reader to understand NASA's Vehicle Systems (VS) Program. The VS Program recently celebrated its first year of existence with an annual review - an opportunity to look back on accomplishments, solicit feedback, expand national advocacy and support for the program, and recognize key contributions. Since its formation last year, Vehicle Systems has coordinated seven existing entities in a streamlined aeronautics research effort. It invests in vehicle technologies to protect the environment, make air travel more accessible and affordable for Americans, enable exploration through new aerospace missions, and augment national security. This past year has seen a series of valuable partnerships with industry, academia, and government agencies to make crucial aeronautics advances and assure America s future in flight.

  10. Disinfecting Filters For Recirculated Air

    NASA Technical Reports Server (NTRS)

    Pilichi, Carmine A.

    1992-01-01

    Simple treatment disinfects air filters by killing bacteria, algae, fungi, mycobacteria, viruses, spores, and any other micro-organisms filters might harbor. Concept applied to reusable stainless-steel wire mesh filters and disposable air filters. Treatment used on filters in air-circulation systems in spacecraft, airplanes, other vehicles, and buildings to help prevent spread of colds, sore throats, and more-serious illnesses.

  11. Radiofrequency radiation alters the immune system. II. Modulation of in vivo lymphocyte circulation

    SciTech Connect

    Liburdy, R.P.

    1980-07-01

    In vivo lymphocyte circulation was significantly altered in mice exposed to whole-body radiofrequency radiation (RFR). In vivo lymphocyte circulation was followed by quantitating activity of sodium chromate-51-labeled lymphocytes in the lung, spleen, liver, and bone marrow of animals at different times after iv spleen lymphocyte injection. Immediately after cell injection, animals were exposed to 2.6-GHz RFR (CW) at 25 or 5 mW/cm/sup 2/ (3.8 W/kg) for 1 h. At 1,6, and 24 h aftr lymphocyte injection target organs were removed, weighed, and counted. Sham RFR, warm-air, and steroid-treated groups were included as controls. Hyperthermic RFR exposure (25 mW/cm/sup 2/, 2.0/sup 0/C increase in core temperature) led to a 37% reduction in lymphocytes leaving the lung to migrate into the spleen. In addition, a threefold increse in spleen lymphocytes entering the bone marrow occurred. Significantly, this pattern was also observed in the steroid-treated group; nonthermogenic RFR exposure (5 mWcm/sup 2/) and warm-air exposures did not lead to altered lymphocyte traffic. These results support the idea that steroid release associated with thermal stress and the process of thermoregulation is a significant operatnt factor responsible for RFR effects on the immune system.

  12. Effects of latent heating on driving atmospheric circulation of brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Latent heating from condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal atmospheric conditions of BDs (hot and thus with relatively short radiative timescale), latent heating alone by silicate vapor is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with relatively long radiative timescale, which may be the case for cooler bodies, tend to maintain an active hydrological cycle and develop zonal jets. Once condensation happens, storms driven by

  13. Subtropical circulation, Tibetan Plateau, and Asian Summer Monsoon

    NASA Astrophysics Data System (ADS)

    Wu, G. X.

    2015-12-01

    The characteristics of the land-air-sea interaction in summer subtropics and their impacts on climate were revealed. It was shown that different kind of diabatic heating plays different roles in the formation of the subtropical circulation where the surface sensible heating associated with the land-sea distribution plays a fundamentally important role, and the three spatial- scales of atmospheric forcing contribute in various ways to the formation of aridity/desert over the western parts of continents and wet/monsoon over the eastern parts. Thus monsoon and desert coexist as twin features. It was identified that the onset of the Asian summer monsoon (ASM) consists of three dynamically consequential stages: the onset first occurs over the eastern Bay of Bengal (BOB) in early May, which is followed by the onset over the South China Sea in mid-May, and the Indian Monsoon onset in early June. During such an onset progression, the formation, maintenance and evolution of the South Asian High (SAH) play a significant role in generating the upper tropospheric dumping. In the lower troposphere, the development of the BOB monsoon onset vortex, the ASM onset barrier, the cross equatorial SST gradient and the forced convection over the eastern Arabian Sea also regulate the onset evolution. In winter the Tibetan Plateau (TP) can inspire a stationary dipole-type atmospheric wave, forming a specific climate pattern in Asia. In spring, such a dipole circulation forms the unique persistent rainfall over Southern China. The TP forcing can also anchor the ASM onset over the BOB by generating the unique short- life BOB SST warm pool and modulating the SAH in the upper troposphere. In summer the thermal forcing of the Tibetan-Iranian Plateau plays a significant role in controlling the Asian monsoon by transporting water vapor from the sea to the land for the genesis of continental monsoon. The TP thermal forcing also modulates the regional climate variability in different time scales.

  14. Climate predictability experiments with a general circulation model

    NASA Astrophysics Data System (ADS)

    Bengtsson, L.; Arpe, K.; Roeckner, E.; Schulzweida, U.

    1996-03-01

    The atmospheric response to the evolution of the global sea surface temperatures from 1979 to 1992 is studied using the Max-Planck-Institut 19 level atmospheric general circulation model, ECHAM3 at T 42 resolution. Five separate 14-year integrations are performed and results are presented for each individual realization and for the ensemble-averaged response. The results are compared to a 30-year control integration using a climate monthly mean state of the sea surface temperatures and to analysis data. It is found that the ECHAM3 model, by and large, does reproduce the observed response pattern to El Nino and La Niña. During the El Nino events, the subtropical jet streams in both hemispheres are intensified and displaced equatorward, and there is a tendency towards weak upper easterlies over the equator. The Southern Oscillation is a very stable feature of the integrations and is accurately reproduced in all experiments. The inter-annual variability at middle- and high-latitudes, on the other hand, is strongly dominated by chaotic dynamics, and the tropical SST forcing only modulates the atmospheric circulation. The potential predictability of the model is investigated for six different regions. Signal to noise ratio is large in most parts of the tropical belt, of medium strength in the western hemisphere and generally small over the European area. The ENSO signal is most pronounced during the boreal spring. A particularly strong signal in the precipitation field in the extratropics during spring can be found over the southern United States. Western Canada is normally warmer during the warm ENSO phase, while northern Europe is warmer than normal during the ENSO cold phase. The reason is advection of warm air due to a more intense Pacific low than normal during the warm ENSO phase and a more intense Icelandic low than normal during the cold ENSO phase, respectively.

  15. Monitoring coastal water properties and current circulation with ERTS-1

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Otley, M.; Wethe, C.; Rogers, R. H.

    1977-01-01

    Imagery and digital tapes from nine successful ERTS-1 passes over Delaware Bay during different portions of the tidal cycle were analyzed with special emphasis on turbidity, current circulation, waste disposal plumes, and convergent boundaries between different water masses. ERTS-1 image radiance correlated well with Secchi depth and suspended sediment concentration. Circulation patterns observed by ERTS-1 during different parts of the tidal cycle, agreed well with predicted and measured currents throughout Delaware Bay.

  16. The main characteristics of atmospheric circulation associated with fog in Greece

    NASA Astrophysics Data System (ADS)

    Houssos, E. E.; Lolis, C. J.; Bartzokas, A.

    2009-11-01

    The characteristics of the atmospheric circulation over Europe and the Mediterranean associated with the formation and the dissipation of fog in Greece are examined. The data used consists of: i) 3-hourly meteorological observations recorded at 16 meteorological stations in Greece and ii) daily (00:00 UTC) 2.5×2.5 grid point values of mean sea-level pressure, 500 hPa geopotential height, 850 hPa and 500 hPa air temperatures and 1000-500 hPa thickness over Europe for the period 1957-2002. 1055 fog events are extracted from the 3-hourly meteorological observations. A specific methodology scheme including S-mode Factor Analysis and k-means Cluster Analysis is applied to the grid point data sets for the first day of a fog event (D day), the day prior to D day (D-1 day) and the day that follows the last day of a fog event (END day) and the 1055 evolutions of the atmospheric circulation associated with fog events in Greece are classified into 10 clusters. The mean patterns of MSL Pressure, 850 hPa and 500 hPa air temperatures, 1000-500 hPa thickness and 500 hPa geopotential height show that in most of the clusters, the presence of anticyclonic conditions over the Balkans, a warm front passage, or a weak, humid southerly flow induced by the presence of a shallow depression over the western Mediterranean favor fog formation in Greece, while the dissipation of fog occurs when drier air masses are transferred over the Balkans. The main differences among the 10 clusters refer to the exact position, the intensity and the specific evolution of the surface and the upper air systems, the season of their predominance and the area of the Greek territory that mainly refer to.

  17. Climate modelling: Northern Hemisphere circulation.

    PubMed

    Gillett, Nathan P

    2005-09-22

    Air pressure at sea level during winter has decreased over the Arctic and increased in the Northern Hemisphere subtropics in recent decades, a change that has been associated with 50% of the Eurasian winter warming observed over the past 30 years, with 60% of the rainfall increase in Scotland and with 60% of the rainfall decrease in Spain. This trend is inconsistent with the simulated response to greenhouse-gas and sulphate-aerosol changes, but it has been proposed that other climate influences--such as ozone depletion--could account for the discrepancy. Here I compare observed Northern Hemisphere sea-level pressure trends with those simulated in response to all the major human and natural climate influences in nine state-of-the-art coupled climate models over the past 50 years. I find that these models all underestimate the circulation trend. This inconsistency suggests that we cannot yet simulate changes in this important property of the climate system or accurately predict regional climate changes.

  18. Modelled Circulation In Storfjorden

    NASA Astrophysics Data System (ADS)

    Skogseth, R.; Asplin, L.

    The model area Storfjorden is situated between the islands Spitsbergen, Barentsöya and Edgeöya at the Svalbard Archipelago. The entrance of Storfjorden is defined by a shallow bank Storfjordbanken and some small islands Tusenöyane in southeast, and by an 115m deep sill at about 76 45' N in the south. Maximum depth in Storfjorden is 190m, which is surrounded by gradually shallower shelves in the north, the east and southeast. A steep bottom slope is present on the western side of Storfjorden. He- leysundet and Freemansundet, two sounds between respectively Spitsbergen and Bar- entsöya, and Barentsöya and Edgeöya, define two narrow and shallow entrances in the north and northeast connecting Storfjorden with the northwestern Barents Sea. Strong tidal currents exist in Heleysundet (4-5ms-1) and Freemansundet (2-3ms-1), but the general circulation in Storfjorden is not well known. The coastal current in Storfjor- den is cyclonic directed into Storfjorden south of Edgeöya from the East Spitsbergen Current and out of Storfjorden south of Spitsbergen where it is called Sørkappstrøm- men. A three-dimensional sigma layered numerical ocean model called Bergen Ocean Model (BOM) was used to simulate the circulation in Storfjorden with Freemansundet opened. Two simulations were carried out, one with heat flux (100 Wm-2) and one without heat flux from the ocean to the atmosphere. The heat flux was applied only in the proper fjord area north of the sill and not outside as a crude approximation of the effects of a polynya in the sea ice cover during winter. Both simulations had a 4km horizontal resolution and 21 sigma layers. The model is forced by winds (from the NCEP reanalyzed fields) and tides. Initial fields are from the DNMI/IMR climatol- ogy. The model simulation without heat flux gave a circulation heavily dependent on tidal forcing, showing strong tidal currents up to 2ms-1 in Freemansundet, between Tusenöyane and on Storfjordbanken southwest of Edgeöya. Earlier

  19. World Ocean Circulation Experiment

    NASA Technical Reports Server (NTRS)

    Clarke, R. Allyn

    1992-01-01

    The oceans are an equal partner with the atmosphere in the global climate system. The World Ocean Circulation Experiment is presently being implemented to improve ocean models that are useful for climate prediction both by encouraging more model development but more importantly by providing quality data sets that can be used to force or to validate such models. WOCE is the first oceanographic experiment that plans to generate and to use multiparameter global ocean data sets. In order for WOCE to succeed, oceanographers must establish and learn to use more effective methods of assembling, quality controlling, manipulating and distributing oceanographic data.

  20. Air-water centrifugal convection

    NASA Astrophysics Data System (ADS)

    Herrada, Miguel; Shtern, Vladimir

    2014-07-01

    A sealed cylindrical container is filled with air and water. The container rotation and the axial gradient of temperature induce the steady axisymmetric meridional circulation of both fluids due to the thermal buoyancy and surface-tension (Marangoni) effects. If the temperature gradient is small, the water circulation is one-cellular while the air circulation can be one- or two-cellular depending on water fraction Wf. The numerical simulations are performed for the cylinder length-to-radius ratio l = 1 and l = 4. The l = 4 results and the analytical solution for l → ∞ agree in the cylinder's middle part. As the temperature gradient increases, the water circulation becomes one-, two-, or three-cellular depending on Wf. The results are of fundamental interest and can be applied for bioreactors.

  1. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    SciTech Connect

    Keith, Raymond E.; Heller, Thomas J.; Bush, Stuart A.

    1991-01-01

    This Annual Report on Colorado-Ute Electric Association's NUCLA Circulating Fluidized Bed (CFB) Demonstration Program covers the period from February 1987 through December 1988. The outline for presentation in this report includes a summary of unit operations along with individual sections covering progress in study plan areas that commenced during this reporting period. These include cold-mode shakedown and calibration, plant commercial performance statistics, unit start-up (cold), coal and limestone preparation and handling, ash handling system performance and operating experience, tubular air heater, baghouse operation and performance, materials monitoring, and reliability monitoring. During this reporting period, the coal-mode shakedown and calibration plan was completed. (VC)

  2. Seasonal overturning circulation in the Red Sea: 1. Model validation and summer circulation

    NASA Astrophysics Data System (ADS)

    Yao, Fengchao; Hoteit, Ibrahim; Pratt, Larry J.; Bower, Amy S.; Zhai, Ping; Köhl, Armin; Gopalakrishnan, Ganesh

    2014-04-01

    The overturning circulation in the Red Sea exhibits a distinct seasonally reversing pattern and is studied using high-resolution MIT general circulation model simulations. In the first part of this study, the vertical and horizontal structure of the summer overturning circulation and its dynamical mechanisms are presented from the model results. The seasonal water exchange in the Strait of Bab el Mandeb is successfully simulated, and the structures of the intruding subsurface Gulf of Aden intermediate water are in good agreement with summer observations in 2011. The model results suggest that the summer overturning circulation is driven by the combined effect of the shoaling of the thermocline in the Gulf of Aden resulting from remote winds in the Arabian Sea and an upward surface slope from the Red Sea to the Gulf of Aden set up by local surface winds in the Red Sea. In addition, during late summer two processes associated, respectively, with latitudinally differential heating and increased salinity in the southern Red Sea act together to cause the reversal of the contrast of the vertical density structure and the cessation of the summer overturning circulation. Dynamically, the subsurface northward pressure gradient force is mainly balanced by vertical viscosity resulting from the vertical shear and boundary friction in the Strait of Bab el Mandeb. Unlike some previous studies, the three-layer summer exchange flows in the Strait of Bab el Mandeb do not appear to be hydraulically controlled.

  3. North Atlantic Circulation

    NASA Astrophysics Data System (ADS)

    Molinari, R.; Bryan, K.; Schott, F.

    The intensity of the North Atlantic winddriven and thermohaline circulation and the close proximity of many oceanographic installations make the North Atlantic a particularly favored region of the world ocean from the standpoint of research in ocean circulation. Recent increases in available data and advances in numerical modeling techniques served as the impetus to convene a joint workshop of modelers and observers working on the North Atlantic with the Scientific Committee on Oceanic Research (SCOR) Working Group (WG) 68 (“North Atlantic Circulation”). Goals of the workshop were to provide an update on data sets and models and to discuss the poleward heat flux problem and possible monitoring strategies. The joint Workshop/SCOR WG-68 meeting was convened by F. Schott (chairman of the working group; Rosenstiel School of Marine and Atmospheric Science, Miami, Fla.), K. Bryan (National Oceanic and Atmospheric Administration/ Geophysical Fluid Dynamics Laboratory (NOAA/GFDL)), and R. Molinari (NOAA/Atlantic Oceanographic and Meteorological Laboratory (NOAA/AOML)).

  4. Circulation of Stars

    NASA Astrophysics Data System (ADS)

    Boitani, P.

    2016-01-01

    Since the dawn of man, contemplation of the stars has been a primary impulse in human beings, who proliferated their knowledge of the stars all over the world. Aristotle sees this as the product of primeval and perennial “wonder” which gives rise to what we call science, philosophy, and poetry. Astronomy, astrology, and star art (painting, architecture, literature, and music) go hand in hand through millennia in all cultures of the planet (and all use catasterisms to explain certain phenomena). Some of these developments are independent of each other, i.e., they take place in one culture independently of others. Some, on the other hand, are the product of the “circulation of stars.” There are two ways of looking at this. One seeks out forms, the other concentrates on the passing of specific lore from one area to another through time. The former relies on archetypes (for instance, with catasterism), the latter constitutes a historical process. In this paper I present some of the surprising ways in which the circulation of stars has occurred—from East to West, from East to the Far East, and from West to East, at times simultaneously.

  5. Hemorheology and circulation.

    PubMed

    Marossy, A; Svorc, P; Kron, I; Gresová, S

    2009-01-01

    The main functions of the blood are the transport, and delivery of oxygen and nutrients, removal of carbon dioxide and waste products of metabolism, distribution of heat and signals of immune system. They are provided by circulation due to the driving force of the heart. Circulation of the blood depends on its rheological properties of the blood as well as on characteristics of the vessels through which the blood passes. The blood flow resistance is influenced by the complicated architecture of the vascular network and flow behaviour of blood components - blood cells and plasma. The obtained data based on analysis of influences on blood flow are differentiated in the dependence on place and level of investigation. At a macroscopic level the blood appears to be a liquid material, but at a microscopic level the blood appears to be a material with microscopic solid particles of varying size - various blood cells. From this point of view, we have to consider the blood flow in large vessels, and also on the level of microvessels. This division of facts of hemorheology is somewhat simplistic, but is very useful from the point of view of explanation and comprehension. PMID:19628890

  6. High-Resolution Dynamical Downscaling of ERA-Interim Using the WRF Regional Climate Model for the Area of Poland. Part 2: Model Performance with Respect to Automatically Derived Circulation Types

    NASA Astrophysics Data System (ADS)

    Ojrzyńska, Hanna; Kryza, Maciej; Wałaszek, Kinga; Szymanowski, Mariusz; Werner, Małgorzata; Dore, Anthony J.

    2016-03-01

    This paper presents the application of the high-resolution WRF model data for the automatic classification of the atmospheric circulation types and the evaluation of the model results for daily rainfall and air temperatures. The WRF model evaluation is performed by comparison with measurements and gridded data (E-OBS). The study is focused on the area of Poland and covers the 1981-2010 period, for which the WRF model has been run using three nested domains with spatial resolution of 45 km × 45 km, 15 km × 15 km and 5 km × 5 km. For the model evaluation, we have used the data from the innermost domain, and data from the second domain were used for circulation typology. According to the circulation type analysis, the anticyclonic types (AAD and AAW) are the most frequent. The WRF model is able to reproduce the daily air temperatures and the error statistics are better, compared with the interpolation-based gridded dataset. The high-resolution WRF model shows a higher spatial variability of both air temperature and rainfall, compared with the E-OBS dataset. For the rainfall, the WRF model, in general, overestimates the measured values. The model performance shows a seasonal pattern and is also dependent on the atmospheric circulation type, especially for daily rainfall.

  7. Influence of local circulations on wind, moisture, and precipitation close to Manaus City, Amazon Region, Brazil

    NASA Astrophysics Data System (ADS)

    Santos, Mercel J.; Silva Dias, Maria A. F.; Freitas, Edmilson D.

    2014-12-01

    This paper presents long-term-derived local wind patterns as well as their role on moisture transport and on spatial/temporal distribution of precipitation close to Manaus City region. In this analysis we used surface weather station data and rainfall estimates from TRMM (Tropical Rainfall Measuring Mission) and CMORPH (Climate Prediction Center morphing method). The weather stations promoted information of wind direction and dew point temperature, used here as atmospheric moisture indicator. The 3-hourly average of accumulated precipitation, calculated using satellite estimates (TRMM and CMORPH), allowed to assess the spatial distribution of the rainfall diurnal cycle and how it is modulated by the local circulations. The station data results show that in the daytime, between 9:00 and 18:00 local time, winds away from the rivers are frequent, indicating action of the river breeze. This wind condition transports moist air from the rivers to the Manaus City. Winds toward rivers are commonly observed at night and in the morning, mostly at Ponta Pelada airport station, and are evidence of the land breeze occurrence. These local winds transport drier air from Manaus City to the river regions, as verified at Ponta Pelada station. The evidence of the local circulations and their impact on the moisture transport are more obvious in the dry season. The rainfall diurnal cycle has a spatial tendency varying according to the hour of the day. In the afternoon and in the evening, maximum precipitation values are observed over land, whereas reduced rainfall values are verified over rivers. At dawn and in the morning, the maximum values of accumulated precipitation are found over the rivers, mainly over and around the Amazon River. This rainfall spatial distribution is very likely modulated by local circulations and is much more evident in the rainiest quarter (March-May).

  8. How Circulation of Water Affects Freezing in Ponds

    ERIC Educational Resources Information Center

    Moreau, Theresa; Lamontagne, Robert; Letzring, Daniel

    2007-01-01

    One means of preventing the top of a pond from freezing involves running a circulating pump near the bottom to agitate the surface and expose it to air throughout the winter months. This phenomenon is similar to that of the flowing of streams in subzero temperatures and to the running of taps to prevent pipe bursts in winter. All of these cases…

  9. Air Pollution

    PubMed Central

    Clifton, Marjorie

    1964-01-01

    Dr Marjorie Clifton describes the classification of gaseous and nongaseous constituents of air pollution and then outlines the methods of measuring these. The National Survey embraced 150 towns of all sizes throughout England and Wales and provided data on smoke and sulphur dioxide in relation to climate, topography, industrialization, population density, fuel utilization and urban development. Dr W C Turner discusses the relationship between air pollution and mortality from respiratory conditions, and particularly the incidence of chronic bronchitis. He postulates a theory that such respiratory conditions arise as an allergy to the spores of certain moulds, spore formation being encouraged by the air humidity in Greatv Britain and overcrowded and damp living conditions. He describes the results of a twenty-week study undertaken in 1962-3, showing associations between respiratory disease and levels of air pollution. Dr Stuart Carne undertook a survey in general practice to plot the patterns of respiratory illness in London during the winter of 1962-3. There were two peaks of respiratory illnesses coinciding with the fog at the beginning of December and the freeze-up from the end of December until the beginning of March. PMID:14178955

  10. Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing.

    PubMed

    Vecchi, Gabriel A; Soden, Brian J; Wittenberg, Andrew T; Held, Isaac M; Leetmaa, Ants; Harrison, Matthew J

    2006-05-01

    Since the mid-nineteenth century the Earth's surface has warmed, and models indicate that human activities have caused part of the warming by altering the radiative balance of the atmosphere. Simple theories suggest that global warming will reduce the strength of the mean tropical atmospheric circulation. An important aspect of this tropical circulation is a large-scale zonal (east-west) overturning of air across the equatorial Pacific Ocean--driven by convection to the west and subsidence to the east--known as the Walker circulation. Here we explore changes in tropical Pacific circulation since the mid-nineteenth century using observations and a suite of global climate model experiments. Observed Indo-Pacific sea level pressure reveals a weakening of the Walker circulation. The size of this trend is consistent with theoretical predictions, is accurately reproduced by climate model simulations and, within the climate models, is largely due to anthropogenic forcing. The climate model indicates that the weakened surface winds have altered the thermal structure and circulation of the tropical Pacific Ocean. These results support model projections of further weakening of tropical atmospheric circulation during the twenty-first century.

  11. Air-temperature variations and ENSO effects in Indonesia, the Philippines and El Salvador. ENSO patterns and changes from 1866-1993

    NASA Astrophysics Data System (ADS)

    Harger, J. R. E.

    The major features in development of the "El Nino-Southern Oscillation" (ENSO) involve oscillation of the Pacific ocean-atmosphere in an essentially unpredictable (chaotic) fashion. The system moves between extremes of the so-called "warm events" lasting one or two years and involving movement of warm sea water from the western Pacific along the equator to impact on the west coast of the American continent and "cold-events" associated with easterly trade-wind-induced flows of colder water from the eastern Pacific towards the west. Historical data indicate that ENSO years as experienced by the Island of Java are either much warmer than non-ENSO years or only slightly, if at all, warmer than normal (non-ENSO) years. Hot-dry years within the ENSO warm event cycle are almost always followed by cooler wet years and vice versa. This pattern also extends to include the year immediately following the terminal year of an ENSO warm event set. The initial year of an ENSO warm event set may be either hot with a long dry season or relatively cool (nearer to the temperature of a non-ENSO year) and having a short dry season. In recent years, since 1950, of the 9 ENSO warm events, the initial year tends to have been hot and dry for 6 (1951, 1957, 1963, 1972, 1982, 1991) and neutral or cool and wet for 3 (1968, 1976, 1986). An area of 88,000 ha burned in 1991 (Jakarta Post 30 November 1991) largely in Kalimantan in association with the 1991-1992 ENSO event, an extensive pall of smoke developed over Kalimantan, Singapore and Malaysia during September-October of 1991. Surface vegetation-based fires continued to burn in East Kalimantan as of 29 April 1992 and extended into the 1992 dry season, in response to the ENSO conditions carrying forward from 1991. The increasing annual trend in air-temperature exhibited by the mean monthly values over the period 1866-1993, for the Jakarta and the Semarang data taken together is 1.64°C (0.0132°C per year from 25.771 to 27.409°C). The major

  12. Labour circulation and the village economy in Fiji.

    PubMed

    Sofer, M

    1992-12-01

    The author examines circular labor migration in Fiji. "This paper is organized into five sections. The first section provides a brief discussion of two major perspectives of labour circulation in developing countries. The second section presents the state of the Fijian village in the context of the current pattern of uneven development in Fiji. The practice of labour circulation by Fijian villagers is dealt with in the third section. In the last two sections, issues concerning the maintenance of the polarized pattern and the preservation of the village mode of production are discussed."

  13. Anatomy of diaphragmatic circulation.

    PubMed

    Comtois, A; Gorczyca, W; Grassino, A

    1987-01-01

    The diaphragmatic circulation was studied in 48 mongrel dogs weighing 10-35 kg by injecting acrylic coloring into the arteries and veins of the diaphragm. The phrenic arteries and internal mammary arteries were found to anastomose head to head, forming an internal arterial circle around the medial leaflet of the diaphragm tendon. This arterial circle emitted vascular branches that traveled between muscle fibers toward the periphery of the diaphragm. These branches anastomosed with vessels of the intercostal arteries to form costophrenic arcades all along the fibers of the crural and costal diaphragms. The intercostal arteries were anastomosed to one another by small vessels within the muscular diaphragm, thus forming an arterial ring around the insertions of the diaphragm on the ribs. The venous drainage has an anatomic distribution similar to that observed on the arterial side, but with the additional presence of valves that could play a role in directing blood flow.

  14. Hallaran's circulating swing.

    PubMed

    Breathnach, Caoimhghin S

    2010-03-01

    William Saunders Hallaran (c.1765-1825) was physician superintendent at the County and City of Cork Lunatic Asylum for 40 years, where he distinguished between mental insanity and organic (systemic) delirium. In treatment he used emetics and purgatives, digitalis and opium, the shower bath and exercise, and argued that patients should be saved from 'unavoidable sloth' by mental as well as manual occupation. However, it is as an exponent of the circulating swing, proposed by Erasmus Darwin and used by Joseph Cox, that he is remembered. His best results were achieved, as he recorded in An Enquiry in 1810, by inducing sleep in mania of recent onset, but perhaps his most enduring observation was that some of his patients enjoyed the rotatory experience, and he had enough sense to allow the use of the swing as a mode of amusement.

  15. Ocean General Circulation Models

    SciTech Connect

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  16. Lost Circulation Technology Development Status

    SciTech Connect

    Glowka, David A.; Schafer, Diane M.; Loeppke, Glen E.; Scott, Douglas D.; Wernig, Marcus D.; Wright, Elton K.

    1992-03-24

    Lost circulation is the loss of drilling fluid from the wellbore to fractures or pores in the rock formation. In geothermal drilling, lost circulation is often a serious problem that contributes greatly to the cost of the average geothermal well. The Lost Circulation Technology Development Program is sponsored at Sandia National Laboratories by the U.S. Department of Energy. The goal of the program is to reduce lost circulation costs by 30-50% through the development of mitigation and characterization technology. This paper describes the technical progress made in this program during the period April, 1991-March, 1992.

  17. PULMONARY CIRCULATION AT EXERCISE

    PubMed Central

    NAEIJE, R; CHESLER, N

    2012-01-01

    The pulmonary circulation is a high flow and low pressure circuit, with an average resistance of 1 mmHg.min.L−1 in young adults, increasing to 2.5 mmHg.min.L−1 over 4–6 decades of life. Pulmonary vascular mechanics at exercise are best described by distensible models. Exercise does not appear to affect the time constant of the pulmonary circulation or the longitudinal distribution of resistances. Very high flows are associated with high capillary pressures, up to a 20–25 mmHg threshold associated with interstitial lung edema and altered ventilation/perfusion relationships. Pulmonary artery pressures of 40–50 mmHg, which can be achieved at maximal exercise, may correspond to the extreme of tolerable right ventricular afterload. Distension of capillaries that decrease resistance may be of adaptative value during exercise, but this is limited by hypoxemia from altered diffusion/perfusion relationships. Exercise in hypoxia is associated with higher pulmonary vascular pressures and lower maximal cardiac output, with increased likelihood of right ventricular function limitation and altered gas exchange by interstitial lung edema. Pharmacological interventions aimed at the reduction of pulmonary vascular tone have little effect on pulmonary vascular pressure-flow relationships in normoxia, but may decrease resistance in hypoxia, unloading the right ventricle and thereby improving exercise capacity. Exercise in patients with pulmonary hypertension is associated with sharp increases in pulmonary artery pressure and a right ventricular limitation of aerobic capacity. Exercise stress testing to determine multipoint pulmonary vascular pressures-flow relationships may uncover early stage pulmonary vascular disease. PMID:23105961

  18. Discriminatory Air Pollution

    ERIC Educational Resources Information Center

    McCaull, Julian

    1976-01-01

    Described are the patterns of air pollution in certain large urban areas. Persons in poverty, in occupations below the management or professional level, in low-rent districts, and in black population are most heavily exposed to air pollution. Pollution paradoxically is largely produced by high energy consuming middle-and upper-class households.…

  19. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the ma...

  20. Circulation in gas-slurry column reactors

    SciTech Connect

    Clark, N.; Kuhlman, J.; Celik, I.; Gross, R.; Nebiolo, E.; Wang, Yi-Zun.

    1990-08-15

    Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.

  1. Broad Range of Hepatitis B Virus (HBV) Patterns, Dual Circulation of Quasi-Subgenotype A3 and HBV/E and Heterogeneous HBV Mutations in HIV-Positive Patients in Gabon.

    PubMed

    Bivigou-Mboumba, Berthold; François-Souquière, Sandrine; Deleplancque, Luc; Sica, Jeanne; Mouinga-Ondémé, Augustin; Amougou-Atsama, Marie; Chaix, Marie-Laure; Njouom, Richard; Rouet, François

    2016-01-01

    Integrated data on hepatitis B virus (HBV) patterns, HBV genotypes and mutations are lacking in human immunodeficiency virus type 1 (HIV-1) co-infected patients from Africa. This survey was conducted in 2010-2013 among 762 HIV-1-positive adults from Gabon who were predominantly treated with 3TC-based antiretroviral treatment. HBV patterns were identified using immunoassays detecting total antibody to hepatitis B core antigen (HBcAb), hepatitis B surface antigen (HBsAg), IgM HBcAb, hepatitis B e antigen (HBeAg), antibody to HBsAg (HBsAb) and an in-house real-time PCR test for HBV DNA quantification. Occult hepatitis B (OBI) was defined by the presence of isolated anti-HBc with detectable serum HBV DNA. HBV genotypes and HBV mutations were analyzed by PCR-direct sequencing method. Seventy-one (9.3%) patients tested positive for HBsAg, including one with acute hepatitis B (0.1%; 95% CI, 0.0%-0.2%), nine with HBeAg-positive chronic hepatitis B (CHB) (1.2%; 95% CI, 0.6%-2.2%), 16 with HBeAg-negative CHB (2.1%; 95% CI, 1.2%-3.3%) and 45 inactive HBV carriers (5.9%; 95% CI, 4.4%-7.8%). Sixty-one (8.0%; 95% CI, 6.2%-10.1%) patients showed OBI. Treated patients showed similar HBV DNA levels to those obtained in untreated patients, regardless of HBV patterns. Around 15.0% of OBI patients showed high (>1,000 UI/mL) viremia. The mutation M204V/I conferring resistance to 3TC was more common in HBV/A (47.4%) than in HBV/E isolates (0%) (P = .04). Our findings encouraged clinicians to promote HBV vaccination in patients with no exposure to HBV and to switch 3TC to universal TDF in those with CHB.

  2. Broad Range of Hepatitis B Virus (HBV) Patterns, Dual Circulation of Quasi-Subgenotype A3 and HBV/E and Heterogeneous HBV Mutations in HIV-Positive Patients in Gabon

    PubMed Central

    Bivigou-Mboumba, Berthold; François-Souquière, Sandrine; Deleplancque, Luc; Sica, Jeanne; Mouinga-Ondémé, Augustin; Amougou-Atsama, Marie; Chaix, Marie-Laure; Njouom, Richard; Rouet, François

    2016-01-01

    Integrated data on hepatitis B virus (HBV) patterns, HBV genotypes and mutations are lacking in human immunodeficiency virus type 1 (HIV-1) co-infected patients from Africa. This survey was conducted in 2010–2013 among 762 HIV-1-positive adults from Gabon who were predominantly treated with 3TC-based antiretroviral treatment. HBV patterns were identified using immunoassays detecting total antibody to hepatitis B core antigen (HBcAb), hepatitis B surface antigen (HBsAg), IgM HBcAb, hepatitis B e antigen (HBeAg), antibody to HBsAg (HBsAb) and an in-house real-time PCR test for HBV DNA quantification. Occult hepatitis B (OBI) was defined by the presence of isolated anti-HBc with detectable serum HBV DNA. HBV genotypes and HBV mutations were analyzed by PCR-direct sequencing method. Seventy-one (9.3%) patients tested positive for HBsAg, including one with acute hepatitis B (0.1%; 95% CI, 0.0%-0.2%), nine with HBeAg-positive chronic hepatitis B (CHB) (1.2%; 95% CI, 0.6%–2.2%), 16 with HBeAg-negative CHB (2.1%; 95% CI, 1.2%–3.3%) and 45 inactive HBV carriers (5.9%; 95% CI, 4.4%–7.8%). Sixty-one (8.0%; 95% CI, 6.2%–10.1%) patients showed OBI. Treated patients showed similar HBV DNA levels to those obtained in untreated patients, regardless of HBV patterns. Around 15.0% of OBI patients showed high (>1,000 UI/mL) viremia. The mutation M204V/I conferring resistance to 3TC was more common in HBV/A (47.4%) than in HBV/E isolates (0%) (P = .04). Our findings encouraged clinicians to promote HBV vaccination in patients with no exposure to HBV and to switch 3TC to universal TDF in those with CHB. PMID:26764909

  3. Broad Range of Hepatitis B Virus (HBV) Patterns, Dual Circulation of Quasi-Subgenotype A3 and HBV/E and Heterogeneous HBV Mutations in HIV-Positive Patients in Gabon.

    PubMed

    Bivigou-Mboumba, Berthold; François-Souquière, Sandrine; Deleplancque, Luc; Sica, Jeanne; Mouinga-Ondémé, Augustin; Amougou-Atsama, Marie; Chaix, Marie-Laure; Njouom, Richard; Rouet, François

    2016-01-01

    Integrated data on hepatitis B virus (HBV) patterns, HBV genotypes and mutations are lacking in human immunodeficiency virus type 1 (HIV-1) co-infected patients from Africa. This survey was conducted in 2010-2013 among 762 HIV-1-positive adults from Gabon who were predominantly treated with 3TC-based antiretroviral treatment. HBV patterns were identified using immunoassays detecting total antibody to hepatitis B core antigen (HBcAb), hepatitis B surface antigen (HBsAg), IgM HBcAb, hepatitis B e antigen (HBeAg), antibody to HBsAg (HBsAb) and an in-house real-time PCR test for HBV DNA quantification. Occult hepatitis B (OBI) was defined by the presence of isolated anti-HBc with detectable serum HBV DNA. HBV genotypes and HBV mutations were analyzed by PCR-direct sequencing method. Seventy-one (9.3%) patients tested positive for HBsAg, including one with acute hepatitis B (0.1%; 95% CI, 0.0%-0.2%), nine with HBeAg-positive chronic hepatitis B (CHB) (1.2%; 95% CI, 0.6%-2.2%), 16 with HBeAg-negative CHB (2.1%; 95% CI, 1.2%-3.3%) and 45 inactive HBV carriers (5.9%; 95% CI, 4.4%-7.8%). Sixty-one (8.0%; 95% CI, 6.2%-10.1%) patients showed OBI. Treated patients showed similar HBV DNA levels to those obtained in untreated patients, regardless of HBV patterns. Around 15.0% of OBI patients showed high (>1,000 UI/mL) viremia. The mutation M204V/I conferring resistance to 3TC was more common in HBV/A (47.4%) than in HBV/E isolates (0%) (P = .04). Our findings encouraged clinicians to promote HBV vaccination in patients with no exposure to HBV and to switch 3TC to universal TDF in those with CHB. PMID:26764909

  4. The Role of Anthropogenic Aerosol in Atmospheric Circulation Changes

    NASA Astrophysics Data System (ADS)

    Wilcox, L.; Polvani, L. M.; Highwood, E.

    2015-12-01

    Changes in atmospheric circulation patterns play a dominant role in determining the impacts of a changing climate at the continental scale. Using CMIP5 single forcing experiments from an ensemble of models that provided anthropogenic aerosol only simulations to the archive, we quantify the influence of anthropogenic aerosol on several aspects of the atmospheric circulation, including tropical width, jet position, and jet strength. We show that there is a robust circulation response to anthropogenic aerosol in the mid twentieth century, induced by the large increases in emissions at that time. Although most anthropogenic aerosol is found in the Northern Hemisphere, a response is found in both the Northern and Southern hemispheres. We investigate the extent to which diversity in the temperature and circulation responses to aerosol are related to diversity in aerosol loading and radiative forcing.

  5. A Circulation Index for the Himalayan Mountain Arc: Reconciling Conflicting Signals of Climate Change Along the Third Pole"

    NASA Astrophysics Data System (ADS)

    Fowler, H. J.; Forsythe, N. D.; Blenkinsop, S.

    2014-12-01

    Rivers of high mountain Asia are of tremendous importance for livelihoods and well-being of hundreds of millions of people [1]. Independent of climate change the population of the Indus basin will experience water scarcity due to demographic pressures [2]. Recent geophysical research focusing on the Karakoram has revealed patterns of change in both climate [3,4] and cryosphere [5,6] which diverge from the trajectories expected in a globally warming climate. Additional studies have underlined the influence of large-scale atmospheric circulation on glacier mass balance status [7,8]. This study identifies and quantifies a regional feature of atmospheric circulation, the latitudinal position of the westerly jet "immediately upstream" of the Karakoram, which has substantial influence of surface air temperature variability across the Himalayan Mountain Arc and adjacent Indo-Gangetic plains. Characteristics of this feature, and its correlation to local air temperatures, are compared amongst an ensemble of meteorological reanalyses: ERA-40, ERA-Interim, NCEP CFSR, NASA MERRA and JRA-55. Correlations between the westerly jet position and local observations indicate a strong causal mechanism of short term near surface air temperature variability. Furthermore, the Karakoram and NW UIB respond differently during the Summer season to this circulation mode than both the plains of the lower Indus as well as the Central and Eastern Himalaya. This differentiated response provides a plausible explanation for differences in summer temperature trends along the Himalayan arc and by substantiating differences in melt season energy inputs provides a clear climatic mechanism to explain the "Karakoram anomaly." [1] DOI:10.1126/science.330.6004.585-a [2] DOI:10.5194/hess-14-1669-2010 [3] DOI:10.1175/JCLI3860.1 [4] DOI:10.3354/cr00957 [5] DOI:10.1038/ngeo1450 [6] DOI:10.1038/nature11324 [7] DOI:10.1038/nclimate1580 [8] DOI:10.1038/nclimate2055

  6. Acoustic streaming and Sun's meridional circulation

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel

    2016-09-01

    A vast number of physical processes involving oscillations of a bounded viscous fluid are relevantly influenced by acoustic streaming. When this happens a steady circulation of fluid develops in a thin boundary adjacent to the interface. Some examples are refracted sound waves, a fluid inside a spherical cavity undergoing torsional oscillations or a pulsating liquid droplet. Steady streaming around circular interfaces consists of a hemispherically symmetric recirculation of fluid from the equatorial plane to the polar axes closely resembling the meridional circulation pattern observed in the Sun's convection zone that determines the solar cycle. In this paper, it is argued that the acoustic pulsations exhibited by the Sun would lead to acoustic streaming in the boundary of the convection zone. A simple estimation using a typical dominant frequency of 3 mHz and the observed surface oscillation amplitude yields a steady streaming velocity us ∼ 10 m s‑1, which is on the order of the meridional circulation velocity observed in the Sun's convection zone.

  7. Acoustic streaming and Sun's meridional circulation

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel

    2016-09-01

    A vast number of physical processes involving oscillations of a bounded viscous fluid are relevantly influenced by acoustic streaming. When this happens a steady circulation of fluid develops in a thin boundary adjacent to the interface. Some examples are refracted sound waves, a fluid inside a spherical cavity undergoing torsional oscillations or a pulsating liquid droplet. Steady streaming around circular interfaces consists of a hemispherically symmetric recirculation of fluid from the equatorial plane to the polar axes closely resembling the meridional circulation pattern observed in the Sun's convection zone that determines the solar cycle. In this paper, it is argued that the acoustic pulsations exhibited by the Sun would lead to acoustic streaming in the boundary of the convection zone. A simple estimation using a typical dominant frequency of 3 mHz and the observed surface oscillation amplitude yields a steady streaming velocity us ˜ 10 m s‑1, which is on the order of the meridional circulation velocity observed in the Sun's convection zone.

  8. Acoustic streaming and Sun's meridional circulation

    NASA Astrophysics Data System (ADS)

    Valverde, Jose Manuel

    2016-09-01

    A vast number of physical processes involving oscillations of a bounded viscous fluid are relevantly influenced by acoustic streaming. When this happens a steady circulation of fluid develops in a thin boundary adjacent to the interface. Some examples are refracted sound waves, a fluid inside a spherical cavity undergoing torsional oscillations or a pulsating liquid droplet. Steady streaming around circular interfaces consists of a hemispherically symmetric recirculation of fluid from the equatorial plane to the polar axes closely resembling the meridional circulation pattern observed in the Sun's convection zone that determines the solar cycle. In this paper, it is argued that the acoustic pulsations exhibited by the Sun would lead to acoustic streaming in the boundary of the convection zone. A simple estimation using a typical dominant frequency of 3 mHz and the observed surface oscillation amplitude yields a steady streaming velocity us ˜ 10 m s-1, which is on the order of the meridional circulation velocity observed in the Sun's convection zone.

  9. Monsoon-extratropical circulation interactions in Himalayan extreme rainfall

    NASA Astrophysics Data System (ADS)

    Vellore, Ramesh K.; Kaplan, Michael L.; Krishnan, R.; Lewis, John M.; Sabade, Sudhir; Deshpande, Nayana; Singh, Bhupendra B.; Madhura, R. K.; Rama Rao, M. V. S.

    2016-06-01

    Extreme precipitation and flood episodes in the Himalayas are oftentimes traced to synoptic situations involving connections between equatorward advancing upper level extratropical circulations and moisture-laden tropical monsoon circulation. While previous studies have documented precipitation characteristics in the Himalayan region during severe storm cases, a comprehensive understanding of circulation dynamics of extreme precipitation mechanisms is still warranted. In this study, a detailed analysis is performed using rainfall observations and reanalysis circulation products to understand the evolution of monsoon-extratropical circulation features and their interactions based on 34 extreme precipitation events which occurred in the Western Himalayas (WEH) during the period 1979-2013. Our results provide evidence for a common large-scale circulation pattern connecting the extratropics and the South Asian monsoon region, which is favorable for extreme precipitation occurrences in the WEH region. This background upper level large-scale circulation pattern consists of a deep southward penetrating midlatitude westerly trough, a blocking high over western Eurasia and an intensifying Tibetan anticyclone. It is further seen from our analysis that the key elements of monsoon-midlatitude interactions, responsible for extreme precipitation events over the WEH region, are: (1) midlatitude Rossby wave breaking, (2) west-northwest propagation of monsoon low-pressure system from the Bay of Bengal across the Indian subcontinent, (3) eddy shedding of the Tibetan anticyclone, (4) ageostrophic motions and transverse circulation across the Himalayas, and (5) strong moist convection over the Himalayan foothills. Furthermore, high-resolution numerical simulations indicate that diabatic heating and mesoscale ageostrophic effects can additionally amplify the convective motions and precipitation in the WEH region.

  10. Virtual extracorporeal circulation process.

    PubMed

    Boschetti, F; Montevecchi, F M; Fumero, R

    1997-06-01

    Virtual instruments for an extracorporeal circulation (ECC) process were developed to simulate the reactions of a patient to different artificial perfusion conditions. The computer simulation of the patient takes into account the hydraulic, volume, thermal and biochemical phenomena and their interaction with the devices involved in ECC (cannulae dimensions, oxygenator and filter types, pulsatile or continuous pump and thermal exchangers). On the basis of the patient's initialisation data (height, weight, Ht) and perfusion variables (pump flow rate, water temperature, gas flow rate and composition) imposed by the operator, the virtual ECC monitors simulated arterial and venous pressure tracings in real time, along with arterial and venous flow rate tracings, urine production tracing and temperature levels. Oxyhemoglobin arterial and venous blood saturation together with other related variables (pO2, pCO2, pH, HCO3 are also monitored. A drug model which allows the simulation of the effect of vasodilator and diuretic drugs is also implemented. Alarms are provided in order to check which variables (pressure, saturation, pH, urine flow) are out of the expected ranges during the ECC simulation. Consequently the possibility of modifying the control parameters of the virtual devices of the ECC in run-time mode offers an interaction mode between the operator and the virtual environment. PMID:9259211

  11. Effect of two types of helium circulators on the performance of a subsonic nuclear powered airplane

    NASA Technical Reports Server (NTRS)

    Strack, W. C.

    1971-01-01

    Two types of helium circulators are analytically compared on the bases of their influence on airplane payload and on propulsion system variables. One type of circulator is driven by the turbofan engines with power takeoff shafting while the other, a turbocirculator, is powered by a turbine placed in the helium loop between the nuclear reactor and the helium-to-air heat exchangers inside the engines. Typical results show that the turbocirculator yields more payload for circulator efficiencies greater than 0.82. Optimum engine and heat exchanger temperatures and pressures are significantly lower in the turbocirculator case compared to the engine-driven circulator scheme.

  12. Influence of Human Activity Patterns, particle composition, and residential air exchange rates on modeled distributions of PM 2.5 exposure compared with central-site monitoring data

    EPA Science Inventory

    Central-site monitors do not account for factors such as outdoor-to-indoor transport and human activity patterns that influence personal exposures to ambient fine-particulate matter (PM2.5). We describe and compare different ambient PM2.5 exposure estimation...

  13. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  14. Recent accelerating mass loss of southeast Tibetan glaciers and the relationship with changes in macroscale atmospheric circulations

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Guo, Xiaofeng; Yao, Tandong; Zhu, Meilin; Wang, Yongjie

    2016-08-01

    The mass balance history (1980-2010) of a monsoon-dominated glacier in the southeast Tibetan Plateau is reconstructed using an energy balance model and later interpreted with regard to macroscale atmospheric variables. The results show that this glacier is characterized by significant interannual mass fluctuations over the past three decades, with a remarkably high mass loss during the recent period of 2003-2010. Analysis of the relationships between glacier mass balance and climatic variables shows that interannual temperature variability in the monsoonal season (June-September) is a primary driver of its mass balance fluctuations, but monsoonal precipitation tends to play an accentuated role for driving the observed glacier mass changes due to their covariation (concurrence of warm/dry and cold/wet climates) in the monsoon-influenced southeast Tibetan Plateau. Analysis of the atmospheric circulation pattern reveals that the predominance of anticyclonic/cyclonic circulations prevailing in the southeastern/northern Tibetan Plateau during 2003-2010 contributes to increased air temperature and decreased precipitation in the southeast Tibetan Plateau. Regionally contrasting atmospheric circulations explain the distinct mass changes between in the monsoon-influenced southeast Tibetan Plateau and in the north Tibetan Plateau/Tien Shan Mountains during 2003-2010. The macroscale climate change seems to be linked with the Europe-Asia teleconnection.

  15. Why was Atmospheric Circulation Decoupled from Tropical Pacific SSTs in 2014/15 winter?

    NASA Astrophysics Data System (ADS)

    Peng, P.

    2015-12-01

    In late 2014 and early 2015, although Niño3.4 index exceeded the threshold for a weak-moderate El Niño, a canonical atmospheric response to ENSO event was not observed in the central and eastern equatorial Pacific. In an effort to understand why it was so, this study decomposed the DJF mean sea surface temperature (SST), precipitation rate and 200hPa stream function anomalies observed in the 2014/15 winter into the patterns related to the principal components of the DJF SST variability. It is found that the anomalies of these variables were mainly determined by the patterns related to two SST modes, one is the North Pacific Mode (NPM), and the other the El Niño and South Oscillation (ENSO) mode. The NPM was the dominant factor and was responsible for the apparent uncoupled air-sea relationship in the central equatorial Pacific and the east-west structure of the circulation anomalies over North America. The ENSO mode was important for SSTs in the central and eastern equatorial Pacific and for the circulation in the central equatorial Pacific. Further, ENSO signal likely evolved from the NPM pattern in the 2013/14 winter, however, its full development was impeded by the unusual persistence of the strong NPM throughout the year. The analysis for DJF 2014/15 winter indicates that the SST anomalies in Niño3.4 alone were not adequate for capturing the coupling of ocean and atmosphere anomalies in the tropical Pacific, due to the fact that it can't distinguish if the SST anomaly in the Niño3.4 region is associated with the ENSO mode or NPM, or both.

  16. Assessment of the Impact of The East Asian Summer Monsoon on the Air Quality Over China

    NASA Astrophysics Data System (ADS)

    Hao, Nan; Ding, Aijun; Safieddine, Sarah; Valks, Pieter; Clerbaux, Cathy; Trautmann, Thomas

    2016-04-01

    Air pollution is one of the most important environmental problems in developing Asian countries like China. In this region, studies showed that the East Asian monsoon plays a significant role in characterizing the temporal variation and spatial patterns of air pollution, since monsoon is a major atmospheric system affecting air mass transport, convection, and precipitation. Knowledge gaps still exist in the understanding of Asian monsoon impact on the air quality in China under the background of global climate change. For the first time satellite observations of tropospheric ozone and its precursors will be integrated with the ground-based, aircraft measurements of air pollutants and model simulations to study the impact of the East Asian monsoon on air quality in China. We apply multi-platform satellite observations by the GOME-2, IASI, and MOPITT instruments to analyze tropospheric ozone and CO, precursors of ozone (NO2, HCHO and CHOCHO) and other related trace gases over China. Two years measurements of air pollutants including NO2, HONO, SO2, HCHO and CHOCHO at a regional back-ground site in the western part of the Yangtze River Delta (YRD) in eastern China will be presented. The potential of using the current generation of satellite instruments, ground-based instruments and aircraft to monitor air quality changes caused by the East Asian monsoon circulation will be presented. Preliminary comparison results between satellite measurement and limited but valuable ground-based and aircraft measurements will also be showed.

  17. A case study of the Borneo Vortex genesis and its interactions with the global circulation

    NASA Astrophysics Data System (ADS)

    Ooi, See Hai; Samah, Azizan Abu; Braesicke, Peter

    2011-11-01

    During the East Asian winter or the northeast monsoon (November-March), cold surges associated with cold air outbreaks from the Siberian high propagate equatorward and interact with the near-equatorial trough in the southern South China Sea. Usually, in the later phase of the monsoon, the so-called Borneo vortex develops over the sea and is the main driver for the formation of deep convection and heavy rainfall in East Malaysia. We present a case study of a cold-surge-induced event during January 2010. We diagnose a substantial export of potential energy from the Borneo vortex strengthening the subtropical jet. At 200 hPa, the velocity potential maximum related to the established Hadley circulation is shifted eastward from 140°E toward the dateline from presurge to postsurge periods. This modifies the general circulation patterns in the Southern Hemisphere with possible consequences for trace gas distributions. In addition, we explore implications for vertical transport by deep convection occurring in association with the Borneo vortex by diagnosing potential vorticity changes in the vicinity of the vortex.

  18. Forced air heater

    SciTech Connect

    Livezey, D.J.

    1980-09-23

    An air heating chamber is supported to project into a stove through an opening provided in the rear wall of the stove by a mounting plate mounted to the exterior of the stove rear wall. The mounting plate which forms the exterior end wall of the heating chamber, includes laterally spaced heating chamber inlet and outlet openings. A blower is detachably mounted to the exterior of the mounting plate in registration with the heating chamber inlet opening to deliver cool forced air into the heating chamber. After circulating therethrough, the air exits the heating chamber through the outlet opening and flows into a hot air manifold, which is also detachably mounted to the exterior of the mounting plate. The manifold includes an upwardly extending inlet chamber with a hot air inlet at its lower end aligned with the heating chamber outlet opening. A horizontal outlet chamber is attached to the top end of the inlet chamber to extend laterally along the back of the stove. Hot air outlets are provided at each end of the manifold outlet chamber to discharge the heated air horizontally over the top and towards the front of the stove.

  19. Boundary layer roll circulations during FIRE

    NASA Technical Reports Server (NTRS)

    Shirer, Hampton N.; Haack, Tracy

    1990-01-01

    The probable mechanism underlying the development of boundary layer roll circulations are studied using wind and temperature profiles measured by the National Center for Atmospheric Research (NCAR) Electra during the stratocumulus phase of the First ISCCP Regional Experiment (FIRE). The expected, or preferred, roll orientations, horizontal wavelengths, and propagation periods are determined by finding the minimum values of the dynamic and thermodynamic forcing parameters, which here are the eddy Reynolds number (Re) and moist Rayleigh number (Ra sub m). These minimum values depend on the height z sub T of the capping temperature inversion and on the values of the Fourier coefficients of the background height-dependent vector wind profile. As input to our nonlinear spectral model, descent and ascent runs by the Electra provide for initial estimates of the inversion height and the wind profiles. In the first phase of the investigation presented here, a mechanism is said to be a probable contributor to the development of roll circulations within the stratocumulus-topped boundary layer if the modeled roll orientation and wavelengths agree with their observed values. Preliminary results using the 14-coefficient model of Haack-Hirschberg (1988) are discussed for the 7 July 1987 Electra Mission 188-A (Flight 5). This mission was flown across a sharp cloud boundary that was within a LANDSAT/SPOT scene. The stratocumulus deck was relatively solid in the eastern part of the scene, while there was a rapid decrease in cloud cover to scattered cumulus clouds aligned in streets to the west. These cloud streets were oriented nearly parallel to the mean wind direction in the layer, which was approximately 340 degrees. The hypothesis that roll circulations occurred in both the relatively clear and the cloudy regions is investigated using as model input a descent profile obtained in the relatively clear air and an ascent profile obtained in the cloudy air. Initial results for the

  20. Air-cleaning apparatus

    SciTech Connect

    Howard, A.G.

    1981-08-18

    An air-cleaning, heat-exchange apparatus includes a main housing portion connected by means of an air inlet fan to the kitchen exhaust stack of a restaurant. The apparatus includes a plurality of heat exchangers through which a heat-absorptive fluid is circulated, simultaneously, by means of a suitable fluid pump. These heat exchangers absorb heat from the hot exhaust gas, out of the exhaust stack of the restaurant, which flows over and through these heat exchangers and transfers this heat to the circulating fluid which communicates with remote heat exchangers. These remote heat exchangers further transfer this heat to a stream of air, such as that from a cold-air return duct for supplementing the conventional heating system of the restaurant. Due to the fact that such hot exhaust gas is heavily grease laden , grease will be deposited on virtually all internal surfaces of the apparatus which this exhaust gas contacts. Consequently, means are provided for spraying these contacted internal surfaces , as well as the hot exhaust gas itself, with a detergent solution in which the grease is soluble, thereby removing grease buildup from these internal surfaces.

  1. LLNL Ocean General Circulation Model

    2005-12-29

    The LLNL OGCM is a numerical ocean modeling tool for use in studying ocean circulation over a wide range of space and time scales, with primary applications to climate change and carbon cycle science.

  2. Circulation weather types and their influence on precipitation in Serbia

    NASA Astrophysics Data System (ADS)

    Putniković, Suzana; Tošić, Ivana; Đurđević, Vladimir

    2016-10-01

    An objective classification scheme of atmospheric circulation, in which daily circulation is determined by the strength, direction, and vorticity of geostrophic flow, has been applied to the atmosphere over Serbia for the time period 1961-2010. The results for the sea level and isobaric level of 500 hPa for winter and summer are presented. The 26 circulation types (eight pure direction, 16 hybrid, cyclonic, and anticyclonic types) are determined and described. Each of the circulation types has a distinct underlying synoptic pattern that produces the expected type and direction of flow over the study area. The relative frequencies of the circulation types, and the relationship between the precipitation and circulation types at three stations on a seasonal time scale are analyzed. The anticyclonic weather type dominates in winter (18.93 %) and summer (18.70 %), followed by the northeasterly type (16.65 %) in summer, and the cyclonic type (12.83 %) in winter. The cyclonic types (C and hybrid) have a higher than average probability of rain at all stations. Conversely, the anticyclonic types are associated with a lower than average probability and intensity of rainfall.

  3. Modelling the Seasonal Overturning Circulation in the Red Sea

    NASA Astrophysics Data System (ADS)

    Yao, Fengchao; Hoteit, Ibrahim; Pratt, Larry; Bower, Amy; Koehl, Armin; Gopalakrishnan, Ganesh

    2015-04-01

    The overturning circulation in the Red Sea exhibits a distinct seasonally reversing pattern and is studied using 50-year, high-resolution MIT general circulation model simulations. The seasonal water exchange in the Strait of Bab el Mandeb is successfully simulated, and the structures of the intruding subsurface Gulf of Aden intermediate water are in good agreement with summer observations in 2011. The model results suggest that the summer overturning circulation is driven by the combined effect of the shoaling of the thermocline in the Gulf of Aden resulting from remote winds in the Arabian Sea and an upward surface slope from the Red Sea to the Gulf of Aden set up by local surface winds in the Red Sea. For the winter overturning circulation, the climatological model mean results suggest that the surface inflow intensifies in a western boundary current in the southern Red Sea that switches to an eastern boundary current north of 24°N. The overturning is accomplished through a cyclonic recirculation and a cross-basin overturning circulation in the northern Red Sea, with major sinking occurring along a narrow band of width about 20 km along the eastern boundary and weaker upwelling along the western boundary. The northward pressure gradient force, strong vertical mixing, and horizontal mixing near the boundary are the essential dynamical components in the model's winter overturning circulation.

  4. Effect of surface gravity waves on atmospheric circulation

    SciTech Connect

    Janssen, P.A.E.M. |

    1994-12-31

    During the last decade there has been considerable interest in the problem of the interaction of wind and waves with emphasis on the sea state dependence of the momentum transfer across the air-sea interface. Simulations with the WAM model show that, depending on the sea state, the drag coefficient may vary by a factor of two. Therefore, one may wonder whether two-way interaction has impact on e.g. the evolution of a depression and the atmospheric circulation. In order to study systematic effects on the atmospheric circulation, climate runs have to be performed. Performing Monte Carlo Forecasting with the coupled WAM-ECMWF model for the winter season 1990, it is concluded that surface gravity waves have a significant impact on the atmospheric circulation.

  5. Air. Ag Ed Environmental Education Series.

    ERIC Educational Resources Information Center

    Tulloch, Rodney W.

    The document is a student resource unit to be used in teaching high school vocational agriculture students about air. The following natural processes are described: carbon dioxide cycle, nitrogen cycle, gravity and atmosphere, energy of the sun, greenhouse effect, atmospheric circulation, and precipitation. Sources of air pollution are discussed.…

  6. Interannual variability of South American monsoon circulation

    NASA Astrophysics Data System (ADS)

    Alonso Gan, Manoel; Rafaele Araújo Lima, Jeane

    2016-04-01

    The South America Monsoon System (SAMS) is responsible for influencing the atmospheric circulation and precipitation over most of tropical South America (SA) during the summer season. Studies for aiming to understand the temporal variability of this system have great value to the scientific community, because the processes that control the monsoon climate are not totally clear. Thus, the main objective of this research is to investigate the possible large-scale climatic factors and the remote interaction mechanisms, which may be associated with summer season interannual variability focusing on identifying the main differences between dry and wet extremes rainy season in the South-eastern Amazon Basin (SAB), Central-West (WC) and Southeast (SE) of Brazil, which are areas influenced by the summer monsoon regime. For such analyzes, Pearson correlations, quantile method and composite analysis were used during the period from 1979 to 2014. The correlation between precipitation anomaly in SAB and the sea surface temperature anomaly (SSTA) and wind at 850hPa and 300hPa indicate El Niño-Southern Oscillation (ENSO) influence. Precipitation anomalies in WC did not show significant correlation with SSTA. However, a pattern similar to ENSO Modoki type was observed in the composite analysis. At 850 hPa, the presence of an anomalous cyclonic (anticyclonic) circulation was observed over the central region of SA during wet (dry) summers seasons. Over SE region of Brazil, a dipole SSTA pattern over the South Atlantic was identified, as well the presence of anomalous circulations with an equivalent barotropic structure over these SSTA areas. This pattern