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Sample records for winter cold front

  1. Cold Fronts in Cold Dark Matter Clusters

    NASA Astrophysics Data System (ADS)

    Nagai, Daisuke; Kravtsov, Andrey V.

    2003-04-01

    Recently, high-resolution Chandra observations revealed the existence of very sharp features in the X-ray surface brightness and temperature maps of several clusters. These features, called cold fronts, are characterized by an increase in surface brightness by a factor >~2 over 10-50 kpc accompanied by a drop in temperature of a similar magnitude. The existence of such sharp gradients can be used to put interesting constraints on the physics of the intracluster medium (ICM) if their mechanism and longevity are well understood. Here, we present results of a search for cold fronts in high-resolution simulations of galaxy clusters in cold dark matter models. We show that sharp gradients with properties similar to those of observed cold fronts naturally arise in cluster mergers when the shocks heat gas surrounding the merging subcluster, while its dense core remains relatively cold. The compression induced by supersonic motions and shock heating during the merger enhance the amplitude of gas density and temperature gradients across the front. Our results indicate that cold fronts are nonequilibrium transient phenomena and can be observed for a period of less than a billion years. We show that the velocity and density fields of gas surrounding the cold front can be very irregular, which would complicate analyses aiming to put constraints on the physical conditions of the ICM in the vicinity of the front.

  2. HF Doppler and VHF radar observations of upper atmospheric disturbances caused by weak cold front during winter time

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Lee, C. C.; Gao, M.; Johnson, D. L.; Yang, F. W.

    1990-01-01

    The simultaneous use of the Taiwan VHF radar and the HF Doppler sounder for remote measurement of three-dimensional winds, gravity waves, and density perturbations at mesospheric and thermospheric heights is demonstrated. A special event of atmospheric disturbances caused by propagating gravity waves excited by weak convective motions in winter time were investigated. The three-dimensional wind velocities at different heights were determined, and the frequency, horizontal wavelength, vertical wavelength, and phase velocity of the gravity waves were measured. The subtropical, low-latitude site makes the VHF radar and HF Doppler array systems unique, and the observations especially valuable for space projects dealing with low-latitude atmosphere.

  3. Nitrogen and phosphorus transport between Fourleague Bay, LA, and the Gulf of Mexico: The role of winter cold fronts and Atchafalaya River discharge

    USGS Publications Warehouse

    Perez, B.C.; Day, J.W., Jr.; Justic, D.; Twilley, R.R.

    2003-01-01

    Nutrient fluxes were measured between Fourleague Bay, a shallow Louisiana estuary, and the Gulf of Mexico every 3 h between February 1 and April 30, 1994 to determine how high velocity winds associated with cold fronts and peak Atchafalaya River discharge influenced transport. Net water fluxes were ebb-dominated throughout the study because of wind forcing and high volumes of water entering the northern Bay from the Atchafalaya River. Flushing time of the Bay averaged <8 days; however, more rapid flushing occurred in response to northerly winds with approximately 56% of the volume of the Bay exported to the Gulf in 1 day during the strongest flushing event. Higher nitrate + nitrite (NO2+ NO3), total nitrogen (TN), and total phosphorus (TP) concentrations were indicative of Atchafalaya River input and fluxes were greater when influenced by high velocity northerly winds associated with frontal passage. Net exports of NO2 + NO3, TN, and TP were 43.5, 98.5, and 13.6 g s-1, respectively, for the 89-day study. An average of 10.6 g s-1 of ammonium (NH4) was exported to the Gulf over the study; however, concentrations were lower when associated with riverine influence and wind-driven exports suggesting the importance of biological processes. Phosphate (PO4) fluxes were nearly balanced over the study with fairly stable concentrations indicating a well-buffered system. The results indicate that the high energy subsidy provided by natural pulsing events such as atmospheric cold fronts and seasonal river discharge are efficient mechanisms of nutrient delivery to adjacent wetlands and nearshore coastal ecosystems and are important in maintaining coastal sustainability. ?? 2003 Elsevier Ltd. All rights reserved.

  4. Shocks and cold fronts in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Markevitch, Maxim; Vikhlinin, Alexey

    2007-05-01

    The currently operating X-ray imaging observatories provide us with an exquisitely detailed view of the Megaparsec-scale plasma atmospheres in nearby galaxy clusters. At z<0.05, the Chandra's 1 angular resolution corresponds to linear resolution of less than a kiloparsec, which is smaller than some interesting linear scales in the intracluster plasma. This enables us to study the previously unseen hydrodynamic phenomena in clusters: classic bow shocks driven by the infalling subclusters, and the unanticipated “cold fronts,” or sharp contact discontinuities between regions of gas with different entropies. The ubiquitous cold fronts are found in mergers as well as around the central density peaks in “relaxed” clusters. They are caused by motion of cool, dense gas clouds in the ambient higher-entropy gas. These clouds are either remnants of the infalling subclusters, or the displaced gas from the cluster's own cool cores. Both shock fronts and cold fronts provide novel tools to study the intracluster plasma on microscopic and cluster-wide scales, where the dark matter gravity, thermal pressure, magnetic fields, and ultrarelativistic particles are at play. In particular, these discontinuities provide the only way to measure the gas bulk velocities in the plane of the sky. The observed temperature jumps at cold fronts require that thermal conduction across the fronts is strongly suppressed. Furthermore, the width of the density jump in the best-studied cold front is smaller than the Coulomb mean free path for the plasma particles. These findings show that transport processes in the intracluster plasma can easily be suppressed. Cold fronts also appear less prone to hydrodynamic instabilities than expected, hinting at the formation of a parallel magnetic field layer via magnetic draping. This may make it difficult to mix different gas phases during a merger. A sharp electron temperature jump across the best-studied shock front has shown that the electron proton

  5. Interaction of a cold front with a sea-breeze front Numerical simulations

    NASA Astrophysics Data System (ADS)

    Rhodin, A.

    1995-08-01

    This paper presents simulations of a front which passed the coast between the North Sea and northern Germany and thereby experienced some modifications of its mesoscale characteristics. The event was observed during the field experiment FRONTEX'89. The two-dimensional non-hydrostatic simulations presented in this paper resemble some of the observed characteristics and yield a detailed description of the evolution of the surface front. Over the sea several narrow frontal rain bands develop in the boundary layer which becomes unstable due to the increasing sea surface temperature near the coast. The rain bands move forward relative to the front due to the cross frontal circulation which is enhanced by the release of latent heat in the ascending warm air and by the cooling of the cold air below by evaporating precipitation. Over the heated land surface a sea-breeze front develops ahead of the synoptic-scale cold front. The strong frontal gradients of the sea-breeze front mask the broader frontal zone of the cold front at the ground. The sea-breeze front triggers deep convection ahead of the cold front in the afternoon and takes over all characteristics of the synoptic-scale front in the evening. The simulations show the mechanisms that caused the observed evolution and modification of the synoptic-scale cold front. They emphasize the strong influence of the surface heat fluxes on the characteristics of fronts on the mesoscale. The most important feature of the numerical model, necessary for the proper representation of the frontal characteristics on the mesoscale, is its high resolution. The simulations are restricted by the difficulties of finding an initial state and appropriate boundary conditions so that the results fit the observations for a long time period and that spin-up problems are avoided.

  6. Does cold winter weather produce depressive symptoms?

    NASA Astrophysics Data System (ADS)

    Garvey, Michael J.; Goodes, Mike; Furlong, Candy; Tollefson, Gary D.

    1988-06-01

    To examine whether harsh winter weather is associated with depressive symptoms, 45 healthy subjects from Minnesota were compared to 42 subjects from California near the end of the winter season. No differences in the prevalence of depressive symptoms were found between the two groups.

  7. Cold Fronts in Clusters of Galaxies: Observations and Modeling

    NASA Technical Reports Server (NTRS)

    Markevitch, Maxim

    2012-01-01

    Mergers of galaxy clusters -- some of the most energetic events in the Universe -- produce disturbances in hot intracluster medium, such as shocks and cold fronts, that can be used as tools to study the physics of galaxy clusters. Cold fronts may constrain viscosity and the structure and strength of the cluster magnetic fields. Combined with radio data, these observations also shed light on the production of ultrarelativistic particles that are known to coexist with the cluster thermal plasma. This talk will summarize the current X-ray observations of cluster mergers, as well as some recent radio data and high resolution hydrodynamic simulations.

  8. Intensification of the subpolar front in the Sea of Japan during winter cyclones

    NASA Astrophysics Data System (ADS)

    Zhao, Ning; Iwasaki, Shinsuke; Isobe, Atsuhiko; Lien, Ren-Chieh; Wang, Bin

    2016-04-01

    The response of the subpolar front in the Sea of Japan (also known as the East Sea) to winter cyclones is investigated based on quantitative analyses of gridded and satellite data sets. Cyclone passages affecting the sea are detected using time series of spatially averaged surface turbulent heat fluxes. As the cyclones develop, there are strong cold-air outbreaks that produce twice the normal heat loss over the sea. After removal of sea surface temperature (SST) seasonal trends, we found that cyclone passage (hence, cooling) mainly occurred over 3 days, with maximum SST reduction of -0.4°C. The greatest reduction was found along the subpolar front, where frontal sharpness (i.e., SST gradient) increased by 0.1°C (100 km)-1. Results of a mixed-layer model were consistent with both temperature and frontal sharpness, and localized surface cooling along the subpolar front resulted from both horizontal heat advection and turbulent heat fluxes at the sea surface. Further analyses show that this localized cooling from horizontal heat advection is caused by the cross-frontal Ekman flow (vertically averaged over the mixed layer) and strong northwesterly winds associated with the cold-air outbreak during cyclone passage.

  9. Cold fronts: probes of plasma astrophysics in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Zuhone, John A.; Roediger, E.

    2016-06-01

    > The most massive baryonic component of galaxy clusters is the `intracluster medium' (ICM), a diffuse, hot, weakly magnetized plasma that is most easily observed in the X-ray band. Despite being observed for decades, the macroscopic transport properties of the ICM are still not well constrained. A path to determine macroscopic ICM properties opened up with the discovery of `cold fronts'. These were observed as sharp discontinuities in surface brightness and temperature in the ICM, with the property that the denser side of the discontinuity is the colder one. The high spatial resolution of the Chandra X-ray Observatory revealed two puzzles about cold fronts. First, they should be subject to Kelvin-Helmholtz instabilities, yet in many cases they appear relatively smooth and undisturbed. Second, the width of the interface between the two gas phases is typically narrower than the mean free path of the particles in the plasma, indicating negligible thermal conduction. It was thus realized that these special characteristics of cold fronts may be used to probe the properties of the cluster plasma. In this review, we will discuss the recent simulations of cold fronts in galaxy clusters, focusing on those which have attempted to use these features to constrain ICM physics. In particular, we will examine the effects of magnetic fields, viscosity, and thermal conductivity on the stability properties and long-term evolution of cold fronts. We conclude with a discussion on what important questions remain unanswered, and the future role of simulations and the next generation of X-ray observatories.

  10. Cold Fronts Research Programme: Progress, Future Plans, and Research Directions.

    NASA Astrophysics Data System (ADS)

    Ryan, B. F.; Wilson, K. J.; Garratt, J. R.; Smith, R. K.

    1985-09-01

    Following the analysis of data collected during Phases land II of the Cold Fronts Research Programme (CFRP) a conceptual model for the Australian summertime "cool change" has been proposed. The model provides a focus and a framework for the design of Phase III.The model is based on data gathered from a mesoscale network centered on Mount Gambier, South Australia, and includes the coastal waters to the west and relatively flat terrain to the east. The first objective of Phase III is to generalize the model so that it is applicable to the ocean waters to the far west of Mount Gambier and to the more rugged terrain farther to the east in the vicinity of Melbourne, Victoria. The remaining objectives concentrate on resolving unsatisfactory aspects of the model such as the evolution of convective lines and the relationship between the surface cold front and the upper-tropospheric cold pool and its associated jet stream.The integrated nature of the Cold Fronts Research Programme has meant that it has stimulated a wide range of research activities that extend beyond the field observations. The associated investigations include climatological, theoretical, and numerical modeling studies.

  11. Fast Simulations of Gas Sloshing and Cold Front Formation

    NASA Technical Reports Server (NTRS)

    Roediger, E.; ZuHone, J. A.

    2012-01-01

    We present a simplified and fast method for simulating minor mergers between galaxy clusters. Instead of following the evolution of the dark matter halos directly by the N-body method, we employ a rigid potential approximation for both clusters. The simulations are run in the rest frame of the more massive cluster and account for the resulting inertial accelerations in an optimised way. We test the reliability of this method for studies of minor merger induced gas sloshing by performing a one-to-one comparison between our simulations and hydro+N-body ones. We find that the rigid potential approximation reproduces the sloshing-related features well except for two artifacts: the temperature just outside the cold fronts is slightly over-predicted, and the outward motion of the cold fronts is delayed by typically 200 Myr. We discuss reasons for both artifacts.

  12. Fast Simulations of Gas Sloshing and Cold Front Formation

    NASA Technical Reports Server (NTRS)

    Roediger, E.; ZuHone, J. A.

    2011-01-01

    We present a simplified and fast method for simulating minor mergers between galaxy clusters. Instead of following the evolution of the dark matter halos directly by the N-body method, we employ a rigid potential approximation for both clusters. The simulations are run in the rest frame of the more massive cluster and account for the resulting inertial accelerations in an optimised way. We test the reliability of this method for studies of minor merger induced gas sloshing by performing a one-to-one comparison between our simulations and hydro+N-body ones. We find that the rigid potential approximation reproduces the sloshing-related features well except for two artefacts: the temperature just outside the cold fronts is slightly over-predicted, and the outward motion of the cold fronts is delayed by typically 200 Myr. We discuss reasons for both artefacts.

  13. Fast simulations of gas sloshing and cold front formation

    NASA Astrophysics Data System (ADS)

    Roediger, E.; Zuhone, J. A.

    2012-01-01

    We present a simplified and fast method for simulating minor mergers between galaxy clusters. Instead of following the evolution of the dark matter haloes directly by the N-body method, we employ a rigid potential approximation for both clusters. The simulations are run in the rest frame of the more massive cluster and account for the resulting inertial accelerations in an optimized way. We test the reliability of this method for studies of minor merger induced gas sloshing by performing a one-to-one comparison between our simulations and hydro+N-body ones. We find that the rigid potential approximation reproduces the sloshing-related features well except for two artefacts: the temperature just outside the cold fronts is slightly overpredicted, and the outward motion of the cold fronts is delayed by typically 200 Myr. We discuss reasons for both artefacts.

  14. Early winter cold spells over the Euro-Mediterranean region

    NASA Astrophysics Data System (ADS)

    Toreti, Andrea; Xoplaki, Elena; Luterbacher, Juerg

    2016-04-01

    In a changing climate context, temperature extremes are expected to heavily impact societies and economies. Projected changes in warm extremes have been extensively investigated, while less efforts are devoted to cold extremes. Despite the projected warming of the climate system, cold extremes could still occur and have an impact on several sectors, such as human health and agriculture. Here, we focus on cold spells that have a potential high impact, i.e. early winter cold spells occurring after a mild-to-warm autumn. Projected changes of these events over the Euro-Mediterranean region are analysed by using the latest Euro-Cordex simulations under the scenarios RCP4.5 and RCP8.5. In terms of spatial extension of cold spells, a significant reduction can be seen only at the end of the 21st century and under the RCP8.5 scenario. As for the changes in intensity in the mid-century, no consistency is found among models over large areas. At the end of the century, the north-eastern part of the domain and northern Africa are projected to be early-cold-spell free under the RCP4.5 scenario, while, almost the entire domain is projected to be early-cold-spell free under the RCP8.5 scenario.

  15. Winter Cold tongue in the South China Sea

    NASA Astrophysics Data System (ADS)

    Thompson, B.; Tkalich, P.; Rizzoli, P. M.

    2014-12-01

    The South China Sea (SCS) surface circulation is mainly forced by seasonally varying monsoon winds and flow through the Luzon Strait. In winter, positive wind curl (due to the northeasterly winds) in the southern half of SCS drives a cyclonic gyre. The strong western boundary current south off Vietnam on the continental slope separates the Sunda Shelf to the west and deep SCS basin to the east. The advection of cold water due to the slope current results in a unique cold tongue in Sea Surface Temperature (SST) from November to February. The inter-annual variability of this cold-tongue is investigated by analyzing the NCEP OISST version-2 dataset. Dynamics of the evolution, growth and decay of the cold tongue during the period 1982-2012 are addressed using the OISST and ERA-interim surface wind datasets. The role of water mass advection in the inter-annual variability of SCS cold-tongue is also investigated through the analysis of lateral heat fluxes estimated from NCEP-Climate Forecast System Re-analysis dataset. The vertically integrated Ekman transport (i.e., the Sverdrup transport) plays a vital role in the formation this cold tongue. The southward Sverdrup transport brings cold water from the northern parts of the SCS. Inter-annual variations in the cold tongue SST during the northeast monsoon (November to February) are strongly linked to the north-south Sverdrup and zonal Ekman transport anomalies. The positive SST anomalies over the cold-tongue region are associated with positive transport anomalies, reflecting the weakening of the southward and westward advection. The formation and termination of this cold tongue has significant correlation with the El Nino phenomenon in the Pacific Ocean.

  16. On a theory of the evolution of surface cold fronts

    NASA Technical Reports Server (NTRS)

    Levy, Gad; Bretherton, Christopher S.

    1987-01-01

    The governing vorticity and divergence equations in the surface layer are derived and the roles of the different terms and feedback mechanisms are investigated in semigeostrophic and nongeostrophic cold-frontal systems. A planetary boundary layer model is used to perform sensitivity tests to determine that in a cold front the ageostrophic feedback mechanism as defined by Orlanski and Ross tends to act as a positive feedback mechanism, enhancing vorticity and convergence growth. Therefore, it cannot explain the phase shift between convergence and vorticity as simulated by Orlanski and Ross. An alternative plausible, though tentative, explanation in terms of a gravity wave is offered. It is shown that when the geostrophic deformation increases, nonlinear terms in the divergence equation may become important and further destabilize the system.

  17. New Perspectives on Intermountain Cyclones and Cold Fronts

    NASA Astrophysics Data System (ADS)

    Steenburgh, W. J.; West, G.; Neuman, C.; Shafer, J.; Jeglum, M.; Bosart, L. F.; Lee, T.

    2011-12-01

    The topography in and around the Intermountain West strongly affects the genesis, migration, and lysis of extratropical cyclones and cold fronts. In this presentation, we summarize new perspectives on Intermountain cyclone and cold-front evolution derived from recent climatological, observational, and modeling studies based on high-density observations and high-resolution reanalyses and numerical simulations. Recent high-resolution reanalyses show that Intermountain cyclone activity is greatest in two distinct regions. The first, which we call the Great Basin cyclone region, extends northeastward from the southern high Sierra to the Great Salt Lake Basin of northwest Utah. The second, which we call the Canyonlands cyclone region, lies over the upper Colorado River Basin of southeast Utah, a lowland region between the mountains and plateaus of central Utah and the Colorado Rockies. Composites of strong Intermountain cyclones generated in cross-Sierra (210-300°) 500-hPa flow show that cyclogenesis is preceeded by the development of the Great Basin Confluence Zone (GBCZ), a regional airstream boundary that extends downstream from the Sierra Nevada. Cyclogenesis occurs along the GBCZ as large-scale ascent develops over the Intermountain West in advance of an approaching upper-level trough. Flow splitting around the high Sierra and the presence of low-level baroclinity along the GBCZ suggest that Intermountain Cyclogenesis might be better conceptualized from a potential vorticity perspective than from traditional quasigeostrophic models of lee cyclogenesis. Surface observations indicate that the frequency of strong cold-frontal passages increases dramatically from the Cascade-Sierra Mountains to northern Utah, suggesting that the Intermountain West is a frequent cold-frontal breeding ground. Two case studies help illustrate the mechanisms contributing to these strong cold-frontal passages. During the 2002 Tax Day Cyclone, strong contraction (i.e., deformation and

  18. On the water thermal response to the passage of cold fronts: initial results for Itumbiara reservoir (Brazil)

    NASA Astrophysics Data System (ADS)

    Alcântara, E. H.; Bonnet, M. P.; Assireu, A. T.; Stech, J. L.; Novo, E. M. L. M.; Lorenzzetti, J. A.

    2010-12-01

    The passage of meteorological systems such as cold fronts or convergence zones over reservoirs can cause significant modifications in several aquatic variables. Cold fronts coming from higher latitudes and reaching the Southeastern Brazilian territory modify the mean wind field and have important impact over physical, chemical and biological processes that act in the hydroelectric reservoirs. The mean period of cold front passages along the Southeastern Brazilian coast is 6 days during the winter and between 11 and 14 days in the summer. Most of these fronts also affect the hinterland of São Paulo, Minas Gerais and Goiás states. The objective of this work is to analyze the influence of cold front passages in the thermal stratification and water quality of the Itumbiara hydroelectric reservoir which is located in Minas Gerais and Goiás. The characterization of cold front passages over the study area was done through the analysis of GOES satellite images. The analyzed data set includes time series of meteorological (wind direction and intensity, short-wave radiation, air temperature, relative humidity, atmospheric pressure) and water temperature in four depths (5, 12, 20 and 40 m). The data set was acquired in the interior of the reservoir by an autonomous anchored buoy system at a sampling rate of 1 h. The stratification was assessed by non-dimensional parameter analysis. The lake number an indicator of the degree of stability and mixing in the reservoir was used in this analysis. We will show that during the cold front all atmospheric parameters respond and this response are transferred immediately to the water surface. The main effect is observed in the water column, when the heat loss in the surface allows the upwelling events caused by convective cooling due to the erosion of thermal stratification.

  19. Effect of cold wave on winter visibility over eastern China

    NASA Astrophysics Data System (ADS)

    Qu, Wenjun; Wang, Jun; Zhang, Xiaoye; Yang, Zhifeng; Gao, Shanhong

    2015-03-01

    Considerable concern has been raised on the severe wintertime haze episodes over eastern China (ECN) where visibility (Vis) decline in winter is identified from 1973 to 2012 (-0.68 km per 10 years or -26% in 40 years). Based upon the analysis of daily Vis and weather records, cold wave (CW) originating from high latitudes is found to increase Vis by 2.7 km on average because of its relatively stronger wind and drier, cleaner air mass compared with the typical, stable midlatitude air over ECN in winter. However, the lessening frequency of CW occurrence and cold air activity in recent years and the accompanied decrease of surface wind speed (-0.15 m/s per 10 years or -18% in the 40 years) may have amplified the effect of increased anthropogenic emissions on Vis and consequently resulted in more substantial Vis decline. A comparison of Vis trends on the "normal wind" days and on all days in winter implies that the emission increase has contributed to about 79% of the declining Vis trend, while the meteorology change contributed 21%. Furthermore, the diurnal cycle of the boundary layer height is found to have weakened or in some cases disappeared in the winters with less CW, which probably contributed to the long-lasting characteristic of the wintertime low Vis events in this region. Hence, the effect of climate change, such as the decrease of CW occurrence, should be accounted as part of the interpretation for the steady decrease of winter Vis over ECN in the past four decades.

  20. Exceptionally cold and mild winters in Europe (1951-2010)

    NASA Astrophysics Data System (ADS)

    Twardosz, Robert; Kossowska-Cezak, Urszula

    2016-07-01

    Extreme thermal conditions appear to occupy an important place among research subjects at a time of climate warming. This study investigates the frequency, duration and spatial extent of thermally anomalous winters in Europe during the 60 years between 1951 and 2010. Exceptionally cold winters (ECWs) and exceptionally mild winters (EMWs) were identified using the statistical criterion of plus/minus two standard deviations from the long-term winter temperature (January-December) recorded at 60 weather stations. It was demonstrated that ECWs have occurred more frequently and covered larger territories than EMWs and that they may occur anywhere in Europe, while EMWs were limited to its southern and western parts. ECWs are characterised by greater absolute temperature anomalies, as anomalies greater than |6.0 °C| account for 35 % of ECWs, but only for 8 % of EMWs. The greatest anomalies are found in the east of the continent. The largest territory affected by an ECW included 24 stations in 1962/1963, while the equivalent among the EMWs included 11 stations in 2006/2007. The study also confirmed an expected trend whereby ECWs diminished in frequency in favour of EMWs in the second half of the 60-year study period.

  1. Habitat suitability index models: greater white-fronted goose (wintering). [Anser albifrons

    SciTech Connect

    Kaminski, R.M.

    1986-07-01

    A review and synthesis of available information were used to develop models for indexing the potential suitability of agricultural and natural wetland habitats for wintering white-fronted geese (Anser albifrons). The model is scaled to produce indices of habitat suitability from 0 (unsuitable habitat) to 1.0 (optimal habitat) primarily for wintering habitat in southwest Louisiana and southwest Texas. Habitat suitability indices are designed for use with Habitat Evaluations Procedures previously developed by the US Fish and Wildlife Service.

  2. Social perceptions versus meteorological observations of snow and winter along the Front Range

    NASA Astrophysics Data System (ADS)

    Milligan, William James, IV

    This research aims to increase understanding of Front Range residents' perceptions of snow, winter and hydrologic events. This study also investigates how an individual's characteristics may shape perceptions of winter weather and climate. A survey was administered to determine if perceptions of previous winters align with observed meteorological data. The survey also investigated how individual characteristics influence perceptions of snow and winter weather. The survey was conducted primarily along the Front Range area of the state of Colorado in the United States of America. This is a highly populated semi-arid region that acts as an interface between the agricultural plains to the east that extend to the Mississippi River and the Rocky Mountains to the west. The climate is continental, and while many people recreate in the snowy areas of the mountains, most live where annual snowfall amounts are low. Precipitation, temperature, and wind speed datasets from selected weather stations were analyzed to determine correct survey responses. Survey analysis revealed that perceptions of previous winters do not necessarily align with observed meteorological data. The mean percentage of correct responses to all survey questions was 36.8%. Further analysis revealed that some individual characteristics (e.g. winter recreation, source of winter weather information) did influence correct responses to survey questions.

  3. Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold

    PubMed Central

    Laist, David W.; Taylor, Cynthia; Reynolds, John E.

    2013-01-01

    To survive cold winter periods most, if not all, Florida manatees rely on warm-water refuges in the southern two-thirds of the Florida peninsula. Most refuges are either warm-water discharges from power plant and natural springs, or passive thermal basins that temporarily trap relatively warm water for a week or more. Strong fidelity to one or more refuges has created four relatively discrete Florida manatee subpopulations. Using statewide winter counts of manatees from 1999 to 2011, we provide the first attempt to quantify the proportion of animals using the three principal refuge types (power plants, springs, and passive thermal basins) statewide and for each subpopulation. Statewide across all years, 48.5% of all manatees were counted at power plant outfalls, 17.5% at natural springs, and 34.9 % at passive thermal basins or sites with no known warm-water features. Atlantic Coast and Southwest Florida subpopulations comprised 82.2% of all manatees counted (45.6% and 36.6%, respectively) with each subpopulation relying principally on power plants (66.6% and 47.4%, respectively). The upper St. Johns River and Northwest Florida subpopulations comprised 17.8% of all manatees counted with almost all animals relying entirely on springs (99.2% and 88.6% of those subpopulations, respectively). A record high count of 5,076 manatees in January 2010 revealed minimum sizes for the four subpopulations of: 230 manatees in the upper St. Johns River; 2,548 on the Atlantic Coast; 645 in Northwest Florida; and 1,774 in Southwest Florida. Based on a comparison of carcass recovery locations for 713 manatees killed by cold stress between 1999 and 2011 and the distribution of known refuges, it appears that springs offer manatees the best protection against cold stress. Long-term survival of Florida manatees will require improved efforts to enhance and protect manatee access to and use of warm-water springs as power plant outfalls are shut down. PMID:23527063

  4. Winter habitat preferences for Florida manatees and vulnerability to cold.

    PubMed

    Laist, David W; Taylor, Cynthia; Reynolds, John E

    2013-01-01

    To survive cold winter periods most, if not all, Florida manatees rely on warm-water refuges in the southern two-thirds of the Florida peninsula. Most refuges are either warm-water discharges from power plant and natural springs, or passive thermal basins that temporarily trap relatively warm water for a week or more. Strong fidelity to one or more refuges has created four relatively discrete Florida manatee subpopulations. Using statewide winter counts of manatees from 1999 to 2011, we provide the first attempt to quantify the proportion of animals using the three principal refuge types (power plants, springs, and passive thermal basins) statewide and for each subpopulation. Statewide across all years, 48.5% of all manatees were counted at power plant outfalls, 17.5% at natural springs, and 34.9 % at passive thermal basins or sites with no known warm-water features. Atlantic Coast and Southwest Florida subpopulations comprised 82.2% of all manatees counted (45.6% and 36.6%, respectively) with each subpopulation relying principally on power plants (66.6% and 47.4%, respectively). The upper St. Johns River and Northwest Florida subpopulations comprised 17.8% of all manatees counted with almost all animals relying entirely on springs (99.2% and 88.6% of those subpopulations, respectively). A record high count of 5,076 manatees in January 2010 revealed minimum sizes for the four subpopulations of: 230 manatees in the upper St. Johns River; 2,548 on the Atlantic Coast; 645 in Northwest Florida; and 1,774 in Southwest Florida. Based on a comparison of carcass recovery locations for 713 manatees killed by cold stress between 1999 and 2011 and the distribution of known refuges, it appears that springs offer manatees the best protection against cold stress. Long-term survival of Florida manatees will require improved efforts to enhance and protect manatee access to and use of warm-water springs as power plant outfalls are shut down. PMID:23527063

  5. Chandra, Cold Fronts, and ICM Physics: The Importance of Magnetic Fields

    NASA Astrophysics Data System (ADS)

    ZuHone, John

    2014-11-01

    One of the most prominent features that the superb spatial resolution of Chandra has revealed in the galaxy cluster plasma is cold fronts: sharp surface brightness and temperature discontinuities formed by the motion of cold, dense gas. Cold fronts should be susceptible to disruption by fluid instabilites and smoothing out by thermal conduction, but many appear to be resilient to these effects, indicating suppression by microphysical processes. I will summarize a series of MHD simulations of sloshing cold fronts in galaxy clusters with anisotropic viscosity and thermal conduction. I will show that the power of cold front studies to provide constraints on the plasma conductivity is potentially strong, whereas the outlook for constraining the plasma viscosity is more uncertain.

  6. THE PROPERTIES OF X-RAY COLD FRONTS IN A STATISTICAL SAMPLE OF SIMULATED GALAXY CLUSTERS

    SciTech Connect

    Hallman, Eric J.; Skillman, Samuel W.; Smith, Britton D.; Burns, Jack O.; Jeltema, Tesla E.; Norman, Michael L.

    2010-12-10

    We examine the incidence of cold fronts in a large sample of galaxy clusters extracted from a (512 h {sup -1} Mpc) hydrodynamic/N-body cosmological simulation with adiabatic gas physics computed with the Enzo adaptive mesh refinement code. This simulation contains a sample of roughly 4000 galaxy clusters with M {>=}10{sup 14} M{sub sun} at z = 0. For each simulated galaxy cluster, we have created mock 0.3-8.0 keV X-ray observations and spectroscopic-like temperature maps. We have searched these maps with a new automated algorithm to identify the presence of cold fronts in projection. Using a threshold of a minimum of 10 cold front pixels in our images, corresponding to a total comoving length L{sub cf}>156 h {sup -1} kpc, we find that roughly 10%-12% of all projections in a mass-limited sample would be classified as cold front clusters. Interestingly, the fraction of clusters with extended cold front features in our synthetic maps of a mass-limited sample trends only weakly with redshift out to z = 1.0. However, when using different selection functions, including a simulated flux limit, the trending with redshift changes significantly. The likelihood of finding cold fronts in the simulated clusters in our sample is a strong function of cluster mass. In clusters with M>7.5 x 10{sup 14} M{sub sun} the cold front fraction is 40%-50%. We also show that the presence of cold fronts is strongly correlated with disturbed morphology as measured by quantitative structure measures. Finally, we find that the incidence of cold fronts in the simulated cluster images is strongly dependent on baryonic physics.

  7. [Safe wintering and economic and ecological benefit of winter rapeseed in dry and cold areas of northern China].

    PubMed

    Liu, Hai-qing; Sun, Wan-cang; Liu, Zi-gang; Wang, Zhi-jiang; Fang, Yuan; Wu, Jun-yan; Li, Xue-cai; Fang, Yan

    2015-10-01

    The purpose of this study was to realize the security of safe wintering of winter rapeseed in dry and cold regions of northern China. Experiments were conducted with 18 winter rapeseed (Brassica campestris) varieties at 57 sites from 2008 to 2013 to statistically analyze the wintering rate variation of different varieties in dry and cold regions of northern China. The results showed that, the wintering rate varied from 70% to 90% during the study period in different regions, which had no significant difference between different years and varieties, and had high stability and remarkable economic benefit. With Tianshui as a starting point of winter rapeseed planting, the wintering-safe regions included all Gansu Province , the south of Lasa and Linzhi of Xizang, the east of Minhe of Qinghai, up to Urumqi and Baicheng, and the south of Aletai, Tacheng, the east of Kashi of Xinjiang, it also included the regions along Yellow River eastward to Ningxia, the south of Linhe of Inner Mongolia, the north of Shaanxi, the vicinage of Qixian in Shanxi, Daming in Hebei, Tianjin, Beijing, the north of Weifang of Shandong, the south of Huludao of Liaoning and Yanbian of Jilin. Longyou 6, Longyou 7, Longyou 8 and Longyou 9 were the wintering-safe B. rapa varieties. PMID:26995911

  8. Winter meso-scale shear front in the Yellow Sea and its sedimentary effects

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Qiao, Lulu; Li, Guangxue

    2016-02-01

    In this paper, the authors explored the presence of shear fronts between the Yellow Sea Coastal Current (YSCC) and the monsoon-strengthened Yellow Sea Warm Current (YSWC) in winter and their sedimentary effects within the shear zone based on a fully validated numerical model. This work added the wind force to a tidal model during simulating the winter baroclinic circulation in the Yellow Sea. The results indicate that the YSWC is significantly strengthened by wind-driven compensation due to a northeast monsoon during winter time. When this warm current encounters the North Shandong-South Yellow Sea coastal current, there is a strong reverse shear action between the two current systems, forming a reverse-S-shaped shear front that begins near 34°N in the south and extends to approximately 38°N, with an overall length of over 600 km. The main driving force for the formation of this shear front derives from the circulation system with the reverse flow. In the shear zone, temperature and salinity gradients increase, flow velocities are relatively small and the flow direction on one side of the shear zone is opposite to that on the other side. The vertical circulation structure is complicated, consisting of a series of meso- and small-scale anti-clockwise eddies. Particularly, this shear effect significantly hinders the horizontal exchange of coastal sediments carried by warm currents, resulting in fine sediments deposition due to the weak hydrodynamic regime.

  9. Effect of winter cold duration on spring phenology of the orange tip butterfly, Anthocharis cardamines.

    PubMed

    Stålhandske, Sandra; Lehmann, Philipp; Pruisscher, Peter; Leimar, Olof

    2015-12-01

    The effect of spring temperature on spring phenology is well understood in a wide range of taxa. However, studies on how winter conditions may affect spring phenology are underrepresented. Previous work on Anthocharis cardamines (orange tip butterfly) has shown population-specific reaction norms of spring development in relation to spring temperature and a speeding up of post-winter development with longer winter durations. In this experiment, we examined the effects of a greater and ecologically relevant range of winter durations on post-winter pupal development of A. cardamines of two populations from the United Kingdom and two from Sweden. By analyzing pupal weight loss and metabolic rate, we were able to separate the overall post-winter pupal development into diapause duration and post-diapause development. We found differences in the duration of cold needed to break diapause among populations, with the southern UK population requiring a shorter duration than the other populations. We also found that the overall post-winter pupal development time, following removal from winter cold, was negatively related to cold duration, through a combined effect of cold duration on diapause duration and on post-diapause development time. Longer cold durations also lead to higher population synchrony in hatching. For current winter durations in the field, the A. cardamines population of southern UK could have a reduced development rate and lower synchrony in emergence because of short winters. With future climate change, this might become an issue also for other populations. Differences in winter conditions in the field among these four populations are large enough to have driven local adaptation of characteristics controlling spring phenology in response to winter duration. The observed phenology of these populations depends on a combination of winter and spring temperatures; thus, both must be taken into account for accurate predictions of phenology. PMID:27069602

  10. COLD FRONTS AND GAS SLOSHING IN GALAXY CLUSTERS WITH ANISOTROPIC THERMAL CONDUCTION

    SciTech Connect

    ZuHone, J. A.; Markevitch, M.; Lee, D.

    2013-01-10

    Cold fronts in cluster cool cores should be erased on short timescales by thermal conduction, unless protected by magnetic fields that are 'draped' parallel to the front surfaces, suppressing conduction perpendicular to the sloshing fronts. We present a series of MHD simulations of cold front formation in the core of a galaxy cluster with anisotropic thermal conduction, exploring a parameter space of conduction strengths parallel and perpendicular to the field lines. Including conduction has a strong effect on the temperature distribution of the core and the appearance of the cold fronts. Though magnetic field lines are draping parallel to the front surfaces, preventing conduction directly across them, the temperature jumps across the fronts are nevertheless reduced. The geometry of the field is such that the cold gas below the front surfaces can be connected to hotter regions outside via field lines along directions perpendicular to the plane of the sloshing motions and along sections of the front that are not perfectly draped. This results in the heating of this gas below the front on a timescale of a Gyr, but the sharpness of the density and temperature jumps may nevertheless be preserved. By modifying the gas density distribution below the front, conduction may indirectly aid in suppressing Kelvin-Helmholtz instabilities. If conduction along the field lines is unsuppressed, we find that the characteristic sharp jumps seen in Chandra observations of cold front clusters do not form. Therefore, the presence of cold fronts in hot clusters is in contradiction with our simulations with full Spitzer conduction. This suggests that the presence of cold fronts in hot clusters could be used to place upper limits on conduction in the bulk of the intracluster medium. Finally, the combination of sloshing and anisotropic thermal conduction can result in a larger flux of heat to the core than either process in isolation. While still not sufficient to prevent a cooling

  11. Magnetized thermal conduction fronts. [between hot and cold astrophysical plasma

    NASA Technical Reports Server (NTRS)

    Balbus, S. A.

    1986-01-01

    The evolution of planar thermal conduction fronts in the presence of a dynamically weak, but otherwise self-consistent, magnetic field is considered. The field is assumed to be connected and untangled. In the diffusion limit for the thermal conductivity, these fronts exhibit self-similar behavior, even in the presence of a field. The role of the field is restricted to channeling the heat flux along its lines of force, and it enters into the problem as a dimensionless angle variable. 'Combing' (or opening) of insulating field lines by the evaporative flow is explicitly demonstrated. Unless the field is nearly perpendicular to the front normal in the hot gas, insulating effects are not profound. Self-similarity breaks down if the front becomes saturated, and under certain conditions magnetized saturated conduction fronts cannot propagate: the solution characteristics of the wave equation form caustics. The physical resolution is the advent of two-fluid (nonlocal) heating. Such Coulomb-heated fronts are expected to be relatively rare in typical astrophysical systems. The large-scale effects of a magnetic field on cloud evaporation in the interstellar medium are briefly discussed, and it is suggested that these fields preclude the presence of time-independent evaporative solutions. Thermal interfaces may then continue to evolve until radiative cooling halts their development; large tracts of warm 10,000 K gas may result.

  12. A Link Between Reduced Arctic Sea Ice and Cold Winter Extremes over Northern Continents

    NASA Astrophysics Data System (ADS)

    Semenov, V. A.; Petoukhov, V.

    2009-04-01

    The recent overall Northern Hemisphere warming was accompanied by several severe northern continental winters, in particular extremely cold winter 2005/2006 in Europe and northern Asia. Here we show that these cold extremes might be favored by anomalous sea ice reduction in the Barents and Kara Seas in the Eastern Arctic. Atmospheric general circulation model simulations demonstrate that strong anti-cyclonic circulation over the Polar Ocean and easterly advection over northern continents may arise as a response to anomalous atmospheric heating. This brings about a continental-scale winter cooling reaching 1.5˚C, with more than three times increased probability of cold winter extremes. Our results imply that several recent harsh winters do not conflict the global warming picture but rather supplement it, being in agreement with the large-scale atmospheric circulation response to Arctic sea ice reduction.

  13. Decreasing but still significant facilitation effect of cold-season macrophytes on wetlands purification function during cold winter.

    PubMed

    Zou, Xiangxu; Zhang, Hui; Zuo, Jie; Wang, Penghe; Zhao, Dehua; An, Shuqing

    2016-01-01

    To identify the facilitation effect of a cool-season aquatic macrophyte (FEam) for use in effluent purification via constructed floating wetlands (CFWs) and to determine the possible pathways used during a winter period with an average temperature of less than 5 °C, pilot-scale CFWs were planted with the cold-season macrophyte Oenanthe clecumbens and were operated as batch systems. Although some leaves withered, the roots retained relatively high levels of activity during the winter, which had average air and water temperatures of 3.63 and 5.04 °C, respectively. The N and P removal efficiencies in CFWs decreased significantly in winter relative to those in late autumn. The presence of cool-season plants resulted in significant improvements in N and P removal, with a FEam of 15.23-25.86% in winter. Microbial N removal accounted for 71.57% of the total N removed in winter, and the decrease in plant uptake was the dominant factor in the wintertime decrease in N removal relative to that in late autumn. These results demonstrate the importance of cold-season plants in CFWs for the treatment of secondary effluent during cold winters. PMID:27245709

  14. Decreasing but still significant facilitation effect of cold-season macrophytes on wetlands purification function during cold winter

    NASA Astrophysics Data System (ADS)

    Zou, Xiangxu; Zhang, Hui; Zuo, Jie; Wang, Penghe; Zhao, Dehua; An, Shuqing

    2016-06-01

    To identify the facilitation effect of a cool-season aquatic macrophyte (FEam) for use in effluent purification via constructed floating wetlands (CFWs) and to determine the possible pathways used during a winter period with an average temperature of less than 5 °C, pilot-scale CFWs were planted with the cold-season macrophyte Oenanthe clecumbens and were operated as batch systems. Although some leaves withered, the roots retained relatively high levels of activity during the winter, which had average air and water temperatures of 3.63 and 5.04 °C, respectively. The N and P removal efficiencies in CFWs decreased significantly in winter relative to those in late autumn. The presence of cool-season plants resulted in significant improvements in N and P removal, with a FEam of 15.23–25.86% in winter. Microbial N removal accounted for 71.57% of the total N removed in winter, and the decrease in plant uptake was the dominant factor in the wintertime decrease in N removal relative to that in late autumn. These results demonstrate the importance of cold-season plants in CFWs for the treatment of secondary effluent during cold winters.

  15. Changes in Arctic warm and cold spell occurrence during winter and summer

    NASA Astrophysics Data System (ADS)

    Matthes, Heidrun; Rinke, Annette; Dethloff, Klaus

    2016-04-01

    In the Arctic, climate change manifests with the strongest warming trends on the globe, especially in the cold season, associated with Arctic Amplification. However, climate change is not restricted to mean temperature but also expresses itself in changes of temperature extremes. It is under debate if climate extremes change similarly strong, and what mechanisms apply. Our study provides detailed regional information about two selected temperature extreme indices in the Arctic, namely warm and cold spells in winter and summer. Both indices detect lasting cold respectively warm periods that are based on extreme temperatures: cold nights as days where the daily minimum temperature is below the 10th percentile of minimum temperatures and warm day times where the daily maximum temperature is above the 90th percentile of maximum temperatures. We analyze the temporal evolution and variability of warm and cold spells from 1979-2013, based on daily station data and the ERA-Interim reanalysis. Calculated trends from both datasets suggest a widespread decrease of cold spells in winter and summer of up to -4 days/decade, with regional patches where trends are statistically significant throughout the Arctic. Winter trends are spatially heterogeneous, the reanalysis also shows small areas with statistically significant increases of cold spells throughout Siberia. Calculated changes in warm spells from both datasets are mostly small throughout the Arctic (below ± 1 day/decade) and statistically not significant. Remarkable exceptions are the Lena river basin in winter with a statistically significant decrease of up to 1.5 days/decade and areas in Scandinavia with statistically significant increases of up to 2.5 days/decade in winter and summer (again from both datasets). Changes in both warm and cold spells may be caused by two separate mechanisms: changes in occurrence of the underlying extremes (changes in the number of cold nights and warm daytimes) or changes in the temporal

  16. Unusually cold and dry winters increase mortality in Australia.

    PubMed

    Huang, Cunrui; Chu, Cordia; Wang, Xiaoming; Barnett, Adrian G

    2015-01-01

    Seasonal patterns in mortality have been recognised for decades, with a marked excess of deaths in winter, yet our understanding of the causes of this phenomenon is not yet complete. Research has shown that low and high temperatures are associated with increased mortality independently of season; however, the impact of unseasonal weather on mortality has been less studied. In this study, we aimed to determine if unseasonal patterns in weather were associated with unseasonal patterns in mortality. We obtained daily temperature, humidity and mortality data from 1988 to 2009 for five major Australian cities with a range of climates. We split the seasonal patterns in temperature, humidity and mortality into their stationary and non-stationary parts. A stationary seasonal pattern is consistent from year-to-year, and a non-stationary pattern varies from year-to-year. We used Poisson regression to investigate associations between unseasonal weather and an unusual number of deaths. We found that deaths rates in Australia were 20-30% higher in winter than summer. The seasonal pattern of mortality was non-stationary, with much larger peaks in some winters. Winters that were colder or drier than a typical winter had significantly increased death risks in most cities. Conversely summers that were warmer or more humid than average showed no increase in death risks. Better understanding the occurrence and cause of seasonal variations in mortality will help with disease prevention and save lives. PMID:25460613

  17. The impact of winter cold weather on acute myocardial infarctions in Portugal.

    PubMed

    Vasconcelos, João; Freire, Elisabete; Almendra, Ricardo; Silva, Giovani L; Santana, Paula

    2013-12-01

    Mortality due to cardiovascular diseases shows a seasonal trend that can be associated with cold weather. Portugal is the European country with the highest excess winter mortality, but nevertheless, the relationship between cold weather and health is yet to be assessed. The main aim of this study is to identify the contribution of cold weather to cardiovascular diseases within Portugal. Poisson regression analysis based on generalized additive models was applied to estimate the influence of a human-biometeorological index (PET) on daily hospitalizations for myocardial infarction. The main results revealed a negative effect of cold weather on acute myocardial infarctions in Portugal. For every degree fall in PET during winter, there was an increase of up to 2.2% (95% CI = 0.9%; 3.3%) in daily hospital admissions. This paper shows the need for public policies that will help minimize or, indeed, prevent exposure to cold. PMID:23410618

  18. High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

    NASA Astrophysics Data System (ADS)

    Büttger, Heike; Nehls, Georg; Witte, Sophia

    2011-12-01

    Mortality of introduced Pacific oysters ( Crassostrea gigas) was studied in the northern Wadden Sea in response to an ice winter. After a decade of mild winters, in January and February 2010, the first severe winter occurred since the Pacific oysters became dominant on former intertidal blue mussel ( Mytilus edulis) beds in the North-Frisian Wadden Sea. After the ice winter, mortality of Pacific oysters on densely populated beds in the List tidal basin reached about 90%, indicating much higher losses in comparison to former mild winters. At lower densities between the islands of Amrum and Föhr, oysters were less or even not affected. Although Pacific oysters are assumed to be very tolerant to frost, the duration of cold water- and air temperatures accompanied by mechanical stress of the ice burden might have caused the high mortality in the winter 2009/2010 in formerly dense beds.

  19. Effects of cold front passage on turbulent fluxes over a large inland water

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Liu, H.

    2011-12-01

    Turbulent fluxes of sensible and latent heat over a large inland water in southern USA were measured using the eddy covariance method through the year of 2008. In addition, net radiation, air temperatures and relative humidity, and water temperature in different depths were also measured. The specific objective of this study is to examine effects of a cold front passage on the surface energy fluxes. For the typical cold front event selected from April 11 to 14, air temperature decreased by 16°C, while surface temperature only dropped 6°C. Atmospheric vapor pressure decreased by 1.6 kPa, while that in the water-air interface dropped 0.7 kPa. The behavior difference in the water-air interface was caused by the passage of cold, dry air masses immediately behind the cold front. During the cold front event, sensible heat and latent heat flux increased by 171 W m-2 and 284 W m-2, respectively. Linear aggression analysis showed that the sensible heat flux was proportional to the product of wind speed and the temperature gradient of water-air interface, with a correlation coefficient of 0.95. Latent heat flux was proportional to the product of wind speed and vapor pressure difference between the water surface and overlaying atmosphere, with a correlation coefficient of 0.81. Also, the correlations between both fluxes and the wind speed were weak. This result indicated that the strong wind associated with the cold front event contributed to the turbulent mixing, which indirectly enhanced surface energy exchange between the water surface and the atmosphere. The relationship between the water heat storage energy and turbulent fluxes was also examined.

  20. THE EFFECT OF ANISOTROPIC VISCOSITY ON COLD FRONTS IN GALAXY CLUSTERS

    SciTech Connect

    ZuHone, J. A.; Markevitch, M.; Biffi, V.

    2015-01-10

    Cold fronts—contact discontinuities in the intracluster medium (ICM) of galaxy clusters—should be disrupted by Kelvin-Helmholtz (K-H) instabilities due to the associated shear velocity. However, many observed cold fronts appear stable. This opens the possibility of placing constraints on microphysical mechanisms that stabilize them, such as the ICM viscosity and/or magnetic fields. We performed exploratory high-resolution simulations of cold fronts arising from subsonic gas sloshing in cluster cores using the grid-based Athena MHD code, comparing the effects of isotropic Spitzer and anisotropic Braginskii viscosity (expected in a magnetized plasma). Magnetized simulations with full Braginskii viscosity or isotropic Spitzer viscosity reduced by a factor f ∼ 0.1 are both in qualitative agreement with observations in terms of suppressing K-H instabilities. The rms velocity of turbulence within the sloshing region is only modestly reduced by Braginskii viscosity. We also performed unmagnetized simulations with and without viscosity and find that magnetic fields have a substantial effect on the appearance of the cold fronts, even if the initial field is weak and the viscosity is the same. This suggests that determining the dominant suppression mechanism of a given cold front from X-ray observations (e.g., viscosity or magnetic fields) by comparison with simulations is not straightforward. Finally, we performed simulations including anisotropic thermal conduction, and find that including Braginskii viscosity in these simulations does not significantly affect the evolution of cold fronts; they are rapidly smeared out by thermal conduction, as in the inviscid case.

  1. Cold War: Flora's Undercover Agents. A Campus Winter Field Trip to Illustrate That Plants Do Indeed Thermoregulate.

    ERIC Educational Resources Information Center

    DeGolier, Teresa

    2002-01-01

    Proposes using a winter field trip to explore how various plants on a campus thermoregulate. Describes techniques for determining the location of cold stresses in plants and how plants manage to deal with the cold stresses. (DDR)

  2. Generation of seiches by cold fronts over the southern North Sea

    NASA Astrophysics Data System (ADS)

    de Jong, M. P. C.; Holthuijsen, L. H.; Battjes, J. A.

    2003-04-01

    Seiches affecting the Port of Rotterdam are generated in the Southern North Sea. Their generation is investigated with observations and numerical simulations. A wavelet analysis of the observations, both at sea and in the harbor, shows that low-frequency energy (0.1-2.0 mHz) does indeed occur at sea prior to each seiche event in Rotterdam. An analysis of 6 years of weather charts indicates that all 51 seiche events in this period (with amplitude exceeding 0.25 m) coincided with the passage of a low-pressure weather system. Some of these low-pressure systems included a sharp cold front (classical or ana), whereas others included a more diffuse cold front (split or kata). Numerical simulations with a hydrodynamic model driven by meteorological observations reproduced the seiches for situations with the sharp cold fronts correctly. The seiches that were simulated for situations with the gradual cold fronts do not agree with the observations, which is ascribed to the inadequate atmospheric forcing of the hydrodynamical model.

  3. Observations of a cold front with strong vertical undulations during the ARM RCS-IOP

    SciTech Connect

    Starr, D.O`C.; Whiteman, D.N.; Melfi, S.H.

    1996-04-01

    Passage of a cold front was observed on the night of April 14-15, 1994, during the Atmospheric Radiation Measurement (ARM) Remote Cloud Sensing (RCS) Intensive Observatios Period (IOP) at the Southern Great Plains Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma. The observations are described.

  4. A CloudSat-CALIPSO View of Cloud and Precipitation Properties Across Cold Fronts over the Global Oceans

    NASA Technical Reports Server (NTRS)

    Naud, Catherine M.; Posselt, Derek J.; van den Heever, Susan C.

    2015-01-01

    The distribution of cloud and precipitation properties across oceanic extratropical cyclone cold fronts is examined using four years of combined CloudSat radar and CALIPSO lidar retrievals. The global annual mean cloud and precipitation distributions show that low-level clouds are ubiquitous in the post frontal zone while higher-level cloud frequency and precipitation peak in the warm sector along the surface front. Increases in temperature and moisture within the cold front region are associated with larger high-level but lower mid-/low level cloud frequencies and precipitation decreases in the cold sector. This behavior seems to be related to a shift from stratiform to convective clouds and precipitation. Stronger ascent in the warm conveyor belt tends to enhance cloudiness and precipitation across the cold front. A strong temperature contrast between the warm and cold sectors also encourages greater post-cold-frontal cloud occurrence. While the seasonal contrasts in environmental temperature, moisture, and ascent strength are enough to explain most of the variations in cloud and precipitation across cold fronts in both hemispheres, they do not fully explain the differences between Northern and Southern Hemisphere cold fronts. These differences are better explained when the impact of the contrast in temperature across the cold front is also considered. In addition, these large-scale parameters do not explain the relatively large frequency in springtime post frontal precipitation.

  5. Charge and discharge of polar cold air mass in northern hemispheric winter

    NASA Astrophysics Data System (ADS)

    Kanno, Yuki; Abdillah, Muhammad Rais; Iwasaki, Toshiki

    2015-09-01

    This study shows the variability of polar cold air mass amount below potential temperature of 280 K, and north of 45°N can be understood with a concept of charge and discharge, where anomalously large daily discharge indicates an intermittent occurrence of cold air outbreak. The polar cold air mass amount north of 45°N gradually charges up due to diabatic cooling but dramatically discharges due to cold air outbreak with a pulse width of about 5 days. Cold air outbreaks tend to bring colder winter in East Asia and the east coast of North America, while warmer winter prevails on the northern side of these regions. The cold air mass amount south of 45°N increases just after a cold air outbreak but returns to the normal level soon because of its life time of about 3 days. Therefore, monthly mean of total cold air mass amount in the Northern Hemisphere is negatively correlated with the monthly mean discharge.

  6. Cold-Active Winter Rye Glucanases with Ice-Binding Capacity12

    PubMed Central

    Yaish, Mahmoud W.F.; Doxey, Andrew C.; McConkey, Brendan J.; Moffatt, Barbara A.; Griffith, Marilyn

    2006-01-01

    Extracellular pathogenesis-related proteins, including glucanases, are expressed at cold temperatures in winter rye (Secale cereale) and display antifreeze activity. We have characterized recombinant cold-induced glucanases from winter rye to further examine their roles and contributions to cold tolerance. Both basic β-1,3-glucanases and an acidic β-1,3;1,4-glucanase were expressed in Escherichia coli, purified, and assayed for their hydrolytic and antifreeze activities in vitro. All were found to be cold active and to retain partial hydrolytic activity at subzero temperatures (e.g. 14%–35% at −4°C). The two types of glucanases had antifreeze activity as measured by their ability to modify the growth of ice crystals. Structural models for the winter rye β-1,3-glucanases were developed on which putative ice-binding surfaces (IBSs) were identified. Residues on the putative IBSs were charge conserved for each of the expressed glucanases, with the exception of one β-1,3-glucanase recovered from nonacclimated winter rye in which a charged amino acid was present on the putative IBS. This protein also had a reduced antifreeze activity relative to the other expressed glucanases. These results support the hypothesis that winter rye glucanases have evolved to inhibit the formation of large, potentially fatal ice crystals, in addition to having enzymatic activity with a potential role in resisting infection by psychrophilic pathogens. Glucanases of winter rye provide an interesting example of protein evolution and adaptation aimed to combat cold and freezing conditions. PMID:16815958

  7. Cold fronts in the Colombian Caribbean Sea and their relationship to extreme wave events

    NASA Astrophysics Data System (ADS)

    Ortiz-Royero, J. C.; Otero, L. J.; Restrepo, J. C.; Ruiz, J.; Cadena, M.

    2013-11-01

    Extreme ocean waves in the Caribbean Sea are commonly related to the effects of storms and hurricanes during the months of June through November. The collapse of 200 m of the Puerto Colombia pier in March 2009 revealed the effects of meteorological phenomena other than storms and hurricanes that may be influencing the extreme wave regime in the Colombian Caribbean. The marked seasonality of these atmospheric fronts was established by analyzing the meteorological-marine reports of the Instituto de Hidrología, Meteorología y Estudios Ambientales of Colombia (IDEAM, based on its initials in Spanish) and the Centro de Investigación en Oceanografía y Meteorología of Colombia (CIOH, based on its initials in Spanish) during the last 16 yr. The highest number of cold fronts was observed during the months of January, February, and March, with 6 fronts occurring per year. An annual trend was observed and the highest number of fronts occurred in 2010 (20 in total); moreover, an annual strong relationship between the maximum average wave values and the cold fronts in the central zone of the Colombian Caribbean during the first three months of the year was established. In addition, the maximum values of the significant height produced by the passage of cold fronts during the last 16 yr were identified. Although the Colombian Caribbean has been affected by storms and hurricanes in the past, this research allows us to conclude that there is a strong relationship between cold fronts and the largest waves in the Colombian Caribbean during the last 16 yr, which have caused damage to coastal infrastructure. We verified that the passage of a cold front corresponded to the most significant extreme wave event of the last two decades in the Colombian Caribbean, which caused the structural collapse of the Puerto Colombia pier, located near the city of Barranquilla, between 5 and 10 March 2009. This information is invaluable when evaluating average and extreme wave regimes for the

  8. Recent changes in Arctic temperature extremes: warm and cold spells during winter and summer

    NASA Astrophysics Data System (ADS)

    Matthes, Heidrun; Rinke, Annette; Dethloff, Klaus

    2015-11-01

    In the Arctic, climate change manifests with the strongest warming trends on the globe, especially in the cold season. It is under debate if climate extremes change similarly strong. Our study provides detailed regional information about two selected temperature extreme indices in the Arctic, namely warm and cold spells in winter and summer. We analyze their temporal evolution and variability from 1979-2013, based on daily station data and ERA-Interim reanalysis. Calculated trends from both datasets suggest a widespread decrease of cold spells in winter and summer of up to -4 days/decade, with regional patches where trends are statistically significant throughout the Arctic. Winter trends are spatially heterogeneous, the reanalysis also shows small areas with statistically significant increases of cold spells throughout Siberia. Calculated changes in warm spells from both datasets are mostly small throughout the Arctic (less than ±1 day/decade) and statistically not significant. Remarkable exceptions are the Lena river basin in winter with a statistically significant decrease of up to -1.5 days/decade and areas in Scandinavia with statistically significant increases of up to 2.5 days/decade in winter and summer (again from both datasets). From the analysis of spell lengths, we find that there are no shifts from longer to shorter spells or vice versa with time, but long cold spells (events lasting for more than 15 days) disappear almost completely after the year 2000. There is a distinct inter-annual and decadal variability in the spells, which hinders the detection of significant trends for all spell categories in all regions.

  9. The climatology of East Asian winter monsoon and cold surges from 1979--1995 NCEP/NCAR reanalyses

    SciTech Connect

    Yi Zhang; Sperber, K.; Boyle, J.

    1996-04-01

    The East Asian winter monsoon, which is associated with the Siberian high and active cold surges, is one of the most energetic monsoon circulation systems. The dramatic shift of northeasterlies and the outbreak of cold surges dominate the winter weather and local climate in the East Asian region, and may exert a strong impact on the extratropical and tropical planetary-scale circulations and influence the SSTs in the tropical western Pacific. General characteristics of the winter monsoon and cold surges and their possible link with tropical disturbances are revealed in many observational studies. Little attention has been given to the climatological aspects of the winter monsoon and cold surges. The purpose of this study is to compile and document the East Asian mean winter circulation, and present the climatology of cold surges and the Siberian high based on the 1979--1995 NCEP/NCAR reanalyses. Of particular interest is the interannual variation of winter monsoon circulation and cold surge events. Given that the cold surge activity and the Indonesian convection are much reduced during the 1982--83 period, one of the goals is to determine whether there exists a statistically significant relationship between ENSO and the interannual variation of winter monsoon and cold surges.

  10. [Cold tolerance and wintering cultivation effect of different Welsh onion varieties].

    PubMed

    Su, Hua; Xu, Kun; Liu, Wei; Xu, Ligong

    2006-10-01

    With Welsh onion Zhangqiu as the contrast, this paper measured the physiological indices including electrolyte leakage, malondialdehyde content, protective enzyme activity, chlorophyll content, photosynthetic rate and root vitality of two introduced Welsh onion varieties Chunwei and Changhao, and identified their cold tolerance and wintering cultivation effect. The results showed that during wintering cultivation, all test Welsh onion varieties suffered low temperature stress, which led the electrolyte leakage and malondialdehyde content arrived at the maximum, while the chlorophyll content and photosynthetic rate dropped to the bottom at 15 January. At this time, the function data of physiological indices were 0. 452, 0. 364, and 0. 226 for Chuowei, Changbao and Zhangqiu, respectively, suggesting that Chunwei had stronger cold tolerance, followed by Changbao, and Zhangqiu. The bolting rate of Chunwei, Changbao and Zhangqiu when harvested was 0, 35.2% and 81.0% , respectively. Although the biological yield of Changbao was 25.67% and 52. 94% higher than that of Chunwei and Zhangqiu, respectively, the economic yield of Chunwei was the highest (5.49 kg m2) , with an increment of 18. 57% than Changbao, and that of Zhangqiu was only 0. 86 kg x m(-2) It could be concluded that Chonwei was fit to cultivate in low tunnel in winter, while Zhangqiu was weaker in cold tolerance and not fit to wintering cultivation. PMID:17209388

  11. Winter cold-tolerance thresholds in field-grown Miscanthus hybrid rhizomes

    PubMed Central

    Peixoto, Murilo de Melo; Friesen, Patrick Calvin; Sage, Rowan F.

    2015-01-01

    The cold tolerance of winter-dormant rhizomes was evaluated in diploid, allotriploid, and allotetraploid hybrids of Miscanthus sinensis and Miscanthus sacchariflorus grown in a field setting. Two artificial freezing protocols were tested: one lowered the temperature continuously by 1°C h–1 to the treatment temperature and another lowered the temperature in stages of 24h each to the treatment temperature. Electrolyte leakage and rhizome sprouting assays after the cold treatment assessed plant and tissue viability. Results from the continuous-cooling trial showed that Miscanthus rhizomes from all genotypes tolerated temperatures as low as –6.5 °C; however, the slower, staged-cooling procedure enabled rhizomes from two diploid lines to survive temperatures as low as –14 °C. Allopolyploid genotypes showed no change in the lethal temperature threshold between the continuous and staged-cooling procedure, indicating that they have little ability to acclimate to subzero temperatures. The results demonstrated that rhizomes from diploid Miscanthus lines have superior cold tolerance that could be exploited to improve performance in more productive polyploid lines. With expected levels of soil insulation, low winter air temperatures should not harm rhizomes of tolerant diploid genotypes of Miscanthus in temperate to sub-boreal climates (up to 60°N); however, the observed winter cold in sub-boreal climates could harm rhizomes of existing polyploid varieties of Miscanthus and thus reduce stand performance. PMID:25788733

  12. A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents

    NASA Astrophysics Data System (ADS)

    Petoukhov, Vladimir; Semenov, Vladimir A.

    2010-11-01

    The recent overall Northern Hemisphere warming was accompanied by several severe northern continental winters, as for example, extremely cold winter 2005-2006 in Europe and northern Asia. Here we show that anomalous decrease of wintertime sea ice concentration in the Barents-Kara (B-K) seas could bring about extreme cold events like winter 2005-2006. Our simulations with the ECHAM5 general circulation model demonstrate that lower-troposphere heating over the B-K seas in the Eastern Arctic caused by the sea ice reduction may result in strong anticyclonic anomaly over the Polar Ocean and anomalous easterly advection over northern continents. This causes a continental-scale winter cooling reaching -1.5°C, with more than 3 times increased probability of cold winter extremes over large areas including Europe. Our results imply that several recent severe winters do not conflict the global warming picture but rather supplement it, being in qualitative agreement with the simulated large-scale atmospheric circulation realignment. Furthermore, our results suggest that high-latitude atmospheric circulation response to the B-K sea ice decrease is highly nonlinear and characterized by transition from anomalous cyclonic circulation to anticyclonic one and then back again to cyclonic type of circulation as the B-K sea ice concentration gradually reduces from 100% to ice free conditions. We present a conceptual model that may explain the nonlinear local atmospheric response in the B-K seas region by counter play between convection over the surface heat source and baroclinic effect due to modified temperature gradients in the vicinity of the heating area.

  13. Snow cover and late fall movement influence wood frog survival during an unusually cold winter.

    PubMed

    O'Connor, Jason H; Rittenhouse, Tracy A G

    2016-07-01

    Understanding how organisms will respond to altered winter conditions is hampered by a paucity of information on the winter ecology for many species. Amphibians are sensitive to environmental temperature and moisture conditions and may be vulnerable to changes in winter climate. We used a combination of radio telemetry and field enclosures to monitor survival of the freeze-tolerant wood frog (Lithobates sylvaticus) during the unusually cold winter of 2013-2014. We experimentally manipulated snow cover to determine the effect of snow removal on winter survival. In addition, we placed a group of untracked frogs at locations used by tracked frogs prior to long-distance late fall movement to investigate whether late fall movement entailed survival consequences. Winter survival was highest (75.3 %) among frogs at post-movement locations that received natural snow cover. The odds of surviving the winter for frogs in the snow removal treatment was only 21.6 % that of frogs in the natural snow treatment. Likewise, paired frogs placed at pre-fall movement locations had only 35.1 % the odds of surviving as tracked frogs at post-fall movement locations. A comparison of a priori models that included microhabitat conditions measured at wood frog overwintering locations revealed that the minimum temperature experienced and the depth of the frog in the substrate explained additional variation in winter survival. Our results suggest that acute exposure to lethal temperature conditions is the most likely cause of mortality during this study, rather than energy exhaustion or desiccation. They also demonstrate the importance of snow cover to the winter survival of wood frogs. PMID:26497126

  14. Cold temperature increases winter fruit removal rate of a bird-dispersed shrub.

    SciTech Connect

    Charles Kwit; Douglas J. Levey; Cathryn H. Greenberg; Scott F. Pearson; John P. McCarty; Sarah Sargent

    2004-01-10

    Kwit, C., D. J. Levey; C. H. Greenberg, S. F. Pearson, J.P. McCarty, and S. Sargent. Cold temperature increases winter fruit removal rate of a bird-dispersed shrub. Oecologia. 139:30-34. Abstract: We tested the hypothesis that winter removal rates of fruits of wax myrtle, Myrica cerifera, are higher in colder winters. Over a 9-year period, we monitored M. cerifera fruit crops in 13 0.1-ha study plots in South Carolina, U.S.A. Peak ripeness occurred in November, whereas peak removal occurred in the coldest months, December and January. Mean time to fruit removal within study plots was positively correlated with mean winter temperatures, thereby supporting our hypothesis. This result, combined with the generally low availability of winter arthropods, suggests that fruit abundance may play a role in determining winter survivorship and distribution of permanent resident and short-distance migrant birds. From the plant's perspective, it demonstrates inter-annual variation in the temporal component of seed dispersal, with possible consequences for post-dispersal seed and seedling ecology.

  15. 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.

  16. Heat production in cold and long scotophase acclimated and winter acclimatized rodents

    NASA Astrophysics Data System (ADS)

    Haim, A.; Fourie, F. Le R.

    1980-09-01

    Heat production by means of oxygen consumptionVo2 (at Ta = 6° C, 25° C, 30° C, and 32° C) and non-shivering thermogenesis (NST) were studied in individuals of a diurnal rodent ( Rhabdomys pumilio) and a nocturnal rodent ( Praomys natalensis). The studied mice were acclimated to cold at Ta=8°C with a photoperiod of LD 12:12. On the otherhand specimens of these two species were acclimated at Ta=25°C with a long scotophase LD8:16. The results were compared with a control group (Ta=25° C, LD 12:12) and winter acclimatized individuals of both species.Vo2 in cold acclimated mice of both species was significantly increased when compared to the control group and was even higher than the winter acclimatized group when measured below the lower critical temperature. Long scotophase acclimated mice of both species also increased their oxygen consumption significantly when compared to the control group. NST was significantly increased in long scotophase acclimated mice from both species when compared to the control group. The results of this study indicate that the effects of acclimation to long scotophase are similar to those of cold acclimation. As changes in photoperiod are regular, it may be assumed that heat production mechanisms in acclimatization to winter will respond to changes in photoperiodicity.

  17. Dissipation of excess excitation energy of the needle leaves in Pinus trees during cold winters

    NASA Astrophysics Data System (ADS)

    Zhang, AO; Cui, Zhen-Hai; Yu, Jia-Lin; Hu, Zi-Ling; Ding, Rui; Ren, Da-Ming; Zhang, Li-Jun

    2016-05-01

    Photooxidative damage to the needle leaves of evergreen trees results from the absorption of excess excitation energy. Efficient dissipation of this energy is essential to prevent photodamage. In this study, we determined the fluorescence transients, absorption spectra, chlorophyll contents, chlorophyll a/b ratios, and relative membrane permeabilities of needle leaves of Pinus koraiensis, Pinus tabulaeformis, and Pinus armandi in both cold winter and summer. We observed a dramatic decrease in the maximum fluorescence (F m) and substantial absorption of light energy in winter leaves of all three species. The F m decline was not correlated with a decrease in light absorption or with changes in chlorophyll content and chlorophyll a/b ratio. The results suggested that the winter leaves dissipated a large amount of excess energy as heat. Because the cold winter leaves had lost normal physiological function, the heat dissipation depended solely on changes in the photosystem II supercomplex rather than the xanthophyll cycle. These findings imply that more attention should be paid to heat dissipation via changes in the photosystem complex structure during the growing season.

  18. How predictable is the winter extremely cold days over temperate East Asia?

    NASA Astrophysics Data System (ADS)

    Luo, Xiao; Wang, Bin

    2016-07-01

    Skillful seasonal prediction of the number of extremely cold day (NECD) has considerable benefits for climate risk management and economic planning. Yet, predictability of NECD associated with East Asia winter monsoon remains largely unexplored. The present work estimates the NECD predictability in temperate East Asia (TEA, 30°-50°N, 110°-140°E) where the current dynamical models exhibit limited prediction skill. We show that about 50 % of the total variance of the NECD in TEA region is likely predictable, which is estimated by using a physics-based empirical (P-E) model with three consequential autumn predictors, i.e., developing El Niño/La Niña, Eurasian Arctic Ocean temperature anomalies, and geopotential height anomalies over northern and eastern Asia. We find that the barotropic geopotential height anomaly over Asia can persist from autumn to winter, thereby serving as a predictor for winter NECD. Further analysis reveals that the sources of the NECD predictability and the physical basis for prediction of NECD are essentially the same as those for prediction of winter mean temperature over the same region. This finding implies that forecasting seasonal mean temperature can provide useful information for prediction of extreme cold events. Interpretation of the lead-lag linkages between the three predictors and the predictand is provided for stimulating further studies.

  19. Links between solar wind variations, the global electric circuit, and winter cyclone vorticity, and possibly to cold winters in Europe

    NASA Astrophysics Data System (ADS)

    Tinsley, B. A.

    2011-12-01

    There are a number of inputs to the atmosphere and the climate system that are modulated by solar activity that have their only common feature the modulation of the ionosphere-earth current density (Jz) in the global electric circuit, and to which it has now been shown there are small atmospheric responses in winter storm vorticity, surface pressure, and cloud cover. Similar responses are found to internal atmospheric inputs that modulate Jz. An inductive mechanism for initial storm electrification is described that responds to Jz and provides space charge for aerosol particles and droplets throughout the updraft region. The charge on droplets and aerosol particles, by the process of charge modulation of aerosol scavenging (CMAS), increases condensation nuclei concentrations and shifts their distributions to smaller average sizes. This produces smaller and more numerous droplets, and as shown by Rosenfeld et al (2008), delays initial precipitation and increases ice production and the vigor of the storm updraft. For baroclinic storms the additional latent heat release and updraft velocity increases storm vorticity. The result depends on both aerosol characteristics and the Jz variation. The cumulative effect of winter storm intensification, for example in the Icelandic Low cyclogenesis region, responding to Jz changes, is to increase blocking in the Atlantic Ocean. Such blocking reduces the flow of relatively warm moist ocean air onto Europe, while increasing the incidence of outbreaks of cold, dry, Arctic air. The possibility is examined that increases in cosmic ray flux and in Jz, at times of decadal and longer minima in solar activity, contributes to the changes in atmospheric circulation and the resulting unusually severe winters in the UK and Europe such as have occurred during extended solar minima in the late 17th century and early 21st century.

  20. What caused the recent ``Warm Arctic, Cold Continents'' trend pattern in winter temperatures?

    NASA Astrophysics Data System (ADS)

    Sun, Lantao; Perlwitz, Judith; Hoerling, Martin

    2016-05-01

    The emergence of rapid Arctic warming in recent decades has coincided with unusually cold winters over Northern Hemisphere continents. It has been speculated that this "Warm Arctic, Cold Continents" trend pattern is due to sea ice loss. Here we use multiple models to examine whether such a pattern is indeed forced by sea ice loss specifically and by anthropogenic forcing in general. While we show much of Arctic amplification in surface warming to result from sea ice loss, we find that neither sea ice loss nor anthropogenic forcing overall yield trends toward colder continental temperatures. An alternate explanation of the cooling is that it represents a strong articulation of internal atmospheric variability, evidence for which is derived from model data, and physical considerations. Sea ice loss impact on weather variability over the high-latitude continents is found, however, to be characterized by reduced daily temperature variability and fewer cold extremes.

  1. Cold-induced bradycardia in man during sleep in Arctic winter nights

    NASA Astrophysics Data System (ADS)

    Buguet, A. G. C.

    1987-03-01

    Two young male Caucasians volunteered for a study on the effects of cold exposure during night sleep in winter in the Arctic. The 14-day experiment was divided in three consecutive periods, baseline (2 nights), cold exposure (10 night) and recovery (2 nights). Both baseline and recovery data were obtained in neutral thermal conditions in a laboratory. The subjects slept in a sleeping bag under an unheated tent during the cold exposure. Apart from polysomnographic and body temperature recordings, electrocardiograms were taken through a telemetric system for safety purposes. Heart rates were noted at 5-min intervals and averaged hourly. In both environmental conditions, heart rate decreased within the first two hours of sleep. Comparison of the data obtained during cold exposure vs. thermal neutrality revealed lower values of heart rate in the cold, while body temperatures remained within normal range. This cold-induced bradycardia supervening during night sleep is discussed in terms of the occurrence of a vagal reflex preventing central blood pressure to rise.

  2. Changes in winter cold surges over Southeast China: 1961 to 2012

    NASA Astrophysics Data System (ADS)

    Ou, Tinghai; Chen, Deliang; Jeong, Jee-Hoon; Linderholm, Hans W.; Zhou, Tianjun

    2015-02-01

    The present study investigates the overall changes in occurrences of winter cold surges over Southeast China for the period 1961-2012, using instrumental observations, reanalysis and model simulation datasets. Based on objectively defined criteria, cold surges were classified into 3 types according to their dynamical origin as inferred from daily evolution patterns of surface pressure systems with a focus on the Siberian High (SH): type A with an amplification of a quasi-stationary SH associated with high-pressure anomalies over the Ural mountains, type B with a developing SH associated with fast traveling upper-level waves, and type C with a high-pressure originated in the Arctic. Examination of the long-term change in cold surge occurrences shows different interdecadal variations among the 3 types. During 1961-2012, type A events (37.8%) decreased, while type B events, accounting for the majority (52.5%) of total winter cold surges, increased slightly. The contribution by type C to the total occurrence of the cold surges was small (8.8%) compared to that of A and B, but it became more frequent in the latest decade, related to the tendency of the Arctic Oscillation (AO) being more in its negative phase. Overall, we found slightly increased occurrences of cold surges over Southeast China since the early 1980s, despite the weakened SH intensity and warmer mean temperature compared to previous decades. The climate model projections of the phase 5 of the Coupled Model Intercomparison Project (CMIP5) suggests similar trend in the late 21st century under warmer climate.

  3. MERGING COLD FRONTS IN THE GALAXY PAIR NGC 7619 AND NGC 7626

    SciTech Connect

    Randall, S. W.; Jones, C.; Kraft, R.; Forman, W. R.; O'Sullivan, E.

    2009-05-10

    We present results from Chandra observations of the galaxy pair NGC 7619 and NGC 7626, the two dominant members of the Pegasus group. The X-ray images show a brightness edge associated with each galaxy, which we identify as merger cold fronts. The edges are sharp, and the axes of symmetry of the edges are roughly antiparallel, suggesting that these galaxies are falling toward one another in the plane of the sky. The detection of merger cold fronts in each of the two dominant member galaxies implies a merging subgroup scenario, since the alternative is that the galaxies are falling into a preexisting {approx}1 keV halo without a dominant galaxy of its own, and such objects are not observed. We estimate the three-dimensional velocities from the cold fronts and, using the observed radial velocities of the galaxies, show that the velocity vectors are indeed most likely close to the plane of the sky, with a relative velocity of {approx}1190 km s{sup -1}. The relative velocity is consistent with what is expected from the infall of two roughly equal mass subgroups whose total viral mass equals that of the Pegasus group. We conclude that the Pegasus cluster is most likely currently forming from a major merger of two subgroups, dominated by NGC 7619 and NGC 7626. NGC 7626 contains a strong radio source, consisting of a core with two symmetric jets, and radio lobes. Although we find no associated structure in the X-ray surface brightness map, the temperature map reveals a clump of cool gas just outside the southern lobe, presumably entrained by the lobe, and possibly an extension of cooler gas into the lobe itself. The jet axis is parallel with the projected direction of motion of NGC 7626 (inferred from the symmetry axis of the merger cold front), and the southern leading jet is foreshortened as compared to the northern trailing one, possibly due to the additional ram pressure encountered by the forward jet.

  4. A physical analysis of the severe 2013/2014 cold winter in North America

    NASA Astrophysics Data System (ADS)

    Yu, Bin; Zhang, Xuebin

    2015-10-01

    The severe 2013/2014 cold winter has been examined in the context of the previous 55 winters using the National Centers for Environmental Prediction reanalysis data for the period 1960-2014. North America is dominated by pronounced cold anomalies over the Great Plains and Great Lakes in December 2013 and February 2014 but exhibits an east-west contrast pattern with warm anomalies over most of the North American West in January 2014. A relevant temperature index, defined as land surface temperature anomalies averaged over (40°-60°N, 105°-80°W), reveals a warming trend as well as interannual variability with a significant power peak of 6.0 years. While 2013/2014 was the second coldest winter during 1960-2014, it is the coldest one in the linearly detrended series, with a negative anomaly of 2.63 standard deviations. This indicates that the long-term warming has made the 2013/2014 winter less severe than it could have been. The temperature and circulation variability in association with the zonally symmetric variability of the polar vortex projects weakly on the corresponding anomalies in the 2013/2014 winter, whereas the variability associated with the principal mode of North American surface temperature projects strongly on the corresponding anomalies in the winter. This mode is associated with a sea surface temperature (SST) pattern of significant anomalies over the North Pacific and North Atlantic middle and high latitudes. The anomalous atmospheric circulation shows an anticyclonic anomaly over the Gulf of Alaska-Bering Sea and a cyclonic anomaly downstream over North America. It bears resemblance to the North Pacific Oscillation/Western Pacific pattern and drives the SST in the North Pacific. Over western-central Canada and the northern U.S., below-average heights are associated with above-normal precipitation, implying enhanced upward vertical motion and variation of local cloud forcing, leading to a variation of the surface energy budget dominated by

  5. Adaptive Changes in ATPase Activity in the Cells of Winter Wheat Seedlings during Cold Hardening

    PubMed Central

    Jian, Ling-Cheng; Sun, Long-Hua; Dong, He-Zhu

    1982-01-01

    A cytochemical study of ATPase activity in the cells of cold hardened and nonhardened winter wheat (Triticum aestivum L. cv. Nongke No. 1) seedlings was carried out by electron microscopic observation of lead phosphate precipitation. ATPase activity associated with various cellular organelles was altered during cold hardening. (a) At 22°C, high plasmalemma ATPase activity was observed in both cold hardened and nonhardened tissues; at 5°C, high activity of plasmalemma ATPase was observed in hardened tissues, but not in unhardened tissues. (b) In nonhardened tissues, tonoplast and vacuoles did not exhibit high ATPase activity at either 22 or 5°C, while in hardened tissues high activity was observed at both temperatures. (c) At 5°C, ATPase activity of nucleoli and chromatin was decreased in hardened tissues, but not in nonhardened tissues. It is suggested that adaptive changes in ATPase activity associated with a particular cellular organelle or membrane may be associated with the development of frost resistance of winter wheat seedlings. Images Fig. 1 Fig. 2 Fig. 3 PMID:16662432

  6. Rapid uplift of nonmethane hydrocarbons in a cold front over central Europe

    NASA Astrophysics Data System (ADS)

    Purvis, R. M.; Lewis, A. C.; Carney, R. A.; McQuaid, J. B.; Arnold, S. R.; Methven, J.; Barjat, H.; Dewey, K.; Kent, J.; Monks, P. S.; Carpenter, L. J.; Brough, N.; Penkett, S. A.; Reeves, C. E.

    2003-04-01

    The vertical distribution of 21 C2-C7 nonmethane hydrocarbons (NMHCs) has been determined in planetary boundary layer (PBL) and free tropospheric (FT) air over central Europe under a range of meteorological conditions. High-frequency whole air sampling was conducted on board the U.K. Meteorological Office C-130 Hercules aircraft during the European Export of Precursors and Ozone by Long-Range Transport (EXPORT) experiment in August 2000. When vertical transport by large-scale flow or convection was weak, the expected large concentration gradient between the PBL and FT was observed for all short and medium lifetime hydrocarbons (e.g., average iso-butane, PBL 100 pptV, FT 6 pptV). During periods of strong convective activity associated with the passage of a cold front, a rapid uplift of reactive carbon from the boundary layer to the mid free troposphere was observed. Using changing ratios of hydrocarbons with different atmospheric lifetimes, a timescale for transport during this event was determined. Hydrocarbon lifetime measurements suggest that in certain regions of the system, it is convective transport embedded within the cold front rather than larger-scale advection along the warm conveyor belt that is dominant in transporting ozone precursors into the free troposphere.

  7. The effect of moving cold fronts over Central Europe to the variability of the ionosphere

    NASA Astrophysics Data System (ADS)

    Potuznikova, Katerina; Koucka Knizova, Petra; Boska, Josef; Sindelarova, Tereza; Mosna, Zbysek

    2015-04-01

    Cold fronts represent well known source of atmospheric waves, (especially short and medium scale AGW - acoustic gravity waves), that are able to propagate up to the ionospheric heights. In our study we focus on the effects of the transitions of cold front over the region of Central Europe on the variations of the ionosphere. We concentrate on periods of low solar and geomagnetic activity. Neutral atmosphere data are compared with the wave-like oscillations in the E and F layer. Our tropospheric data comprise synoptic maps on of 500 hPa and 850 hPa geopotential heights. Within ionospheric data we search for variability that is linked to the tropospheric disturbances. The ionospheric parameters (electron concentration and corresponding height) we analyse by the wavelet transform method. The Modern HF digisonde DPS-4 D (Digisonde Portable Sounder), which is in operation at the Pruhonice observatory (49.59 N; 14.33 E) of the Institute of Atmospheric Physics, Prague (IAP) since 2004, represents an excellent source of the ionospheric data for Central Europe. Pruhonice digisonde usually operates in standard mode - one ionogram and electron density profie N(h) each 15 minutes. Besides that, data from several european stations of the digisonde world network (data from Juliusruhe, Chilton, Brusel, Roma and Tortosa digisonde stations) are included in the study.

  8. Windowpane flounder (Scophthalmus aquosus) and winter flounder (Pseudopleuronectes americanus) responses to cold temperature extremes in a Northwest Atlantic estuary

    NASA Astrophysics Data System (ADS)

    Wilber, Dara H.; Clarke, Douglas G.; Alcoba, Catherine M.; Gallo, Jenine

    2016-01-01

    The effect of climate variability on flatfish includes not only the effects of warming on sensitive life history stages, but also impacts from more frequent or unseasonal extreme cold temperatures. Cold weather events can affect the overwintering capabilities of flatfish near their low temperature range limits. We examined the responses of two flatfish species, the thin-bodied windowpane (Scophthalmus aquosus) and cold-tolerant winter flounder (Pseudopleuronectes americanus), to variable winter temperatures in a Northwest Atlantic estuary using abundance and size data collected during a monitoring study, the Aquatic Biological Survey, conducted from 2002 to 2010. Winter and spring abundances of small (50 to 120 mm total length) juvenile windowpane were positively correlated with adult densities (spawning stock) and fall temperatures (thermal conditions experienced during post-settlement development for the fall-spawned cohort) of the previous year. Windowpane abundances in the estuary were significantly reduced and the smallest size class was nearly absent after several consecutive years with cold (minimum temperatures < 1 °C) winters. Interannual variation in winter flounder abundances was unrelated to the severity of winter temperatures. A Paulik diagram illustrates strong positive correlations between annual abundances of sequential winter flounder life history stages (egg, larval, Age-1 juvenile, and adult male) within the estuary, reflecting residency within the estuary through their first year of life. Temperature variables representing conditions during winter flounder larval and post-settlement development were not significant factors in multiple regression models exploring factors that affect juvenile abundances. Likewise, densities of predators known to consume winter flounder eggs and/or post-settlement juveniles were not significantly related to interannual variation in winter flounder juvenile abundances. Colder estuarine temperatures through the

  9. Detecting spring after a long winter: coma or slow vigilance in cold, hypoxic turtles?

    PubMed Central

    Madsen, Jesper G.; Wang, Tobias; Beedholm, Kristian; Madsen, Peter T.

    2013-01-01

    Many freshwater turtle species can spend the winter submerged in ice-covered lakes by lowering their metabolism, and it has been proposed that such severe metabolic depression render these turtles comatose. This raises the question of how they can detect the arrival of spring and respond in a sensible way to sensory information during hibernation. Using evoked potentials from cold or hypoxic turtles exposed to vibration and light, we show that hibernating turtles maintain neural responsiveness to light stimuli during prolonged hypoxia. Furthermore, turtles held under hibernation conditions for 14 days increase their activity when exposed to light or elevated temperatures, but not to vibration or increased oxygen. It is concluded that hibernating turtles are not comatose, but remain vigilant during overwintering in cold hypoxia, allowing them to respond to the coming of spring and to adjust their behaviour to specific sensory inputs. PMID:24108677

  10. Dynamical and thermodynamical analysis of the South China Sea winter cold tongue

    NASA Astrophysics Data System (ADS)

    Thompson, Bijoy; Tkalich, Pavel; Malanotte-Rizzoli, Paola; Fricot, Bastien; Mas, Juliette

    2015-12-01

    Spatial distribution of the South China Sea (SCS) surface temperature shows strong cold anomalies over the Sunda Shelf during the boreal winter season. The band of low sea surface temperature (SST) region located south/southeast of Vietnam is called as the winter cold tongue (CT) in the SCS. Using observational and re-analysis datasets a comprehensive investigation of the dynamical and thermodynamical processes associated with the evolution of SCS CT is performed in this study. The role and relative importance of wind-driven ocean transports, air-sea heat fluxes and oceanic processes are explored. The north-south Sverdrup transport demonstrates strong southward transport during the northeast monsoon period aiding the SST cooling by bringing relatively cold water from the north. The zonal and meridional Ekman transports exhibit relatively weak westward and northward transports to the CT region during this period. The study suggests that wind-driven ocean transports have a significant role in regulating the shape and spatial extent of the CT. The heat budget analysis revealed that net surface heat flux decrease during the northeast monsoon acts as the primary cooling mechanism responsible for the development of the SCS CT, while the horizontal advection of cold water by the western boundary current along the coast of Vietnam plays a secondary role. The wintertime SST anomalies over the CT region are significantly linked to the Nino3 index. Most of the warming/cooling events in the SST anomalies coincide with the El Nino/La Nina phenomena in the Pacific Ocean.

  11. Does winter warming enhance cold CO2 emission from temperate continental soils?

    NASA Astrophysics Data System (ADS)

    Kurganova, Irina; Lopes de Gerenyu, Valentin; Khoroshaev, Dmitry

    2016-04-01

    In subboreal and temperate regions, the cold season generally lasts more than 3 months of the year, influencing the carbon cycle in terrestrial ecosystems. The permanent snow pack plays an important role in the functioning of the ecosystem, especially in temperate continental regions, preventing frost penetration into the soil. The extent and duration of the permanent snow pack are predicted to decrease markedly in transitional seasons for many boreal and subboreal regions during the next 50 years. This study focused on: (i) assessment of current winter climate trends in the Moscow region pertaining to the continental temperate region, (ii) comparison of soil temperature regimes at different snow pack depths, (iii) estimation of cold CO2 fluxes from soils under various frozen regime and vegetation cover, and (iv) the contribution of freezing-thawing events to the total cold CO2 emission from soils in the temperate continental region. An experiment with regulated snow cover was established on grassland and bare soil (Luvisols Haplic, Moscow region, 54o50'N, 37o36'E; continental temperate climate). The following winter scenarios were foreseen: (1) reference plot, designated "Ref", with natural depth of snow cover, (2) no-frost, "NoFr" (simulation of deep snow cover using artificial heat insulation material), and (3) no-snow, "NoSn" (without snow cover). We observed inverse trends as the air temperature increased and precipitation decreased, which resulted in a 1-month prolongation of the snow-free period and a decrease in the snow pack over the last 20 years. Soil freezing significantly reduced the cold CO2 fluxes from soils: by 10-70% in the bare areas and by up to double that amount in the grass plots. There were six freezing-thawing cycles (FTC; 1-7 weeks' duration) from October 2014 to early April 2015, which induced CO2 emission pulses of varying intensity. The highest peaks of CO2 emission rate (3-30-fold increase compared to the pre-thawing period) were

  12. Cold Tolerance and Sex-Dependent Hypothermia May Explain Winter Sexual Segregation in a Farmland Bird.

    PubMed

    Powolny, Thibaut; Bretagnolle, Vincent; Dupoué, Andréaz; Lourdais, Olivier; Eraud, Cyril

    2016-01-01

    Migration is an important event in the life cycle of many organisms, but considerable intraspecific variation may occur in its timing and/or destination, resulting in sexual segregation during wintering periods. In this study, we tested the body size hypothesis, or cold tolerance hypothesis, which predicts that body size dimorphism modulates metabolic costs associated with cold climate. Using the Eurasian skylark, we first investigated whether this species showed sexual differential migration. Then we explored the body size hypothesis by experimentally testing the effect of low ambient temperature (Ta) on both metabolic rate (MR) and body temperature (Tb). We tested for sex-related differences in metabolism and in energy-saving mechanism (hypothermia). We found clear differential migration by sex in skylark wintering populations, with a male-biased sex ratio decreasing toward southern latitudes. Measurements on captive birds at 20°, 6°, and -5°C demonstrated a significant increase in MR when Ta decreased, but there is no difference between sexes. While both males and females reduced their Tb overnight, Tb reduction was more pronounced in females exposed to the coldest temperature treatment. In addition, we found that individuals with the most reduced Tb lost less body weight during the night, suggesting that Tb reduction may help minimize energy expenditure when conditions become constraining. Our study suggests that functional mechanisms may be involved in latitudinal segregation between sexes and supports the hypothesis that sex-specific physiological strategies and thermal tolerance may explain segregation between sexes. PMID:27082725

  13. Nitrogen oxides measurements in an Amazon site and enhancements associated with a cold front

    NASA Astrophysics Data System (ADS)

    Cordova, A. M.; Longo, K.; Freitas, S.; Gatti, L. V.; Artaxo, P.; Procópio, A.; Silva Dias, M. A. F.; Freitas, E. D.

    2004-05-01

    An intensive atmospheric chemistry study was carried out in a pristine Amazonian forest site (Balbina), Amazonas state, Brazil during the 2001 wet season, as part of the LBA/CLAIRE 2001 (The Large Scale Biosphere Atmosphere Experiment in Amazonia/Cooperative LBA Airborne Regional Experiment) field campaign. Measurements of nitrogen oxide (NO), nitrogen dioxide (NO2) and ozone (O3) were performed simultaneously with aerosol particles and black carbon concentrations and meteorological parameters observations. Very low trace gases and aerosol concentrations are typically observed at this pristine tropical site. During the measurement period, there was a three-day episode of enhancement of NO2 and black carbon concentration. NO2 concentration reached a maximum value of 4 ppbv, which corresponds to three times the background concentration observed for this site. Black carbon concentration increased from the approximated 100 ng/m3 average value to a 200 ng/m3 maximum during the same period. Biomass burning spots were detected southward, between latitudes 15 to 10° S, 5-6 days before this episode from GOES-8 WF_ABBA (Wildfire Automated Biomass Burning Algorithm). An atmospheric numerical simulation of the whole measurement period was carried out using the RAMS model coupled to a biomass burning emission and transport model. The simulation results pictured a smoke transport event from Central Brazil associated to an approach of a mid-latitude cold front, reinforcing the hypothesis of biomass burning products being long-range transported from the South by the cold front and crossing the Equator. This transport event shows how the pristine atmosphere pattern in Amazonia is impacted by biomass burning emissions from sites very far away.

  14. Geographic variation in Bar-headed geese Anser indicus: connectivity of wintering and breeding grounds across a broad front.

    USGS Publications Warehouse

    Takekawa, John Y.; Heath, Shane R.; Douglas, David C.; Perry, William M.; Javed, Salim; Newman, Scott H.; Suwal, Rajendra N.; Rahman, Asad R.; Choudhury, Binod C.; Prosser, Diann J.; Yan, Baoping; Hou, Yuansheng; Batbayar, Nyambayar; Natsagdorj, Tseveenmayadag; Bishop, Charles M.; Butler, Patrick J.; Frappell, Peter B.; Milsom, William K.; Scott, Graham R.; Hawkes, Lucy A.; Wikelski, Martin

    2009-01-01

    The connectivity and frequency of exchange between sub-populations of migratory birds is integral to understanding population dynamics over the entire species' range. True geese are highly philopatric and acquire lifetime mates during the winter, suggesting that the number of distinct sub-populations may be related to the number of distinct wintering areas. In the Bar-headed Goose Anser indicus, a species found exclusively in Central Asia, the connectivity between breeding and wintering areas is not well known. Their migration includes crossing a broad front of the Himalaya Cordillera, a significant barrier to migration for most birds. Many Bar-headed Geese fly to breeding areas on the Tibetan-Qinghai Plateau (TQP), the highest plateau in the world. From 2005-2008, 60 Bar-headed Geese were captured and marked with satellite transmitters in Nepal (n = 2), India (n = 6), China (n = 29), and Mongolia (n = 23) to examine their migration and distribution. Distinct differences were observed in their migration corridors and timing of movements, including an apparent leap-frog migration pattern for geese from Mongolia. Measurements of geese from Mongolia were larger than their counterparts from China, providing some evidence of morphological differences. Alteration of habitats in China, including the warming effects of climate change on glaciers increasing runoff to TQP wetlands, may be changing goose migration patterns and timing. With the exception of one individual, all geese from Qinghai Lake, China wintered in the southern TQP near Lhasa, and their increasing numbers in that region may be related to the effects of climate change and agricultural development. Thus, our findings document both morphological and geographical variation in sub-populations of Bar-headed Geese, but their resilience to environmental change may be lost if migratory short-stopping results in larger congregations restricted to a smaller number of wintering areas.

  15. Research aircraft observations of the mesoscale and microscale structure of a cold front over the eastern Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Bond, Nicholas A.; Shapiro, M. A.

    1991-01-01

    The structure of an oceanic cold front is described on the basis of research aircraft observations taken during the Ocean Storms field experiment. Synoptic and mesoscale analyses compare the structure of an upper-level jet-front system observed slightly downstream from the wind speed maximum to its structure in the upstream entrance region. Stratospheric potential vorticity and ozone were found within the frontal zone down to about 800 mb. Microscale analyses of the front near the sea surface were carried out for a portion of the front having the signature of a 'rope' cloud in satellite imagery. A narrow (less than 1 km) zone of upward motion (about 4 m/s) and of horizontal shear (about 0.01/s) characterized the front near the surface. Significant alongfront variability was found, including lateral displacements in the frontal zone where there were weaker updrafts.

  16. Spatial use by wintering greater white-fronted geese relative to a decade of habitat change in California's Central Valley

    USGS Publications Warehouse

    Ackerman, J.T.; Takekawa, J.Y.; Orthmeyer, D.L.; Fleskes, J.P.; Yee, J.L.; Kruse, K.L.

    2006-01-01

    We investigated the effect of recent habitat changes in California's Central Valley on wintering Pacific greater white-fronted geese (Anser albifrons frontalis) by comparing roost-to-feed distances, distributions, population range sizes, and habitat use during 1987-1990 and 1998-2000. These habitat changes included wetland restoration and agricultural land enhancement due to the 1990 implementation of the Central Valley Joint Venture, increased land area used for rice (Oryza sativa) production, and the practice of flooding, rather than burning, rice straw residues for decomposition because of burning restrictions enacted in 1991. Using radiotelemetry, we tracked 192 female geese and recorded 4,516 locations. Geese traveled shorter distances between roosting and feeding sites during 1998-2000 (24.2 ?? 2.2 km) than during 1987-1990 (32.5 ?? 3.4 km); distance traveled tended to decline throughout winter during both decades and varied among watershed basins. Population range size was smaller during 1998-2000 (3,367 km2) than during 1987-1990 (5,145 km2), despite a 2.2-fold increase in the size of the Pacific Flyway population of white-fronted geese during the same time period. The population range size also tended to increase throughout winter during both decades. Feeding and roosting distributions of geese also differed between decades; geese shifted into basins that had the greatest increases in the amount of area in rice production (i.e., American Basin) and out of other basins (i.e., Delta Basin). The use of rice habitat for roosting (1987-1990: 40%, 1998-2000: 54%) and feeding (1987-1990: 57%, 1998-2000: 72%) increased between decades, whereas use of wetlands declined for roosting (1987-1990: 36%, 1998-2000: 31%) and feeding (1987-1990: 22%, 1998-2000: 12%). Within postharvested rice habitats, geese roosted and fed primarily in burned rice fields during 1987-1990 (roost: 43%, feed: 34%), whereas they used flooded rice fields during 1998-2000 (roost: 78%, feed: 64

  17. Improved management of winter operations to limit subsurface contamination with degradable deicing chemicals in cold regions.

    PubMed

    French, Helen K; van der Zee, Sjoerd E A T M

    2014-01-01

    This paper gives an overview of management considerations required for better control of deicing chemicals in the unsaturated zone at sites with winter maintenance operations in cold regions. Degradable organic deicing chemicals are the main focus. The importance of the heterogeneity of both the infiltration process, due to frozen ground and snow melt including the contact between the melting snow cover and the soil, and unsaturated flow is emphasised. In this paper, the applicability of geophysical methods for characterising soil heterogeneity is considered, aimed at modelling and monitoring changes in contamination. To deal with heterogeneity, a stochastic modelling framework may be appropriate, emphasizing the more robust spatial and temporal moments. Examples of a combination of different field techniques for measuring subsoil properties and monitoring contaminants and integration through transport modelling are provided by the SoilCAM project and previous work. Commonly, the results of flow and contaminant fate modelling are quite detailed and complex and require post-processing before communication and advising stakeholders. The managers' perspectives with respect to monitoring strategies and challenges still unresolved have been analysed with basis in experience with research collaboration with one of the case study sites, Oslo airport, Gardermoen, Norway. Both scientific challenges of monitoring subsoil contaminants in cold regions and the effective interaction between investigators and management are illustrated. PMID:24281673

  18. Leucine Transport in Cells Isolated from Cold-Hardened and Nonhardened Winter Rye 1

    PubMed Central

    Barran, Leslie R.; Singh, Jas

    1982-01-01

    The properties of the leucine transport systems of cells isolated from dark-grown cold-hardened and nonhardened winter rye (Secale cereale L. cv. Puma) epicotyls were remarkably similar. After 1 hour of incubation, leucine was accumulated in the cells 80- to 100-fold above that of the external medium, but the transported leucine was not metabolized. Approximately one-third of the accumulated leucine was present in the vacuole after 40 minutes of incubation. At 25°C, efflux of leucine from the vacuole was 6 to 10 times slower than it was from the cytoplasm, while at 5°C efflux from the cells was inhibited. The apparent Km and Vmax for leucine uptake for both types of cells were of the order of 20 to 60 micromolar and 0.5 to 1.3 nanomoles per minute per 106 cells. The pH and temperature optima for both types of cells were 5 and 25°C, respectively. The leucine transport system for these cells was relatively specific for amino acids lacking either bulky or charged groups on the amino acid side chains. Arrhenius plots for leucine uptake by hardened and nonhardened cells showed discontinuities at 13°C, and the energies of activation were similar. The results suggests that biochemical changes which occur in rye cells upon cold hardening did not result in an observable perturbation of the properties of the leucine transport system. PMID:16662298

  19. Daily photosynthetic and C-export patterns in winter wheat leaves during cold stress and acclimation.

    PubMed

    Leonardos, Evangelos D.; Savitch, Leonid V.; Huner, Norman P. A.; Oquist, Gunnar; Grodzinski, Bernard

    2003-04-01

    Diurnal patterns of whole-plant and leaf gas exchange and 14C-export of winter wheat acclimated at 20 and 5 degrees C were determined. The 5 degrees C-acclimated plants had lower relative growth rates, smaller biomass and leaf area, but larger specific leaf weight than 20 degrees C plants. Photosynthetic rates in 20 degrees C and 5 degrees C-acclimated leaves were similar; however, daytime export from 5 degrees C-acclimated leaves was 45% lower. Photosynthesis and export remained steady in 20 degrees C and 5 degrees C-acclimated leaves during the daytime. By comparison, photosynthesis in 5 degrees C-stressed leaves (20 degrees C-acclimated plants exposed to 5 degrees C 12 h before and during measurements) declined from 70 to 50% of the 20 degrees C-acclimated leaves during the daytime, while export remained constant at 35% of the 20 degrees C-acclimated and 60% of the 5 degrees C-acclimated leaves. At high light and CO2, photosynthesis and export increased in both 20 degrees C and 5 degrees C-acclimated leaves, but rates in 5 degrees C-stressed leaves remained unchanged. At all conditions daytime export was greater than nighttime export. Taken together, during cold acclimation photosynthesis was upregulated, whereas export was only partially increased. We suggest that this reflects a requirement of cold-acclimated plants to both sustain an increased leaf metabolic demand while concomitantly supporting translocation of photoassimilates to overwintering sinks. PMID:12675742

  20. Research on winter-hardiness: deacclimation resistance, reacclimation ability, photoprotection strategies, and a cold acclimation protocol design

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Freezing is a major environmental stress during the annual cycle of temperate zone perennials. Freeze- injury can occur due to mid-winter temperatures that are colder than the tolerance threshold of a tissue / plant or due to untimely freezing temperatures before cold acclimation (development of fre...

  1. MAGNETOHYDRODYNAMIC SIMULATIONS OF THE FORMATION OF COLD FRONTS IN CLUSTERS OF GALAXIES: EFFECTS OF ANISOTROPIC VISCOSITY

    SciTech Connect

    Suzuki, Kentaro; Ogawa, Takayuki; Matsumoto, Yosuke; Matsumoto, Ryoji E-mail: ogawa@astro.s.chiba-u.ac.jp E-mail: matumoto@astro.s.chiba-u.ac.jp

    2013-05-10

    We carried out three-dimensional magnetohydrodynamic simulations to study the effects of plasma viscosity on the formation of sharp discontinuities of density and temperature distributions, cold fronts, in clusters of galaxies. By fixing the gravitational potential that confines the cool, dense plasma in a moving subcluster, we simulated its interaction with the hot, lower density plasma around the subcluster. At the initial state, the intracluster medium (ICM) is assumed to be threaded by uniform magnetic fields. The enhancement of plasma viscosity along the direction of magnetic fields is incorporated as anisotropic viscosity depending on the direction of magnetic fields. We found that the Kelvin-Helmholtz instability at the surface of the subcluster grows even in models with anisotropic viscosity, because its effects on the velocity shear across the magnetic field lines are suppressed. We also found that magnetic fields around the interface between the subcluster and ICM are amplified even in the presence of viscosity, while magnetic fields behind the subcluster are amplified up to {beta}{sup -1} {approx} 0.01 in models with viscosity, whereas they are amplified up to {beta}{sup -1} {approx} 0.1 in models without viscosity, where {beta} is the ratio of gas pressure to magnetic pressure.

  2. Storms or cold fronts? What is really responsible for the extreme waves regime in the Colombian Caribbean coast

    NASA Astrophysics Data System (ADS)

    Otero, L. J.; Ortiz-Royero, J. C.; Ruiz-Merchan, J. K.; Higgins, A. E.; Henriquez, S. A.

    2015-05-01

    On Friday, 7 March 2009, a 200 m-long section of the tourist pier in Puerto Colombia collapsed under the impact of the waves generated by a cold front in the area. The aim of this study is to determine the contribution and importance of cold fronts and storms on extreme waves in different areas of the Colombian Caribbean to determine the degree of the threat posed by the flood processes to which these coastal populations are exposed and the actions to which coastal engineering constructions should be subject. In the calculation of maritime constructions, the most important parameter is the wave's height; therefore, it is necessary to definitively know the design wave height to which a coastal engineering structure should be resistant. This wave height varies according to the return period considered. Using Gumbel's extreme value methodology, the significant height values for the study area were calculated. The methodology was evaluated using data from the re-analysis of the spectral NOAA Wavewatch III (WW3) model for 15 points along the 1600 km of the Colombia Caribbean coast (continental and insular) of the last 15 years. The results demonstrated that the extreme waves caused by tropical cyclones and cold fronts have different effects along the Colombian Caribbean coast. Storms and hurricanes are of greater importance in the Guajira Peninsula (Alta Guajira). In the central area formed by Baja Guajira, Santa Marta, Barranquilla, and Cartagena, the strong influence of cold fronts on extreme waves is evident. On the other hand, in the southern region of the Colombian Caribbean coast, from the Gulf of Morrosquillo to the Gulf of Urabá, even though extreme waves are lower than in the previous regions, extreme waves are dominated mainly by the passage of cold fronts. Extreme waves in the San Andrés and Providencia insular region present a different dynamic from that in the continental area due to its geographic location. The wave heights in the extreme regime are

  3. Lesser White-fronted (Anser erythropus) and Greater White-fronted (A. albifrons) Geese wintering in Greek wetlands are not threatened by Pb through shot ingestion.

    PubMed

    Aloupi, Maria; Kazantzidis, Savas; Akriotis, Triantaphyllos; Bantikou, Evangelia; Hatzidaki, Victoria-Ourania

    2015-09-15

    Fecal lead (Pb) levels were investigated in the threatened European population of the Lesser White-fronted Goose (LWfG, Anser erythropus) and of the non-threatened Greater White-fronted Goose (GWfG, Anser albifrons) wintering in two wetland areas in northern Greece in order to assess the potential risk from Pb exposure. Fecal, soil and food plant samples were analyzed. Levels of Pb were normalized using Al concentrations in order to separate the effect of possible ingestion of Pb shot from that of soil or sediment accidentally ingested with food. All concentrations are expressed on a dry weight basis. Geometric means of Pb content in the feces of LWfG were 6.24 mg/kg at Evros Delta and 7.34 mg/kg at Lake Kerkini (maximum values of 28.61 mg/kg and 36.68 mg/kg, respectively); for fecal samples of GWfG geometric means were 2.39 mg/kg at Evros Delta and 6.90 mg/kg at Kerkini (corresponding maximum values of 25.09 mg/kg and 42.26 mg/kg). Soil Pb was in the range of 5.2-60.2mg/kg (geometric mean = 22.6 mg/kg) for the Evros Delta and between 13.4 and 64.9 mg/kg (geometric mean=28.1mg/kg) for Kerkini. A general linear model fitted to the data showed that Pb levels were very closely dependent on Al levels in the feces from both species and at both sites indicating soil or sediment were the only significant source of Pb; species and site, as well as their interaction, were not statistically significant factors. For both species and at both sites exposure to Pb was evidently very mild and the observed levels of Pb were well below the proposed thresholds for lethal or sublethal effects of Pb poisoning. Soil ingestion appeared to gradually increase from October to December for LWfG at Kerkini, corresponding to a gradual depletion of their food source. PMID:25965041

  4. Characterization and effects of cold fronts in the Colombian Caribbean Coast and their relationship to extreme wave events

    NASA Astrophysics Data System (ADS)

    Ortiz-Royero, J. C.; Otero, L. J.; Restrepo, J. C.; Ruiz, J.; Cadena, M.

    2013-07-01

    Extreme ocean waves in the Caribbean Sea are commonly related to the effects of storms and hurricanes during the months of June through November. The collapse of 200 m of the Puerto Colombia pier in March 2009 revealed the effects of meteorological phenomena other than storms and hurricanes that may be influencing the extreme wave regime in the Colombian Caribbean. The marked seasonality of these atmospheric fronts was established by analyzing the meteorological-marine reports of Instituto de Hidrología, Meteorología y Estudios Ambientales of Colombia (IDEAM, based on its initials in Spanish) and Centro de Investigación en Oceanografía y Meteorología of Colombia (CIOH, based on its initials in Spanish). The highest occurrences were observed during the months of January, February, and March, with 6 fronts occurring per year. An annual trend was not observed, although the highest number of fronts occurred in 2010 (20 in total). An annual strong relationship between the maximum average wave values and the cold fronts, in the central zone of the Colombian Caribbean during the first three months of the year was established. In addition, the maximum values of the significant height produced by the passage of cold fronts during the last 16 yr were identified. Although the Colombian Caribbean has been affected by storms and hurricanes in the past, this research allows us to conclude that, there is a strong relationship between cold fronts and the largest waves in the Colombian Caribbean during the last 16 yr, which have caused damage to coastal infrastructure. We verified that the passage of a cold front corresponded to the most significant extreme wave event of the last two decades in the Colombian Caribbean, which caused the structural collapse of the Puerto Colombia pier, located near the city of Barranquilla, between 5 and 10 March 2009. This information is invaluable when evaluating average and extreme wave regimes for the purpose of informing the design of

  5. SLOSHING COLD FRONTS IN GALAXY GROUPS AND THEIR PERTURBING DISK GALAXIES: AN X-RAY, OPTICAL, AND RADIO CASE STUDY

    SciTech Connect

    Gastaldello, Fabio; Di Gesu, Laura; Ghizzardi, Simona; Rossetti, Mariachiara; Giacintucci, Simona; Girardi, Marisa; Roediger, Elke; Brighenti, Fabrizio; Buote, David A.; Humphrey, Philip J.; Eckert, Dominique; Ettori, Stefano; Mathews, William G.

    2013-06-10

    We present a combined X-ray, optical, and radio analysis of the galaxy group IC 1860 using the currently available Chandra and XMM data, multi-object spectroscopy data from the literature, and Giant Metrewave Radio Telescope (GMRT) data. The Chandra and XMM imaging and spectroscopy reveal two surface brightness discontinuities at 45 and 76 kpc shown to be consistent with a pair of cold fronts. These features are interpreted as due to sloshing of the central gas induced by an off-axis minor merger with a perturber. This scenario is further supported by the presence of a peculiar velocity of the central galaxy IC 1860 and the identification of a possible perturber in the optically disturbed spiral galaxy IC 1859. The identification of the perturber is consistent with the comparison with numerical simulations of sloshing. The GMRT observation at 325 MHz shows faint, extended radio emission contained within the inner cold front, as seen in some galaxy clusters hosting diffuse radio mini-halos. However, unlike mini-halos, no particle reacceleration is needed to explain the extended radio emission, which is consistent with aged radio plasma redistributed by the sloshing. There is a strong analogy between the X-ray and optical phenomenology of the IC 1860 group and that of two other groups, NGC 5044 and NGC 5846, showing cold fronts. The evidence presented in this paper is among the strongest supporting the currently favored model of cold-front formation in relaxed objects and establishes the group scale as a chief environment for studying this phenomenon.

  6. Cataloguing Severe Winter Cold Snaps in the Eastern and Midwestern United States for Medium-Range Predictability

    NASA Astrophysics Data System (ADS)

    Guirguis, K.; Gershunov, A.; Bennett, S.

    2009-12-01

    Severe winter weather can be extremely disruptive to daily life and the economy. Accurate forecasts of cold outbreaks are crucial for health and safety, as well as for emergency planning by governments and the transportation and energy sectors. Short-range winter storm warnings have become much more accurate in recent years, however forecasts in the medium-range on the order of two-weeks to a month remain a challenge. To improve probabilistic forecasts, in both accuracy and lead-time, a historical catalog is prepared to describe the evolution of each winter cold outbreak from 1948, including relevant weather-climate connections. A severe cold index (SCI) for the eastern/Midwestern U.S. is constructed for the 1948/49-2008/09 winter periods, where the SCI is a local daily measure of threshold exceedance, taken as the 5th percentile of daily temperatures. The duration and spatial extent of cold spells are also explicitly considered and an “event set” of discrete cold outbreaks is designed based on the historic data. Principal components analysis is applied to surface and atmospheric observations (NCEP Reanalysis and other sources) to identify the predominant weather regimes in each season, and the evolution of these regimes. The SCI is then evaluated to identify consistent precursors. Relationships with relevant climate modes such as ENSO, NAO, PDO, MJO, etc. are used together with the annually-isolated weather regimes to develop statistical models and qualitative rules-of-thumb for use in medium-range to seasonal forecasts. The products are currently designed as a tool for operational meteorologists in forecasting energy demand, but could be functional for other end-users.

  7. Runoff and nutrient losses during winter periods in cold climates--requirements to nutrient simulation models.

    PubMed

    Deelstra, Johannes; Kvaernø, Sigrun H; Granlund, Kirsti; Sileika, Antanas Sigitas; Gaigalis, Kazimieras; Kyllmar, Katarina; Vagstad, Nils

    2009-03-01

    Large areas in Europe may experience frozen soils during winter periods which pose special challenges to modelling. Extensive data are collected in small agricultural catchments in Nordic and Baltic countries. An analysis on measurements, carried out in four small agricultural catchments has shown that a considerable amount of the yearly nutrient loss occurs during the freezing period. A freezing period was defined as the time period indicated by the maximum and minimum points on the cumulative degree-day curve. On average 6-32% of the yearly runoff was generated during this period while N-loss varied from 5-35% and P loss varied from 3-33%. The results indicate that infiltration into frozen soils might occur during the freezing period and that the runoff generating processes, at least during a considerable part of the freezing period, are rather similar compared to the processes outside the freezing period. Freeze-thaw cycles affect the infiltration capacity and aggregate stability, thereby the erosion and nutrient losses. The Norwegian catchment had a high P loss during the freezing period compared to the other catchments, most likely caused by catchment characteristics such as slope, soil types, tillage methods and fertiliser application. It is proposed to use data, collected on small agricultural dominated catchments, in the calibration and validation of watershed management models and to take into account runoff and nutrient loss processes which are representative for cold climates, thereby obtaining reliable results. PMID:19280038

  8. Link between anomalously cold winters in Russia and sea-ice decline in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Semenov, V. A.

    2016-05-01

    There were several anomalously cold winter weather regimes in Russia in the early 21st century. These regimes were usually associated with a blocking anticyclone south of the Barents Sea. Numerical simulations with an atmospheric general circulation model (AGCM) using prescribed sea-ice concentration (SIC) data for different periods during the last 50 years showed that a rapid sea-ice area decline in the Barents Sea in the last decade could bring about the formation of such a blocking anticyclone and cooling over northern Eurasia. The SIC reduction in the former period, from the second half of the 1960s to the first half of the 1990s, results in a weaker response of opposite sign. This suggests a nonlinear atmospheric circulation response to the SIC reduction in the Barents Sea, which has been previously found in the idealized AGCM simulations. An impact of the Barents Sea SIC reduction on the North Atlantic Oscillation (NAO), in particular, on the formation of the anomalously low NAO index, is found. The results indicate an important role that the Barents Sea, a region with the largest variability of the ocean-atmosphere heat exchange in the Arctic in wintertime, plays in generating anomalous weather regimes in Russia.

  9. Storms or cold fronts: what is really responsible for the extreme waves regime in the Colombian Caribbean coastal region?

    NASA Astrophysics Data System (ADS)

    Otero, L. J.; Ortiz-Royero, J. C.; Ruiz-Merchan, J. K.; Higgins, A. E.; Henriquez, S. A.

    2016-02-01

    The aim of this study is to determine the contribution and importance of cold fronts and storms to extreme waves in different areas of the Colombian Caribbean in an attempt to determine the extent of the threat posed by the flood processes to which these coastal populations are exposed. Furthermore, the study wishes to establish the actions to which coastal engineering constructions should be subject. In the calculation of maritime constructions, the most important parameter is the height of the wave. For this reason, it is necessary to establish the design wave height to which a coastal engineering structure should be resistant. This wave height varies according to the return period considered. The significant height values for the areas focused on in the study were calculated in accordance with Gumbel's extreme value methodology. The methodology was evaluated using data from the reanalysis of the spectral National Oceanic and Atmospheric Administration (NOAA) WAVEWATCH III® (WW3) model for 15 points along the 1600 km of the Colombian Caribbean coastline (continental and insular) between the years 1979 and 2009. The results demonstrated that the extreme waves caused by tropical cyclones and those caused by cold fronts have different effects along the Colombian Caribbean coast. Storms and hurricanes are of greater importance in the Guajira Peninsula (Alta Guajira). In the central area (consisting of Baja Guajira, and the cities of Santa Marta, Barranquilla, and Cartagena), the strong impact of cold fronts on extreme waves is evident. However, in the southern region of the Colombian Caribbean coast (ranging from the Gulf of Morrosquillo to the Gulf of Urabá), the extreme values of wave heights are lower than in the previously mentioned regions, despite being dominated mainly by the passage of cold fronts. Extreme waves in the San Andrés and Providencia insular region present a different dynamic from

  10. Effects of cold acclimation on sugar metabolism and sugar-related gene expression in tea plant during the winter season.

    PubMed

    Yue, Chuan; Cao, Hong-Li; Wang, Lu; Zhou, Yan-Hua; Huang, Yu-Ting; Hao, Xin-Yuan; Wang, Yu-Chun; Wang, Bo; Yang, Ya-Jun; Wang, Xin-Chao

    2015-08-01

    Sugar plays an essential role in plant cold acclimation (CA), but the interaction between CA and sugar remains unclear in tea plants. In this study, during the whole winter season, we investigated the variations of sugar contents and the expression of a large number of sugar-related genes in tea leaves. Results indicated that cold tolerance of tea plant was improved with the development of CA during early winter season. At this stage, starch was dramatically degraded, whereas the content of total sugars and several specific sugars including sucrose, glucose and fructose were constantly elevated. Beyond the CA stage, the content of starch was maintained at a low level during winter hardiness (WH) period and then was elevated during de-acclimation (DC) period. Conversely, the content of sugar reached a peak at WH stage followed by a decrease during DC stage. Moreover, gene expression results showed that, during CA period, sugar metabolism-related genes exhibited different expression pattern, in which beta-amylase gene (CsBAM), invertase gene (CsINV5) and raffinose synthase gene (CsRS2) engaged in starch, sucrose and raffinose metabolism respectively were solidly up-regulated; the expressions of sugar transporters were stimulated in general except the down-regulations of CsSWEET2, 3, 16, CsERD6.7 and CsINT2; interestingly, the sugar-signaling related CsHXK3 and CsHXK2 had opposite expression patterns at the early stage of CA. These provided comprehensive insight into the effects of CA on carbohydrates indicating that sugar accumulation contributes to tea plant cold tolerance during winter season, and a simply model of sugar regulation in response to cold stimuli is proposed. PMID:26216393

  11. Study of a Winter Monsoon Front and a Squall Line over the South China Sea by Synergetic Use of Synthetic Aperture and Weather Radar Data

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Cheng, Choming; Chan, Pakwai; Wong, Waikin; Dagestad, Knut-Frode

    2013-01-01

    Synthetic aperture radar (SAR) images acquired by the Advanced Synthetic Aperture Radar (ASAR) onboard the European Envisat satellite and weather radar images of the Hong Kong Observatory (HKO) are used to study a winter monsoon front and a squall line over the South China Sea (SCS). The atmospheric front was generated by a freshening of the northeast monsoon caused by the merging of two high pressure areas over the Chinese Continent. The high-resolution SAR image reveals finescale structures of the front which cannot be obtained by other spaceborne sensors. This front is further investigated by using other satellite data and by comparing the observational data with model data. Squall lines are lines of organized convective rain cells accompanied by wind shear and high wind gusts. It is shown that the synergetic use of high-resolution SAR and weather radar data provides a comprehensive view of the three-dimensional wind flow associated with the squall line.

  12. Numerical Simulations of the Rapid Cyclogenesis Over Canada and Evolution of a Cold Front Observed on 25 -26 April 1979

    NASA Astrophysics Data System (ADS)

    Juang, Hann-Ming Henry

    1988-12-01

    The rapid development of a cyclone over Canada and a cold front over the United States were the major weather systems observed on 25-26 April 1979 during the period of SESAME-AVE (Severe Environment Storm and Mesoscale Experiment-Atmospheric Variability Experiment) III. The objectives of this study are two-fold; one is to investigate the mechanisms of this rapid cyclogenesis, the other is to discuss the synoptic- and meso-scale environment with the cold front. A regional scale prediction model, which is the quasi-Lagrangian nested model developed by Mathur (1983) and modified in this study, was used to achieve these objectives. FGGE (First GARP (Global Atmosphere Research Program) Global Experiment) level IIIb and IIb data were used as input and verification data for numerical simulations, and for a diagnostic study. There were two cyclones involved in the event over Canada (designated as cyclones A and B). Cyclone A was given rise as a shallow surface pressure low. As the incipient cyclone A was moving southeastward, a region of high potential vorticity in the upper- and mid-troposphere, representing the tropopause folding, closed in. As a result, horizontal advection of absolute vorticity as well as differential temperature advection increased over the center of cyclone A, making cyclone A more intense and deep in its vertical extent. On the other hand, cyclone B was born shallow and remained shallow until it merged with cyclone A. Before merging, it propagated northeastward within a zone of small Richardson number. Further, relative vorticity associated with it had its maximum at the level just above the planetary boundary layer. It is concluded that cyclone B was intensified by localized baroclinic instability. The evolution of these cyclones were well simulated even with a dry model, suggesting that condensation heating was not crucial for their development. The evolution of environments associated with the cold front was well predicted by the model in

  13. Evolution of cold-tolerant fungal symbionts permits winter fungiculture by leafcutter ants at the northern frontier of a tropical ant–fungus symbiosis

    PubMed Central

    Mueller, Ulrich G.; Mikheyev, Alexander S.; Hong, Eunki; Sen, Ruchira; Warren, Dan L.; Solomon, Scott E.; Ishak, Heather D.; Cooper, Mike; Miller, Jessica L.; Shaffer, Kimberly A.; Juenger, Thomas E.

    2011-01-01

    The obligate mutualism between leafcutter ants and their Attamyces fungi originated 8 to 12 million years ago in the tropics, but extends today also into temperate regions in South and North America. The northernmost leafcutter ant Atta texana sustains fungiculture during winter temperatures that would harm the cold-sensitive Attamyces cultivars of tropical leafcutter ants. Cold-tolerance of Attamyces cultivars increases with winter harshness along a south-to-north temperature gradient across the range of A. texana, indicating selection for cold-tolerant Attamyces variants along the temperature cline. Ecological niche modeling corroborates winter temperature as a key range-limiting factor impeding northward expansion of A. texana. The northernmost A. texana populations are able to sustain fungiculture throughout winter because of their cold-adapted fungi and because of seasonal, vertical garden relocation (maintaining gardens deep in the ground in winter to protect them from extreme cold, then moving gardens to warmer, shallow depths in spring). Although the origin of leafcutter fungiculture was an evolutionary breakthrough that revolutionized the food niche of tropical fungus-growing ants, the original adaptations of this host-microbe symbiosis to tropical temperatures and the dependence on cold-sensitive fungal symbionts eventually constrained expansion into temperate habitats. Evolution of cold-tolerant fungi within the symbiosis relaxed constraints on winter fungiculture at the northern frontier of the leafcutter ant distribution, thereby expanding the ecological niche of an obligate host–microbe symbiosis. PMID:21368106

  14. Evolution of cold-tolerant fungal symbionts permits winter fungiculture by leafcutter ants at the northern frontier of a tropical ant-fungus symbiosis.

    PubMed

    Mueller, Ulrich G; Mikheyev, Alexander S; Hong, Eunki; Sen, Ruchira; Warren, Dan L; Solomon, Scott E; Ishak, Heather D; Cooper, Mike; Miller, Jessica L; Shaffer, Kimberly A; Juenger, Thomas E

    2011-03-01

    The obligate mutualism between leafcutter ants and their Attamyces fungi originated 8 to 12 million years ago in the tropics, but extends today also into temperate regions in South and North America. The northernmost leafcutter ant Atta texana sustains fungiculture during winter temperatures that would harm the cold-sensitive Attamyces cultivars of tropical leafcutter ants. Cold-tolerance of Attamyces cultivars increases with winter harshness along a south-to-north temperature gradient across the range of A. texana, indicating selection for cold-tolerant Attamyces variants along the temperature cline. Ecological niche modeling corroborates winter temperature as a key range-limiting factor impeding northward expansion of A. texana. The northernmost A. texana populations are able to sustain fungiculture throughout winter because of their cold-adapted fungi and because of seasonal, vertical garden relocation (maintaining gardens deep in the ground in winter to protect them from extreme cold, then moving gardens to warmer, shallow depths in spring). Although the origin of leafcutter fungiculture was an evolutionary breakthrough that revolutionized the food niche of tropical fungus-growing ants, the original adaptations of this host-microbe symbiosis to tropical temperatures and the dependence on cold-sensitive fungal symbionts eventually constrained expansion into temperate habitats. Evolution of cold-tolerant fungi within the symbiosis relaxed constraints on winter fungiculture at the northern frontier of the leafcutter ant distribution, thereby expanding the ecological niche of an obligate host-microbe symbiosis. PMID:21368106

  15. Creation and tidal advection of a cold salinity front in Storfjorden: 2. Supercooling induced by turbulent mixing of cold water

    NASA Astrophysics Data System (ADS)

    McPhee, Miles G.; Skogseth, Ragnheid; Nilsen, Frank; Smedsrud, Lars H.

    2013-08-01

    Measurements near the edge of fast ice in Freemansundet, Svalbard, reveal mixing processes associated with tidal advection of a sharp front in salinity, including possible supercooling induced by double diffusion in a fully turbulent water column. The front translated back and forth with the semidiurnal tide between an area of mobile (drifting) ice in Storfjorden proper, and the narrow sound covered by fast ice. Water on each side of the front was near its salinity-determined freezing temperature. Instruments deployed about 400 m into the sound from the fast ice edge measured current, temperature, conductivity, and turbulence quantities through several tidal cycles. Turbulence data illustrate that as the steep horizontal salinity (density) gradient advected past the measurement site, vertical shear near the fast-ice base induced marked flood/ebb asymmetry in turbulent mixing. As fresher water entered the sound on the flood phase, inward transport of denser water near the upper boundary was retarded, leading to statically unstable conditions and enhanced turbulence. The opposite occurred during ebb tide, as denser water underran lighter. Transient episodes of supercooling accompanied frontal passage on both flood and ebb phases. The most likely explanation for a zone of supercooled water within the strongly mixed frontal region is that during mixing of fresher, slightly warmer (but still at freezing) water from outside with saltier, colder water in the sound, the former constituent lost heat faster than gaining salt. This interpretation (differing turbulent diffusivities for heat and salt) challenges strict application of Reynolds analogy for highly turbulent shear flow.

  16. 'Only old ladies would do that': age stigma and older people's strategies for dealing with winter cold.

    PubMed

    Day, Rosie; Hitchings, Russell

    2011-07-01

    Concerns over the welfare of older people in winter have led to interventions and advice campaigns meant to improve their ability to keep warm, but older people themselves are not always willing to follow these recommendations. In this paper we draw on an in-depth study that followed twenty one older person households in the UK over a cold winter and examined various aspects of their routine warmth-related practices at home and the rationales underpinning them. We find that although certain aspects of ageing did lead participants to feel they had changing warmth needs, their practices were also shaped by the problematic task of negotiating identities in the context of a wider stigmatisation of older age and an evident resistance to ageist discourses. After outlining the various ways in which this was manifest in our study, we conclude by drawing out the implications for future policy and research. PMID:21606000

  17. Extreme temperature contrast of the year 2012 in Greece: An exceptionally cold winter and a record breaking summer

    NASA Astrophysics Data System (ADS)

    Tolika, Konstantia; Anagnostopoulou, Christina; Maheras, Panagiotis; Velikou, Kondylia

    2013-04-01

    During the past decade several regions all over Europe have experienced severe heat waves with serious social and environmental impacts. The year of 2003 was characterized by record breaking high temperatures for central Europe, while the year of 2007 was a remarkably warm year of the majority of the Eastern Mediterranean. During this year, three major heat waves were detected in Greece during summer and abnormally high temperatures were also observed through the cold season of 2007. It was found that the winter minimum temperatures were statistically more extreme than the summer maxima. Moreover, exceptionally high maximum and minimum temperatures occurred in November of 2010 affection the entire Greek region while September of the following year was also characterized by large departures of maximum temperatures from the long term mean values and the highest minimum temperature average in comparison to the reference period 1958-2000. The past year (2012) could also be characterized as a year of extremes. This time a temperature contrast was detected in the domain of study with a prolonged cold - season spell during winter and new record - breaking extreme maximum and minimum summer temperatures. More specifically it was found that the summer of 2012 was the warmest one since 1958. The whole season was characterized by long - lasting warm conditions with large departures from the long term (up to 4oC for Tmax) and this warming phenomenon was more intense during July and August. In contrast the winter season (December 2011 - February 2012) was found to be in the ten coldest winters of the last 55 years. The departures from the mean are lower than summer (1oC to 1.5oC negative anomalies) but most of the days were found to have lower Tmax, Tmin and Tmean values than the average daily temperatures of the period 1958-2000. Finally, it is worth mentioning that the year of 2012 was characterized by the highest annual temperature range reaching up to 26oC in several

  18. Correlation between Cold- and Drought-Induced Frost Hardiness in Winter Wheat and Rye Varieties 1

    PubMed Central

    Cloutier, Yves; Siminovitch, David

    1982-01-01

    Exposure of six wheat (Triticum aestivum L.) and one rye (Secale cereale L.) cultivar to 40% relative humidity for 24 hours induced the same degree of freezing tolerance in seedling epicotyls as did cold conditioning for 4 weeks at 2°C. Frost hardiness varietal relationships were the same in desiccation-stressed and cold-hardened seedlings. Drought stress could, therefore, be used as a rapid and simple method for inducing frost hardiness in seedling shoots in replacement of cold conditioning. Images PMID:16662170

  19. Use of ``Cold Spell'' indices to quantify excess chronic obstructive pulmonary disease (COPD) morbidity during winter (November to March 2000-2007): case study in Porto

    NASA Astrophysics Data System (ADS)

    Monteiro, Ana; Carvalho, Vânia; Góis, Joaquim; Sousa, Carlos

    2013-11-01

    The aim of this study was to examine the relationship between the occurrence of cold episodes and excess hospital admissions for chronic obstructive pulmonary disease (COPD) in Porto, Portugal, in order to further understand the effects of cold weather on health in milder climates. Excess COPD winter morbidity was calculated from admissions for November to March (2000-2007) in the Greater Porto Metropolitan Area (GPMA). Cold spells were identified using several indices (Díaz, World Meteorological Organization, Cold Spell Duration Index, Australian Index and Ondas’ Project Index) for the same period. Excess admissions in the periods before and after the occurrence of cold spells were calculated and related to the cold spells identified. The COPD seasonal variation admission coefficient (CVSA) showed excess winter admissions of 59 %, relative to other months. The effect of cold spell on the aggravation of COPD occurs with a lag of at least 2 weeks and differs according to the index used. This study indicates the important role of the persistence of cold periods of at least 2 weeks duration in the increase in COPD admissions. The persistence of moderate temperatures (Tmin ≤5 °C) for a week can be more significant for increasing COPD admissions than very low temperatures (Tmin ≤ 1.6 °C) for just a few days. The Ondas projects’ index provides the most accurate detection of the negative impacts of cold persistency on health, while the Diaz index is better at evaluating the consequences of short extreme cold events.

  20. Lower Stratospheric Temperature Differences Between Meteorological Analyses in two cold Arctic Winters and their Impact on Polar Processing Studies

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Sabutis, Joseph L.; Pawson, Steven; Santee, Michelle L.; Naujokat, Barbara; Swinbank, Richard; Gelman, Melvyn E.; Ebisuzaki, Wesley; Atlas, Robert (Technical Monitor)

    2001-01-01

    A quantitative intercomparison of six meteorological analyses is presented for the cold 1999-2000 and 1995-1996 Arctic winters. The impacts of using different analyzed temperatures in calculations of polar stratospheric cloud (PSC) formation potential, and of different winds in idealized trajectory-based temperature histories, are substantial. The area with temperatures below a PSC formation threshold commonly varies by approximately 25% among the analyses, with differences of over 50% at some times/locations. Freie University at Berlin analyses are often colder than others at T is less than or approximately 205 K. Biases between analyses vary from year to year; in January 2000. U.K. Met Office analyses were coldest and National Centers for Environmental Prediction (NCEP) analyses warmest. while NCEP analyses were usually coldest in 1995-1996 and Met Office or NCEP[National Center for Atmospheric Research Reanalysis (REAN) warmest. European Centre for Medium Range Weather Forecasting (ECMWF) temperatures agreed better with other analyses in 1999-2000, after improvements in the assimilation model. than in 1995-1996. Case-studies of temperature histories show substantial differences using Met Office, NCEP, REAN and NASA Data Assimilation Office (DAO) analyses. In January 2000 (when a large cold region was centered in the polar vortex), qualitatively similar results were obtained for all analyses. However, in February 2000 (a much warmer period) and in January and February 1996 (comparably cold to January 2000 but with large cold regions near the polar vortex edge), distributions of "potential PSC lifetimes" and total time spent below a PSC formation threshold varied significantly among the analyses. Largest peaks in "PSC lifetime" distributions in January 2000 were at 4-6 and 11-14 days. while in the 1996 periods, they were at 1-3 days. Thus different meteorological conditions in comparably cold winters had a large impact on expectations for PSC formation and on the

  1. IRREGULAR SLOSHING COLD FRONTS IN THE NEARBY MERGING GROUPS NGC 7618 AND UGC 12491: EVIDENCE FOR KELVIN-HELMHOLTZ INSTABILITIES

    SciTech Connect

    Roediger, E.; Kraft, R. P.; Machacek, M. E.; Forman, W. R.; Nulsen, P. E. J.; Jones, C.; Murray, S. S.

    2012-08-01

    We present results from two {approx}30 ks Chandra observations of the hot atmospheres of the merging galaxy groups centered around NGC 7618 and UGC 12491. Our images show the presence of arc-like sloshing cold fronts (CFs) wrapped around each group center and {approx}100 kpc long spiral tails in both groups. Most interestingly, the CFs are highly distorted in both groups, exhibiting 'wings' along the fronts. These features resemble the structures predicted from non-viscous hydrodynamic simulations of gas sloshing, where Kelvin-Helmholtz instabilities (KHIs) distort the CFs. This is in contrast to the structure seen in many other sloshing and merger CFs, which are smooth and featureless at the current observational resolution. Both magnetic fields and viscosity have been invoked to explain the absence of KHIs in these smooth CFs, but the NGC 7618/UGC 12491 pair are two in a growing number of both sloshing and merger CFs that appear distorted. Magnetic fields and/or viscosity may be able to suppress the growth of KHIs at the CFs in some clusters and groups, but clearly not in all. We propose that the presence or absence of KHI distortions in CFs can be used as a measure of the effective viscosity and/or magnetic field strengths in the intracluster medium.

  2. On the home front: The cold war legacy of the Hanford nuclear site

    SciTech Connect

    Stenehjem Gerber, M.

    1992-01-01

    The Hanford plutonium factory in Washington State is among the oldest and largest relics of the Cold War and is also among the dirtiest. In this book, the author states that the release of radiaoactive and toxic waste without public knowledge poses fundamental questions about American democracy. No conclusive answers to the problems at Hanford are presented, although the important questions are addressed. The reviewer feels the book may be of use as a reference catalog, within its context as a piece essentially concerned with public relations.

  3. The Colocation, or Lack Thereof, of Deep Convection and Cold Tropopause Temperatures in the Tropical Winter Western Pacific

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Recent work has suggested that dehydration near the tropical tropopause during the northern hemisphere winter is separate in place and time from the actual transfer of mass from the troposphere to the stratosphere. In fact, some work suggests that dehydration takes place in an environment where the motion is downward, with such downward motion induced either by radiative cooling over cold cloud tops or turbulent heat flux divergence due to convection. Radiative heating and cooling rates at the tropical tropopause are quite small and very sensitive to the temperature profile and underlying cloudiness. Given this, the idea of downward motion in the region of coldest temperatures and dehydration implies that coldest temperatures and underlying cloudiness are colocated. This may not necessarily be the case. This paper attempts to explore, on a preliminary basis: (1) The sensitivity of radiative heating rates at the tropical tropopause to details of the temperature profile and underlying cloudiness and (2) the relative positions of high cold clouds and cold tropopause temperatures.

  4. In Vitro Evaluation Mimics Influences of Winter Cold Water Ingestion on Ruminal Function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ingestion of cold feed and water may suddenly reduce ruminal temperature, which could result in decreased microbial activity and diet digestibility. The objective of this study was to investigate the association between critical rumen in vitro incubation temperature and activity of ruminal microorga...

  5. Effect of Phosphorus, Potassium, and Chloride Nutrition on Cold Tolerance of Winter Canola (Brassica napus L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A field experiment was conducted to determine whether fertility treatments improve cold hardiness of canola (Brassica napus L.). Measurements of chlorophyll fluorescence and overwinter survival of field-grown canola were used to evaluate the effect of chloride (Cl), potassium (K), and phosphorus (P)...

  6. Cold Stress

    MedlinePlus

    ... be at risk of cold stress. Extreme cold weather is a dangerous situation that can bring on ... the country. In regions relatively unaccustomed to winter weather, near freezing temperatures are considered factors for cold ...

  7. The concurrent variability of East Asian subtropical and polar-front jets and its implication for the winter climate anomaly in China

    NASA Astrophysics Data System (ADS)

    Xiao, Chuliang; Zhang, Yaocun; Lofgren, Brent M.; Nie, Yu

    2016-06-01

    The variability of East Asian upper level westerly jets in winter is studied with regard to the concurrent existence of subtropical jet (East Asian subtropical jet (EASJ)) and polar-front jet (East Asian polar-front jet (EAPJ)) using the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis. In the distribution of jet occurrence revealed in 6-hourly data, two jet branches along 30°N and 55°N, corresponding to locations of EASJ and EAPJ, respectively, are separated over the Tibetan Plateau. The leading two modes of zonal-mean zonal wind in East Asia extracted from a mass-weighted empirical orthogonal function analysis are characterized by the intensity changes and location displacements of two jets. The key regions for EASJ and EAPJ are then defined to represent variabilities of these two jets. Correlation analysis indicates that the subseasonal variation of EAPJ precedes EASJ by around 5 days, which can be interpreted as wave-mean flow interactions via synoptic-scale transient eddy activities. Based on the pentad intensity indices of two jets, the concurrent variabilities of EASJ and EAPJ are investigated with typical temperature and precipitation anomalies in China. The results suggest that by taking account of the two jets, we are able to get a more comprehensive understanding of the winter climate.

  8. Synoptic climatological study on precipitation in the Hokuriku District of Central Japan associated with the cold air outbreak in early winter (With Comparison to that in midwinter for the 1983/1984 winter)

    NASA Astrophysics Data System (ADS)

    Kato, Kuranoshin; Nishimura, Nanako; Haga, Yuichi

    2014-05-01

    In midwinter, heavy snowfall events are often brought in the Japan Sea side of the Japan Islands by the organized convective snowfall systems in the cold air outbreak situations. However, although the air temperature around the Japan Islands is still rather higher from November to early December ("early winter"), the "wintertime pressure pattern" often appears due to the considerable development of the Siberian high already in that season. Since the seasonal cycle in East Asia shows great variety with many rapid seasonal transitions influenced by the Asian monsoon system, detailed comparison of the daily precipitation climatology and the relating atmospheric processes in the cold air outbreak situations between early winter and midwinter would give us an interesting information for comprehending the overall aspects of such seasonal cycle there. Thus the present study firstly examined the daily precipitation climatology mainly at Takada, as an example for Hokuriku District, during the early to mid- winter of 1970/71 to 2009/10. Then the detailed analyses were made for the 1983/1984 winter (one of the coldest winters during that period) based on the operational meteorological data by JMA, including the ocean buoy data in the southern part of the Japan Sea for evaluating the sensible and the latent heat fluxes from the sea (referred to as SH and LH, respectively). The total precipitation at Takada in early winter was as large as in midwinter, although it was brought mainly not as snow but as rain. Such large climatological value was mainly reflected by the precipitation in the "wintertime pressure pattern" with large contribution of the days with more than 30 mm/day. Interestingly, mean daily precipitation in the "wintertime pressure pattern" in early winter was greater than in midwinter. It is noted that such features were generally found even in the latter half of the analysis period when the warmer winter years appeared more frequently than in the former half

  9. Volcanic Winter and Cold Tropical Uplands in Late Paleozoic Pangaea: A Thought Experiment

    NASA Astrophysics Data System (ADS)

    Heavens, N. G.; Soreghan, G. S.

    2014-12-01

    The Late Paleozoic Ice Age (LPIA) was the Earth's most recent icehouse climate prior to the Cenozoic. At present, it is generally accepted that the latitudinal gradient in climate conditions was similar to the present icehouse. High-latitude ice sheets occasionally advanced into the mid-latitudes and retreated once more, but the tropics were warmer or similar in climate to the tropics during the Plio-Pleistocene. Recently, this idea has been challenged by sedimentological evidence of glaciation and dry weathering in upland areas of the tropics as well as geochemical evidence for cold tropical oceans that is consistent with the sedimentological evidence. These observations challenge current qualitative and quantitative models of Late Paleozoic climate, implying tropical climate may have been up to 15 degrees Celsius colder than the present day at some point during the LPIA. Here we consider whether the disparity between evidence for equatorial cold in Pangaea and current models can be explained by explosive volcanic activity associated with events such as the Hercynian orogen or the Kennedy-Connors-Auburn Silicic Large Igneous Province. We find that the necessary radiative forcing for glaciation in low-latitude upland areas could be generated by explosive volcanic activity one to two orders of magnitude greater than the present day, perturbing a baseline climate with mid-latitude glaciation in both hemispheres. Such a forcing would have potentially significant impacts on the carbon cycle and ice sheet dynamics, but these effects are not likely to be unambiguously detectable in the record. Instead, we argue that measurements of mass independent fractionation of S in lacustrine sediments or other deposits sampling meteoric water would be the least ambiguous test of a hypothetical volcanic driver for late Paleozoic cold. This work was supported in part by the National Science Foundation, EAR-1337463.

  10. Large-scale evaluation of pea (Pisum sativum L.) germplasm for cold tolerance in the open field during winter in Qingdao.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a cool season crop, pea (Pisum sativum L.) can tolerate frost at the vegetative stage but has yield loss when freezing stress occurs at reproductive stage. Cold tolerance improvement of pea varieties is important for the stable yield and the expansion of winter pea planting area. Under the natura...

  11. European cold winter 2009-2010: How unusual in the instrumental record and how reproducible in the ARPEGE-Climat model?

    NASA Astrophysics Data System (ADS)

    Ouzeau, G.; Cattiaux, J.; Douville, H.; Ribes, A.; Saint-Martin, D.

    2011-06-01

    Boreal winter 2009-2010 made headlines for cold anomalies in many countries of the northern mid-latitudes. Northern Europe was severely hit by this harsh winter in line with a record persistence of the negative phase of the North Atlantic Oscillation (NAO). In the present study, we first provide a wider perspective on how unusual this winter was by using the recent 20th Century Reanalysis. A weather regime analysis shows that the frequency of the negative NAO was unprecedented since winter 1939-1940, which is then used as a dynamical analog of winter 2009-2010 to demonstrate that the latter might have been much colder without the background global warming observed during the twentieth century. We then use an original nudging technique in ensembles of global atmospheric simulations driven by observed sea surface temperature (SST) and radiative forcings to highlight the relevance of the stratosphere for understanding if not predicting such anomalous winter seasons. Our results demonstrate that an improved representation of the lower stratosphere is necessary to reproduce not only the seasonal mean negative NAO signal, but also its intraseasonal distribution and the corresponding increased probability of cold waves over northern Europe.

  12. Use of "Cold Spell" indices to quantify excess chronic obstructive pulmonary disease (COPD) morbidity during winter (November to March 2000-2007): case study in Porto.

    PubMed

    Monteiro, Ana; Carvalho, Vânia; Góis, Joaquim; Sousa, Carlos

    2013-11-01

    The aim of this study was to examine the relationship between the occurrence of cold episodes and excess hospital admissions for chronic obstructive pulmonary disease (COPD) in Porto, Portugal, in order to further understand the effects of cold weather on health in milder climates. Excess COPD winter morbidity was calculated from admissions for November to March (2000-2007) in the Greater Porto Metropolitan Area (GPMA). Cold spells were identified using several indices (Díaz, World Meteorological Organization, Cold Spell Duration Index, Australian Index and Ondas' Project Index) for the same period. Excess admissions in the periods before and after the occurrence of cold spells were calculated and related to the cold spells identified. The COPD seasonal variation admission coefficient (CVSA) showed excess winter admissions of 59 %, relative to other months. The effect of cold spell on the aggravation of COPD occurs with a lag of at least 2 weeks and differs according to the index used. This study indicates the important role of the persistence of cold periods of at least 2 weeks duration in the increase in COPD admissions. The persistence of moderate temperatures (Tmin ≤5 °C) for a week can be more significant for increasing COPD admissions than very low temperatures (Tmin ≤ 1.6 °C) for just a few days. The Ondas projects' index provides the most accurate detection of the negative impacts of cold persistency on health, while the Diaz index is better at evaluating the consequences of short extreme cold events. PMID:23274835

  13. Evaluating the role of fronts in habitat overlaps between cold and warm water species in the western North Pacific: A proof of concept

    NASA Astrophysics Data System (ADS)

    Mugo, Robinson M.; Saitoh, Sei-Ichi; Takahashi, Fumihiro; Nihira, Akira; Kuroyama, Tadaaki

    2014-09-01

    Cold- and warm-water species' fishing grounds show a spatial synchrony around fronts in the western North Pacific (WNP). However, it is not yet clear whether a front (thermal, salinity or chlorophyll) acts as an absolute barrier to fish migration on either side or its structure allows interaction of species with different physiological requirements. Our objective was to assess potential areas of overlap between cold- and warm-water species using probabilities of presence derived from fishery datasets and remotely sensed environment data in the Kuroshio-Oyashio region in the WNP. Fishery data comprised skipjack tuna (Katsuwonus pelamis) fishing locations and proxy presences (derived from fishing night light images) for neon flying squid (Ommastrephes bartrami) and Pacific saury (Cololabis saira). Monthly (August-November) satellite remotely sensed sea-surface temperature, chlorophyll-a and sea-surface height anomaly images were used as environment data. Maximum entropy (MaxEnt) models were used to determine probabilities of presence (PoP) for each set of fishery and environment data for the area 35-45°N and 140-160°E. Maps of both sets of PoPs were compared and areas of overlap identified using a combined probability map. Results indicated that areas of spatial overlap existed among the species habitats, which gradually widened from September to November. The reasons for these overlaps include the presence of strong thermal/ocean-color gradients between cold Oyashio and warm Kuroshio waters, and also the presence of the sub-arctic front. Due to the high abundance of food along frontal zones, the species use the fronts as foraging grounds while confining within physiologically tolerable waters on either side of the front. The interaction zone around the front points to areas that might be accessible to both species for foraging, which suggests intense prey-predator interaction zones.

  14. Pretreatment of landfill leachate using deep shaft aeration bioreactor (DSAB) in cold winter season.

    PubMed

    Niu, Jing; Zhang, Tongju; He, Yijia; Zhou, Haiyan; Zhao, Aihua; Zhao, Youcai

    2013-05-15

    A pilot-scale deep shaft aeration bioreactor (DSAB) with 110 m in depth and 0.5m in diameter for the pretreatment of landfill leachate in winter was operated at a daily treatment scale of around 10-20 tons. It was found that the performance of the DSAB mainly depended on the inflow loads and concentrations of pollutants. NH3-N, TN, COD, TOC removals of 66-94%, 41-64%, 67-87%, 55-92% at organic load rate of 1.7-9.4 g CODL(-1)day(-1) and hydraulic retention time of 1-2d were obtained using DSAB, respectively, with the lowest ambient temperature of -3 °C. The effluent COD can be reduced to below 1000 mg/L, an acceptable level for advanced treatment using reverse osmosis system, when the influent COD was below 7000 mg/L at 10t/d. The EEM and GPC analysis implied that the non-biodegradable contaminants such as humic- and fulvic-like DOM dominated in the organic fractions of the effluent, which rendered the biological treatment ineffective. Compared with 20-40% removals obtained using traditional biological processes below 15 °C, DSAB showed a higher treatment efficiency for COD and NH3-N, even though at adverse conditions of poor carbon source, lower C/N ratio and high nitrite concentrations in the leachate of test. PMID:23542320

  15. Coping with the cold: an ecological context for the abundance and distribution of rock sandpipers during winter in upper Cook Inlet, Alaska

    USGS Publications Warehouse

    Ruthrauff, Daniel R.; Gill, Robert E., Jr.; Tibbitts, T. Lee

    2013-01-01

    Shorebirds are conspicuous and abundant at high northern latitudes during spring and summer, but as seasonal conditions deteriorate, few remain during winter. To the best of our knowledge, Cook Inlet, Alaska (60.6˚ N, 151.6˚ W), is the world’s coldest site that regularly supports wintering populations of shorebirds, and it is also the most northerly nonbreeding location for shorebirds in the Pacific Basin. During the winters of 1997–2012, we conducted aerial surveys of upper Cook Inlet to document the spatial and temporal distribution and number of Rock Sandpipers (Calidris ptilocnemis) using the inlet. The average survey total was 8191 ± 6143 SD birds, and the average of each winter season’s highest single-day count was 13 603 ± 4948 SD birds. We detected only Rock Sandpipers during our surveys, essentially all of which were individuals of the nominate subspecies (C. p. ptilocnemis). Survey totals in some winters closely matched the population estimate for this subspecies, demonstrating the region’s importance as a nonbreeding resource to the subspecies. Birds were most often found at only a handful of sites in upper Cook Inlet, but shifted their distribution to more southerly locations in the inlet during periods of extreme cold. Two environmental factors allow Rock Sandpipers to inhabit Cook Inlet during winter: 1) an abundant bivalve (Macoma balthica) food source and 2) current and tidal dynamics that keep foraging substrates accessible during all but extreme periods of cold and ice accretion. C. p. ptilocnemis is a subspecies of high conservation concern for which annual winter surveys may serve as a relatively inexpensive population-monitoring tool that will also provide insight into adaptations that allow these birds to exploit high-latitude environments in winter.

  16. How much can we learn from a merging cold front cluster? Insights from X-ray temperature and radio maps of A3667

    SciTech Connect

    Datta, Abhirup; Schenck, David E.; Burns, Jack O.; Skillman, Samuel W.; Hallman, Eric J.

    2014-10-01

    The galaxy cluster A3667 is an ideal laboratory to study the plasma processes in the intracluster medium. High-resolution Chandra X-ray observations show a cold front in A3667. At radio wavelengths, A3667 reveals a double radio-relic feature in the outskirts of the cluster. These suggest multiple merger events in this cluster. In this paper, we analyze the substantial archival X-ray observations of A3667 from the Chandra X-ray Observatory and compare these with existing radio observations as well as state-of-the-art adaptive mesh refinement MHD cosmological simulations using Enzo. We have used two temperature map making techniques, weighted Voronoi tessellation and adaptive circular binning, to produce the high-resolution and largest field-of-view temperature maps of A3667. These high-fidelity temperature maps allow us to study the X-ray shocks in the cluster using a new two-dimensional shock-finding algorithm. We have also estimated the Mach numbers from the shocks inferred from previous ATCA radio observations. The combined shock statistics from the X-ray and radio data are in agreement with the shock statistics in a simulated MHD cluster. We have also studied the profiles of the thermodynamic properties across the cold front using ∼447 ks from the combined Chandra observations on A3667. Our results show that the stability of the cold front in A3667 can be attributed to the suppression of the thermal conduction across the cold front by a factor of ∼100-700 compared to the classical Spitzer value.

  17. 2012/13 abnormal cold winter in Japan associated with Large-scale Atmospheric Circulation and Local Sea Surface Temperature over the Sea of Japan

    NASA Astrophysics Data System (ADS)

    Ando, Y.; Ogi, M.; Tachibana, Y.

    2013-12-01

    On Japan, wintertime cold wave has social, economic, psychological and political impacts because of the lack of atomic power stations in the era of post Fukushima world. The colder winter is the more electricity is needed. Wintertime weather of Japan and its prediction has come under the world spotlight. The winter of 2012/13 in Japan was abnormally cold, and such a cold winter has persisted for 3 years. Wintertime climate of Japan is governed by some dominant modes of the large-scale atmospheric circulations. Yasunaka and Hanawa (2008) demonstrated that the two dominant modes - Arctic Oscillation (AO) and Western Pacific (WP) pattern - account for about 65% of the interannual variation of the wintertime mean surface air temperature of Japan. A negative AO brings about cold winter in Japan. In addition, a negative WP also brings about cold winter in Japan. Looking back to the winter of 2012/13, both the negative AO and negative WP continued from October through December. If the previous studies were correct, it would have been extremely very cold from October through December. In fact, in December, in accordance with previous studies, it was colder than normal. Contrary to the expectation, in October and November, it was, however, warmer than normal. This discrepancy signifies that an additional hidden circumstance that heats Japan overwhelms these large-scale atmospheric circulations that cool Japan. In this study, we therefore seek an additional cause of wintertime climate of Japan particularly focusing 2012 as well as the AO and WP. We found that anomalously warm oceanic temperature surrounding Japan overwhelmed influences of the AO or WP. Unlike the inland climate, the island climate can be strongly influenced by surrounding ocean temperature, suggesting that large-scale atmospheric patterns alone do not determine the climate of islands. (a) Time series of a 5-day running mean AO index (blue) as defined by Ogi et al., (2004), who called it the SVNAM index. For

  18. Gelation in protein extracts from cold acclimated and non-acclimated winter rye (Secale cereale L. cv Musketeer).

    PubMed

    Lim, Ze Long; Low, Nicholas H; Moffatt, Barbara A; Gray, Gordon R

    2013-04-01

    A protein gel is a three-dimensional network consisting of molecular interactions between biopolymers that entrap a significant volume of a continuous liquid phase (water). Molecular interactions in gels occur at junction zones within and between protein molecules through electrostatic forces, hydrogen bonding, hydrophobic associations (van der Waals attractions) and covalent bonding. Gels have the physicochemical properties of both solids and liquids, and are extremely important in the production and stability of a variety of foods, bioproducts and pharmaceuticals. In this study, gelation was induced in phenol extracted protein fractions from non-acclimated (NA) and cold-acclimated (CA) winter rye (Secale cereale L. cv Musketeer) leaf tissue after repeated freeze-thaw treatments. Gel formation only occurred at high pH (pH 12.0) and a minimum of 3-4 freeze-thaw cycles were required. The gel was thermally stable and only a specific combination of chemical treatments could disrupt the gel network. SDS-PAGE analysis identified ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) as the major protein component in the gel, although Rubisco itself did not appear to be a factor in gelation. Raman spectroscopy suggested changes in protein secondary structure during freeze-thaw cycles. Overall, the NA and CA gels were similar in composition and structure, with the exception that the CA gel appeared to be amyloidic in nature based on thioflavin T (ThT) fluorescence. Protein gelation, particularly in the apoplast, may confer protection against freeze-induced dehydration and potentially have a commercial application to improve frozen food quality. PMID:23348601

  19. Winter Weather Emergencies

    MedlinePlus

    Severe winter weather can lead to health and safety challenges. You may have to cope with Cold related health problems, including ... there are no guarantees of safety during winter weather emergencies, you can take actions to protect yourself. ...

  20. Long-term growth under elevated CO2 suppresses biotic stress genes in non-acclimated, but not cold-acclimated winter wheat.

    PubMed

    Kane, Khalil; Dahal, Keshav P; Badawi, Mohamed A; Houde, Mario; Hüner, Norman P A; Sarhan, Fathey

    2013-11-01

    This study compared the photosynthetic performance and the global gene expression of the winter hardy wheat Triticum aestivum cv Norstar grown under non-acclimated (NA) or cold-acclimated (CA) conditions at either ambient CO2 or elevated CO2. CA Norstar maintained comparable light-saturated and CO2-saturated rates of photosynthesis but lower quantum requirements for PSII and non-photochemical quenching relative to NA plants even at elevated CO2. Neither NA nor CA plants were sensitive to feedback inhibition of photosynthesis at elevated CO2. Global gene expression using microarray combined with bioinformatics analysis revealed that genes affected by elevated CO2 were three times higher in NA (1,022 genes) compared with CA (372 genes) Norstar. The most striking effect was the down-regulation of genes involved in the plant defense responses in NA Norstar. In contrast, cold acclimation reversed this down-regulation due to the cold induction of genes involved in plant pathogenesis resistance; and cellular and chloroplast protection. These results suggest that elevated CO2 has less impact on plant performance and productivity in cold-adapted winter hardy plants in the northern climates compared with warmer environments. Selection for cereal cultivars with constitutively higher expression of biotic stress defense genes may be necessary under elevated CO2 during the warm growth period and in warmer climates. PMID:23969557

  1. Effect of Severe Winter Cold on the Photosynthetic Potentials of Three Co-occurring Evergreen Woody Species in a Mediterranean Forest, Catalonia (Spain)

    NASA Astrophysics Data System (ADS)

    Sperlich, Dominik; Gracia, Carlos; Peñuelas, Josep; Sabaté, Santi

    2013-04-01

    Evergreen tree species in the Mediterranean region have to cope with a wide range of environmental stress conditions from summer drought to winter cold. The winter period can lead to photoinhibition due to a combination of high solar irradiances and chilling temperatures which can reduce the light saturation point. However, Mediterranean winter mildness can lead periodically to favourable environmental conditions above the threshold for positive carbon balance benefitting evergreen woody species in contrast to winter deciduous species. The advantage of being able to photosynthesis all year round with a significant fraction in the winter month is compensating for the lower photosynthetic potentials during spring and summer in comparison to deciduous species. In this work, we investigated the physiological behaviour of three evergreen tree species (Quercus ilex, Pinus halepensis, Arbutus undeo) co-occurring in a natural and mature Mediterranean forest after a period of mild winter conditions and their response to a sudden period of intense cold weather. Therefore, we examined in each period the photosynthetic potentials by estimating the maximum carboxylation rate (Vcmax) and the maximum electron transport rate (Jmax) through gas exchange measurements. The results indicate that all species exhibited extraordinary high photosynthetic potentials during the first period of measurement as a response to the mild conditions. However, the sudden cold period affected negatively the photosynthetic potentials of Quercus ilex and A. unedo with reduction ranging between 37 to 45 %, whereas they were observed to be only insignificantly reduced in Pinus halepensis. Our results can be explained by previous classifications into photoinhibition-avoiding (P. halpensis) and photoinhibition-tolerant (Q. ilex, A. undeo) species on the basis of their susceptibility to dynamic photoinhibition (Martinez Ferri 2000). Photoinhibition tolerant species are characterised with a more dynamic

  2. Cold-front driven storm erosion and overwash in the central part of the Isles Dernieres, a Louisiana barrier-island arc

    USGS Publications Warehouse

    Dingler, J.R.; Reiss, T.E.

    1990-01-01

    Tropical and extratropical storms produce significant erosion on the barrier islands of Louisiana. Over the past 100 years, such storms have produced at least 2 km of northward beach-face retreat and the loss of 63% of the surface area of the Isles Dernieres, a low-lying barrier-island arc along the central Louisiana coast. Elevations on the islands within the arc are typically less than 2 m above mean sea level. The islands typically have a washover-flat topography with occasional, poorly developed, dune-terrace topography consisting of low-lying and broken dunes. The central part of the arc consists of salt-marsh deposits overlain by washover sands along the Gulf of Mexico shoreline. Sand thicknesses range from zero behind the beach, to less than 2 m under the berm crest, and back to zero in the first nearshore trough. The sand veneer is sufficiently thin that storms can strip all the sand from the beach face, exposing the underlying marsh deposits. The geomorphic changes produced by cold fronts, a type of extratropical storm that commonly affect the Isles Dernieres between late fall and early spring are described. Between August 1986 and September 1987, repeated surveys along eleven shore-normal transects that covered 400 m of shoreline revealed the timing and extent of cold-front-produced beach change along a typical section of the central Isles Dernieres. During the study period, the beach face retreated approximately 20 m during the cold-front season but did not rebuild during the subsequent summer. Because the volume of sand deposited on the backshore (5600 m3) was less than the volume of material lost from the beach face (19,200 m3), approximately 13,600 m3 of material disappeared. Assuming that underlying marsh deposits decrease in volume in direct proportion to the amount of beach-face retreat, an estimate of the mud loss during the study period is 14,000 m3. Thus, the decrease in volume along the profiles can be accounted for without removing any sand

  3. Organic and inorganic aerosol compositions in Ulaanbaatar, Mongolia, during the cold winter of 2007 to 2008: Dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Tsatsral, Batmunkh; Kim, Young J.; Kawamura, Kimitaka

    2010-11-01

    To investigate the distributions and sources of water-soluble organic acids in the Mongolian atmosphere, aerosol samples (PM2.5, n = 34) were collected at an urban site (47.92°N, 106.90°E, ˜1300 m above sea level) in Ulaanbaatar, the capital of Mongolia, during the cold winter. The samples were analyzed for water-soluble dicarboxylic acids (C2-C12) and related compounds (ketocarboxylic acids and α-dicarbonyls), as well as organic carbon (OC), elemental carbon, water-soluble OC, and inorganic ions. Distributions of dicarboxylic acids and related compounds were characterized by a predominance of terephthalic acid (tPh; 130 ± 51 ng m-3, 19% of total detected organic acids) followed by oxalic (107 ± 28 ng m-3, 15%), succinic (63 ± 20 ng m-3, 9%), glyoxylic (55 ± 18 ng m-3, 8%), and phthalic (54 ± 27 ng m-3, 8%) acids. Predominance of terephthalic acid, which has not been reported previously in atmospheric aerosols, was mainly due to uncontrolled burning of plastic bottles and bags in home stoves for heating and waste incineration during the cold winter. This study demonstrated that most of the air pollutants were directly emitted from local sources such as heat and power plants, home stoves, and automobiles. Development of an inversion layer (<700 m above ground level) over the basin of Ulaanbaatar accelerated the accumulation of pollutants, causing severe haze episodes during the winter season.

  4. Plasma membrane lipid alterations associated with cold acclimation of winter rye seedlings (Secale cereale L. cv Puma)

    SciTech Connect

    Lynch, D.V.; Steponkus, P.L. )

    1987-01-01

    Highly enriched plasma membrane fractions were isolated from leaves of nonacclimated (NA) and acclimated (ACC) rye (Secale cereale L. cv Puma) seedlings. Collectively, free sterols, steryl glucosides, and acylated steryl glucosides constituted > 50 mole % of the total lipid in both NA and ACC plasma membrane fractions. Glucocerebrosides containing hydroxy fatty acids constituted the major glycolipid class of the plasma membrane, accounting for 16 mole % of the total lipid. Phospholipids, primarily phosphatidylcholine and phosphatidylethanolamine with lesser amounts of phosphatidylglycerol, phosphatidic acid, phosphatidylserine, and phosphatidylinositol, comprised only 32 mole% of the total lipid in NA samples. Following cold acclimation, free sterols increased from 33 to 44 mole %, while steryl glucosides and acylated steryl glucosides decreased from 15 to 6 mole % and 4 to 1 mole %, respectively. Sterol analyses of these lipid classes demonstrated that free {beta}-sitosterol increased from 21 to 32 mole % (accounting for the increase in free sterols as a class) at the expense of sterol derivatives containing {beta}-sitosterol. Glucocerebrosides decreased from 16 to 7 mole % of the total lipid following cold acclimation. In addition, the relative proportions of associated hydroxy fatty acids, including 22:0 (h), 24:0 (h), 22:1 (h), and 24:1 (h) were altered. The phospholipid content of the plasma membrane fraction increased to 42 mole % of the total lipid following cold acclimation. Although the relative proportions of the individual phospholipids did not change appreciably after cold acclimation, there were substantial differences in the molecular species. Di-unsaturated molecular species of phosphatidylcholine and phosphatidylethanolamine increased following acclimation. These results demonstrate that cold acclimation results in substantial changes in the lipid composition of the plasma membrane.

  5. Plasma Membrane Lipid Alterations Associated with Cold Acclimation of Winter Rye Seedlings (Secale cereale L. cv Puma) 1

    PubMed Central

    Lynch, Daniel V.; Steponkus, Peter L.

    1987-01-01

    Highly enriched plasma membrane fractions were isolated from leaves of nonacclimated (NA) and acclimated (ACC) rye (Secale cereale L. cv Puma) seedlings. Collectively, free sterols, steryl glucosides, and acylated steryl glucosides constituted >50 mole% of the total lipid in both NA and ACC plasma membrane fractions. Glucocerebrosides containing hydroxy fatty acids constituted the major glycolipid class of the plasma membrane, accounting for 16 mole% of the total lipid. Phospholipids, primarily phosphatidylcholine and phosphatidylethanolamine with lesser amounts of phosphatidylglycerol, phosphatidic acid, phosphatidylserine, and phosphatidylinositol, comprised only 32 mole% of the total lipid in NA samples. Following cold acclimation, free sterols increased from 33 to 44 mole%, while steryl glucosides and acylated steryl glucosides decreased from 15 to 6 mole% and 4 to 1 mole%, respectively. Sterol analyses of these lipid classes demonstrated that free β-sitosterol increased from 21 to 32 mole% (accounting for the increase in free sterols as a class) at the expense of sterol derivatives containing β-sitosterol. Glucocerebrosides decreased from 16 to 7 mole% of the total lipid following cold acclimation. In addition, the relative proportions of associated hydroxy fatty acids, including 22:0 (h), 24:0 (h), 22:1 (h), and 24:1 (h), were altered. The phospholipid content of the plasma membrane fraction increased to 42 mole% of the total lipid following cold acclimation. Although the relative proportions of the individual phospholipids did not change appreciably after cold acclimation, there were substantial differences in the molecular species. Di-unsaturated molecular species (18:2/18:2, 18:2/18:3, 18:3/18:3) of phosphatidylcholine and phosphatidylethanolamine increased following acclimation. These results demonstrate that cold acclimation results in substantial changes in the lipid composition of the plasma membrane. PMID:16665335

  6. Influence of the Eurasian snow on the negative North Atlantic Oscillation in subseasonal forecasts of the cold winter 2009/2010

    NASA Astrophysics Data System (ADS)

    Orsolini, Y. J.; Senan, R.; Vitart, F.; Balsamo, G.; Weisheimer, A.; Doblas-Reyes, F. J.

    2015-11-01

    The winter 2009/2010 was remarkably cold and snowy over North America and across Eurasia, from Europe to the Far East, coinciding with a pronounced negative phase of the North Atlantic Oscillation (NAO). While previous studies have investigated the origin and persistence of this anomalously negative NAO phase, we have re-assessed the role that the Eurasian snowpack could have played in contributing to its maintenance. Many observational and model studies have indicated that the autumn Eurasian snow cover influences circulation patterns over high northern latitudes. To investigate that role, we have performed a suite of forecasts with the coupled ocean-atmosphere ensemble prediction system from the European Centre for Medium-Range Weather Forecasts. Pairs of 2-month ensemble forecasts with either realistic or else randomized snow initial conditions are used to demonstrate how an anomalously thick snowpack leads to an initial cooling over the continental land masses of Eurasia and, within 2 weeks, to the anomalies that are characteristic of a negative NAO. It is also associated with enhanced vertical wave propagation into the stratosphere and deceleration of the polar night jet. The latter then exerts a downward influence into the troposphere maximizing in the North Atlantic region, which establishes itself within 2 weeks. We compare the forecasted NAO index in our simulations with those from several operational forecasts of the winter 2009/2010 made at the ECWMF, and highlight the importance of relatively high horizontal resolution.

  7. Influence of the Eurasian snow on the negative North Atlantic Oscillation in subseasonal forecasts of the cold winter 2009/2010

    NASA Astrophysics Data System (ADS)

    Orsolini, Y. J.; Senan, R.; Vitart, F.; Balsamo, G.; Weisheimer, A.; Doblas-Reyes, F. J.

    2016-08-01

    The winter 2009/2010 was remarkably cold and snowy over North America and across Eurasia, from Europe to the Far East, coinciding with a pronounced negative phase of the North Atlantic Oscillation (NAO). While previous studies have investigated the origin and persistence of this anomalously negative NAO phase, we have re-assessed the role that the Eurasian snowpack could have played in contributing to its maintenance. Many observational and model studies have indicated that the autumn Eurasian snow cover influences circulation patterns over high northern latitudes. To investigate that role, we have performed a suite of forecasts with the coupled ocean-atmosphere ensemble prediction system from the European Centre for Medium-Range Weather Forecasts. Pairs of 2-month ensemble forecasts with either realistic or else randomized snow initial conditions are used to demonstrate how an anomalously thick snowpack leads to an initial cooling over the continental land masses of Eurasia and, within 2 weeks, to the anomalies that are characteristic of a negative NAO. It is also associated with enhanced vertical wave propagation into the stratosphere and deceleration of the polar night jet. The latter then exerts a downward influence into the troposphere maximizing in the North Atlantic region, which establishes itself within 2 weeks. We compare the forecasted NAO index in our simulations with those from several operational forecasts of the winter 2009/2010 made at the ECWMF, and highlight the importance of relatively high horizontal resolution.

  8. The impact of winter 2012 cold outbreak over the Northern Adriatic Sea dynamics: preliminary comparison among data and high resolution operational atmospheric models

    NASA Astrophysics Data System (ADS)

    Davolio, Silvio; Miglietta, Mario M.; Carniel, Sandro; Benetazzo, Alvise; Buzzi, Andrea; Drofa, Oxana; Falco, Pierpaolo; Fantini, Maurizio; Malguzzi, Piero; Ricchi, Antonio; Russo, Aniello; Paccagnella, Tiziana; Sclavo, Mauro

    2013-04-01

    Shelf dense water formation (DWF) events may be taking place during winter time on the broad, shallow shelf in the northern region of the Adriatic basin exposed to the Bora winds, bringing cold, dry air from the north-east down the Dinaric Alps. Indeed, the resulting intense evaporation and cooling of the shelf waters may produce North Adriatic Dense Water (NAdDW), which then tends to sink and ''cascade'' all the way to the southern basin. During these rather episodic formation processes, more frequent during winter time, the main controlling factors are intense cold wind out- breaks, the ambient water density, preconditioned during late autumn, and also other factors, e.g. river discharges. When such processes of buoyancy extraction happen, several isopycnic surfaces outcrop and very often the whole water column (20-25 m deep) may be ventilated. However, the general process of northern water masses flowing to the southern part of the Adriatic basin is complex and far from being completely understood. In order to understand and model these processes, it is mandatory to utilize high resolution meteorological forcing fields and circulation models, at least to model particular events in Adriatic marine circulation, if not its longer term (e.g., seasonal) characteristics. The use of low resolution winds in fact necessarily implies a calibration factor to better match surface fluxes and to reproduce wind-driven circulation. This is particularly evident in the case of the cross-basin Bora pattern, because the complexity and small scale of Adriatic orography is often poorly reproduced in atmospheric models, while Bora flow is composed of an alternation of high and low wind speed 'strips' crossing the Adriatic in correspondence of the fine scale (10-100 km) Balkanic orographic gaps. Within the framework of activities of the Italian flagship Project "RITMARE" and of the FIRB "DECALOGO", we focused on the current meteorological modeling capabilities to describe an event of

  9. Gravity wave characteristics in the middle atmosphere during the CESAR campaign at Palma de Mallorca in 2011/2012: Impact of extratropical cyclones and cold fronts

    NASA Astrophysics Data System (ADS)

    Kramer, R.; Wüst, S.; Schmidt, C.; Bittner, M.

    2015-06-01

    Based on a measuring campaign which was carried out at Mallorca (39.6°N, 2.7°E) as cooperation between Agència Estatal de Meteorologia (AEMET) and Deutsches Zentrum für Luft- und Raumfahrt, engl. 'German Aerospace Center' (DLR) in 2011/2012 (September-January), 143 radiosondes (day and night) providing vertical temperature and wind profiles were released. Additionally, nocturnal mesopause temperature measurements with a temporal resolution of about 1 min were conducted by the infrared (IR) - Ground-based Infrared P-branch Spectrometer (GRIPS) during the campaign period. Strongly enhanced gravity wave activity in the lower stratosphere is observed which can be attributed to a hurricane-like storm (so-called Medicane) and to passing by cold fronts. Statistical features of gravity wave parameters including energy densitiy and momentum fluxes are calculated. Gravity wave momentum fluxes turned out being up to five times larger during severe weather. Moreover, gravity wave horizontal propagation characteristics are derived applying hodograph and Stokes parameter analysis. Preferred directions are of southeast and northwest due to prevailing wind directions at Mallorca.

  10. Impacts of a strong cold front on concentrations of HONO, HCHO, O 3, and NO 2 in the heavy traffic urban area of Beijing

    NASA Astrophysics Data System (ADS)

    An, Junling; Zhang, Wei; Qu, Yu

    Much rain and strong winds caused by a cold front occurred in Beijing during the period of Sep. 27 to Oct. 4, 2004 and led to sharp drops in maximum and mean concentrations of HONO, HCHO, O 3, and NO 2, i.e., the maximum concentrations were reduced by 5.9, 21.3, 45.6, and 44.4 ppb, respectively, and the mean concentrations were decreased by 4.0, 5.5, 30.3, and 32.3 ppb, respectively. For daily HO x production rates HONO photolysis was the largest contributor and over 90% contributions were from photolysis of HONO and HCHO. Large number and area percentages of soot aggregate from PM10, and high correlations between concentrations of PM10 and chemical formation of HONO suggested that heterogeneous reactions of NO 2 on surfaces of soot aggregate could be a key source of HONO in the heavy traffic areas of Beijing during the night and should be considered in air quality simulations for such areas.

  11. Bio-Optical Properties and Ocean Color Algorithms for Coastal Waters Influenced by the Mississippi River During a Cold Front Passage

    NASA Technical Reports Server (NTRS)

    D'Sa Eurico J.; Miller, Richard L.; DelCastillo, Carlos

    2006-01-01

    During the passage of a cold front in March 2002, bio-optical properties examined in coastal waters impacted by the Mississippi River indicated westward advective flows and increasing river discharge containing a larger nonalgal particle content contributed significantly to surface optical variability. A comparison of seasonal data from three cruises indicated spectral models of absorption and scattering to be generally consistent with other coastal environments, while their parameterization in terms of chlorophyll a concentration (Chl) showed seasonal variability. The exponential slope of the colored dissolved organic matter (CDOM) averaged 0.0161 plus or minus 0.00054 per nanometer, and for nonalgal absorption it averaged 0.011 per nanometer with deviations from general trends observed due to anomalous water properties. Although the phytoplankton specific absorption coefficients varied over a wide range (0.02 to 0.1 square meters (mg Chl) sup -1)) being higher in offshore surface waters, values of phytoplankton absorption spectra at the SeaWiFS wavebands were highly correlated to modeled values. The normalized scattering spectral shapes and the mean spectrum were in agreement to observations in other coastal waters, while the backscattering ratios were on average lower in phytoplankton dominated surface waters (0.0101 plus or minus 0.002) and higher in near-bottom waters (0.0191 plus or minus 0.0045) with low Chl. Average percent differences in remote sensing reflectance R (sub rs) derived form modeled and in-eater radiometric measurements were highest in the blue wavebands (52%) and at sampling stations with a ore stratified water column. Estimates of Chl and CDOM absorption derived from SeaWiFS images generated using regional empirical algorithms were highly correlated to in situ data.

  12. The Excess Winter Deaths Measure

    PubMed Central

    Gasparrini, Antonio

    2016-01-01

    Background: Excess winter deaths, the ratio between average daily deaths in December–March versus other months, is a measure commonly used by public health practitioners and analysts to assess health burdens associated with wintertime weather. We seek to demonstrate that this measure is fundamentally biased and can lead to misleading conclusions about health impacts associated with current and future winter climate. Methods: Time series regression analysis of 779,372 deaths from natural causes in London over 15 years (1 August 1997–31 July 2012),collapsed by day of death and linked to daily temperature values. The outcome measures were the excess winter deaths index, and daily and annual deaths attributable specifically to cold. Results: Most of the excess winter deaths are driven by cold: The excess winter deaths index decreased from 1.19 to 1.07 after excluding deaths attributable to low temperatures. Over 40% of cold-attributable deaths occurred outside of the December–March period, leading to bias in the excess winter deaths measure. Although there was no relationship between winter severity and annual excess winter deaths, there was a clear correlation with annual cold-attributable deaths. Conclusions: Excess winter deaths is not an appropriate indicator of cold-related health impacts, and its use should be discontinued. We advocate alternative measures. The findings we present bring into doubt previous claims that cold-related deaths in the UK will not reduce in future as a result of climate change. PMID:26986872

  13. Ocean-Atmosphere Environments of Antarctic-Region Cold-Air Mesocyclones: Evaluation of Reanalyses for Contrasting Adjacent 10-Day Periods ("Macro-Weather") in Winter.

    NASA Astrophysics Data System (ADS)

    Carleton, A. M.; Auger, J.; Birkel, S. D.; Maasch, K. A.; Mayewski, P. A.; Claud, C.

    2015-12-01

    Mesoscale cyclones in cold-air outbreaks (mesocyclones) feature in the weather and climate of the Antarctic (e.g., Ross Sea) and sub-antarctic (Drake Passage). They adversely impact field operations, and influence snowfall, the ice-sheet mass balance, and sea-air energy fluxes. Although individual mesocyclones are poorly represented on reanalyses, these datasets robustly depict the upper-ocean and troposphere environments in which multiple mesocyclones typically form. A spatial metric of mesocyclone activity—the Meso-Cyclogenesis Potential (MCP)—used ERA-40 anomaly fields of: sea surface temperature (SST) minus marine air temperature (MAT), near-surface winds, 500 hPa air temperature, and the sea-ice edge location. MCP maps composited by teleconnection phases for 1979-2001, broadly correspond to short-period satellite "climatologies" of mesocyclones. Here, we assess 3 reanalysis datasets (CFSR, ERA-I and MERRA) for their reliably to depict MCP patterns on weekly to sub-monthly periods marked by strong regional shifts in mesocyclone activity (frequencies, track densities) occurring during a La Niña winter: June 21-30, 1999 (SE Indian Ocean) and September 1-10, 1999 (Ross Sea sector). All reanalyses depict the marked variations in upper ocean and atmosphere variables between adjacent 10-day periods. Slight differences may owe to model resolution or internal components (land surface, coupled ocean models), and/or how the observations are assimilated. For June 21-30, positive SST-MAT, southerly winds, proximity to the ice edge, and negative T500, accompany increased meso-cyclogenesis. However, for September 1-10, surface forcing does not explain frequent comma cloud "polar lows" north-east of the Ross Sea. Inclusion of the upper-level diffluence (e.g., from Z300 field) in the MCP metric, better depicts the observed mesocyclone activity. MCP patterns on these "macro-weather" time scales appear relatively insensitive to the choice of reanalysis.

  14. Seasonal, synoptic and diurnal variation of atmospheric water-isotopologues in the boundary layer of Southwestern Germany caused by plant transpiration, cold-front passages and dewfall.

    NASA Astrophysics Data System (ADS)

    Christner, Emanuel; Dyroff, Christoph; Kohler, Martin; Zahn, Andreas; Gonzales, Yenny; Schneider, Matthias

    2013-04-01

    Atmospheric water is an enormously crucial trace gas. It is responsible for ~70 % of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. The isotopic composition of water vapor is an elegant tracer for a better understanding and quantification of the extremely complex and variable hydrological cycle in Earth's atmosphere (evaporation, cloud condensation, rainout, re-evaporation, snow), which in turn is a prerequisite to improve climate modeling and predictions. As H216O, H218O and HDO differ in vapor pressure and mass, isotope fractionation occurs due to condensation, evaporation and diffusion processes. In contrast to that, plants are able to transpire water with almost no isotope fractionation. For that reason the ratio of isotopologue concentrations in the boundary layer (BL) provides, compared to humidity measurements alone, independent and additional constraints for quantifying the strength of evaporation and transpiration. Furthermore the isotope ratios contain information about transport history of an air mass and microphysical processes, that is not accessible by humidity measurements. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) a commercial Picarro Analyzer L2120-i is operated at Karlsruhe in Southwestern Germany, which is continuously measuring the isotopologues H216O, HDO and H218O of atmospheric water vapor since January 2012. A one year record of H216O, HDO and H218O shows clear seasonal, synoptic and diurnal characteristics and reveals the main driving processes affecting the isotopic composition of water vapor in the Middle European BL. Changes in continental plant transpiration and evaporation throughout the year lead to a slow seasonal HDO/H216O-variation, that cannot be explained by pure Rayleigh condensation. Furthermore, cold-front passages from NW lead to fast and pronounced depletion of the HDO/H216O-ratio within

  15. Winter Storms and Extreme Cold

    MedlinePlus

    ... and weight. Heavier oils congeal more at low temperatures and do not lubricate as well. Thermostat - ensure ... and become slippery. Wind Chill - Windchill is the temperature it “feels like” when you are outside. The ...

  16. Study of a Winter Monsoon Front over the South China Sea by Multi-Sensor Satellite and Weather Radar Data, and a Numerical Model

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Wong, Wai Kin; Dagestad, Knut-Frode; Chan, Pak Wai

    2013-03-01

    An atmospheric frontal system over the South China Sea (SCS) arising from the replenishment of the northeast monsoon is investigated by using multi-sensor satellite data, weather radar data, and a numerical model. The replenishment or freshening of the northeast monsoon results from the merging of high pressure areas over the Chinese Continent. The near-sea surface wind field associated with this event was measured by the Advanced Scatterometer (ASCAT) onboard the European MetOp satellite and the Advanced Synthetic Aperture Radar (ASAR) onboard the European Envisat satellite. The high resolution ASAR image reveals that the frontal line separating this wind field from the synoptic-scale ambient wind field is as sharp as in the case of a cold air outbreak and contains embedded rain cells. Furthermore, it shows that this replenishment was associated with northeasterly winds with speeds of up to 13 ms-1 over the SCS at offshore distances larger than 60 km, but only with speeds of around 6 ms-1 near the coast. The comparison of the observational data with model results of the pre-operational version of the AIR (Atmospheric Integrated Rapid-cycle) forecast model of the Hong Kong Observatory shows that the AIR model can successfully simulate the time evolution of the frontal system and the wind field over the open ocean, but fails to simulate the wind field near the coast.

  17. Implementation of Cold-Cloud Processes in a Source-Oriented WRF/Chem Model to Study a Winter Storm in California

    NASA Astrophysics Data System (ADS)

    Lee, H.; Chen, S.; Kleeman, M.

    2013-12-01

    Mineral dust particles commonly have a favorable arrangement of surface sites that allows them to serve as ice nuclei (IN). Secondary coatings that condense on mineral dust particles may reduce their ability to serve as IN. Both of these effects point to the importance of the particle mixing state when predicting cloud condensation nuclei (CCN) / IN concentrations. The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include cold cloud processes and applied to investigate how source-oriented aerosols influence cloud and ice formation and optical properties in the atmosphere. SOWC tracks 6-dimensional chemical variables (X, Z, Y, Size Bins, Source Types, Species) through an explicit simulation of atmospheric chemistry and physics. Particle radius and number concentration are conserved for each source type and size bin. Simulations in this study use 38 chemical species from 6 emission sources (wood smokes, gasoline, diesel, meat cooking, dust, and other aerosol types) and 8 size bins, spanning the particle diameter range from 0.01 to 10 microns. A new source-oriented hydrometeors module was implemented into the SOWC model to simulate microphysics processes with all source-oriented hydrometeors (cloud, ice, rain, snow and graupel) using the Morrison two-moment microphysics scheme. In our study, all aerosol source types can activate to form cloud droplets based on the Köhler theory, and dust is the only source of IN. We considered the impact of Asian dust on the ice formation in clouds over the Sierra Nevada mountain range during the CalWater field campaign (2011) and estimated dust contributions to total IN concentrations. Aerosols within hydrometeors alter the radiative properties of the cloud droplets. The Goddard shortwave and longwave radiation schemes were modified to interact with source-oriented aerosols and hydrometeors so that aerosol direct and indirect effects could be studied. Geometric-optics approach in the

  18. Ocean backscatter across the Gulf Stream sea surface temperature front

    SciTech Connect

    Nghiem, S.V.; Li, F.K.

    1997-06-01

    Ocean backscatter was measured by the Jet Propulsion Laboratory, with the airborne NUSCAT K{sub u}-band scatterometer, across the Gulf Stream sea surface temperature front during the Surface Wave Dynamics Experiment off the coast of Virginia and Maryland in the winter of 1991. Backscatter across the front between the National Oceanic and Atmospheric Administration experimental coastal buoy A (44024) on the cold side and Discus C buoy (44023) on the warm side shows a difference of more than 5 dB for vertical polarization in many cases. This large frontal backscatter change is observed in all upwind, downwind, and crosswind directions. The sea surface temperature difference measured by the buoys was about 9{degrees}C. The corresponding difference in wind speed cannot account for the large backscatter change in view of geophysical model functions depending only on neutral wind velocity such as SASS. The measured backscatter also has larger upwind-downwind and upwind-crosswind ratios compared to the model results. Furthermore, NUSCAT data reveal that upwind backscatter on the cold side was smaller than or close to crosswind backscatter on the warm side for incidence angles between 30{degrees} to 50{degrees}. This suggests that the temperature front can be detected by the scatterometer at these incidence angles for different wind directions in the cold and warm sides.

  19. Exercising in Cold Weather

    MedlinePlus

    ... www.nia.nih.gov/Go4Life Exercising in Cold Weather Exercise has benefits all year, even during winter. ... activities when it’s cold outside: l Check the weather forecast. If it’s very windy or cold, exercise ...

  20. Winter Weather Frequently Asked Questions

    MedlinePlus

    ... Planning Information on Specific Types of Emergencies Winter Weather Frequently Asked Questions Language: English Español (Spanish) Recommend ... I do if I get stranded in cold weather? Tie a brightly colored cloth to the antenna ...

  1. Annual soil CO2 efflux in a cold temperate forest in northeastern China: effects of winter snowpack and artificial nitrogen deposition.

    PubMed

    Liu, Boqi; Mou, Changcheng; Yan, Guoyong; Xu, Lijian; Jiang, Siling; Xing, Yajuan; Han, Shijie; Yu, Jinghua; Wang, Qinggui

    2016-01-01

    We conducted a snow depth 0 cm (non-snowpack), 10 cm, 20 cm, 30 cm and natural depth) gradient experiment under four quantities of nitrogen addition (control, no added N; low-N, 5 g N m(-2) yr(-1); medium-N, 10 g N m(-2) yr(-1); and high-N, 15 g N m(-2) yr(-1)) and took an-entire-year measurements of soil respiration (Rs) in Korean pine forests in northeastern China during 2013-2014. No evidence for effects of N on Rs could be found during the growing season. On the other hand, reduction of snowpack decreased winter soil respiration due to accompanied relatively lower soil temperature. We found that winter temperature sensitivities (Q10) of Rs were significantly higher than the growing season Q10 under all the N addition treatments. Moderate quantities of N addition (low-N and medium-N) significantly increased temperature sensitivities (Q10) of Rs, but excessive (high-N) addition decreased it during winter. The Gamma empirical model predicted that winter Rs under the four N addition treatments contributed 4.8. ± 0.3% (control), 3.6 ± 0.6% (low-N), 4.3 ± 0.4% (medium-N) and 6.4 ± 0.5% (high-N) to the whole year Rs. Our results demonstrate that N deposition will alter Q10 of winter Rs. Moreover, winter Rs may contribute very few to annual Rs budget. PMID:26732991

  2. Annual soil CO2 efflux in a cold temperate forest in northeastern China: effects of winter snowpack and artificial nitrogen deposition

    PubMed Central

    Liu, Boqi; Mou, Changcheng; Yan, Guoyong; Xu, Lijian; Jiang, Siling; Xing, Yajuan; Han, Shijie; Yu, Jinghua; Wang, Qinggui

    2016-01-01

    We conducted a snow depth 0 cm (non-snowpack), 10 cm, 20 cm, 30 cm and natural depth) gradient experiment under four quantities of nitrogen addition (control, no added N; low-N, 5 g N m−2 yr−1; medium-N, 10 g N m−2 yr−1; and high-N, 15 g N m−2 yr−1) and took an-entire-year measurements of soil respiration (Rs) in Korean pine forests in northeastern China during 2013–2014. No evidence for effects of N on Rs could be found during the growing season. On the other hand, reduction of snowpack decreased winter soil respiration due to accompanied relatively lower soil temperature. We found that winter temperature sensitivities (Q10) of Rs were significantly higher than the growing season Q10 under all the N addition treatments. Moderate quantities of N addition (low-N and medium-N) significantly increased temperature sensitivities (Q10) of Rs, but excessive (high-N) addition decreased it during winter. The Gamma empirical model predicted that winter Rs under the four N addition treatments contributed 4.8. ± 0.3% (control), 3.6 ± 0.6% (low-N), 4.3 ± 0.4% (medium-N) and 6.4 ± 0.5% (high-N) to the whole year Rs. Our results demonstrate that N deposition will alter Q10 of winter Rs. Moreover, winter Rs may contribute very few to annual Rs budget. PMID:26732991

  3. Annual soil CO2 efflux in a cold temperate forest in northeastern China: effects of winter snowpack and artificial nitrogen deposition

    NASA Astrophysics Data System (ADS)

    Liu, Boqi; Mou, Changcheng; Yan, Guoyong; Xu, Lijian; Jiang, Siling; Xing, Yajuan; Han, Shijie; Yu, Jinghua; Wang, Qinggui

    2016-01-01

    We conducted a snow depth 0 cm (non-snowpack), 10 cm, 20 cm, 30 cm and natural depth) gradient experiment under four quantities of nitrogen addition (control, no added N; low-N, 5 g N m-2 yr-1 medium-N, 10 g N m-2 yr-1 and high-N, 15 g N m-2 yr-1) and took an-entire-year measurements of soil respiration (Rs) in Korean pine forests in northeastern China during 2013-2014. No evidence for effects of N on Rs could be found during the growing season. On the other hand, reduction of snowpack decreased winter soil respiration due to accompanied relatively lower soil temperature. We found that winter temperature sensitivities (Q10) of Rs were significantly higher than the growing season Q10 under all the N addition treatments. Moderate quantities of N addition (low-N and medium-N) significantly increased temperature sensitivities (Q10) of Rs, but excessive (high-N) addition decreased it during winter. The Gamma empirical model predicted that winter Rs under the four N addition treatments contributed 4.8. ± 0.3% (control), 3.6 ± 0.6% (low-N), 4.3 ± 0.4% (medium-N) and 6.4 ± 0.5% (high-N) to the whole year Rs. Our results demonstrate that N deposition will alter Q10 of winter Rs. Moreover, winter Rs may contribute very few to annual Rs budget.

  4. Fronts and frontogenesis as revealed by high time resolution data

    NASA Technical Reports Server (NTRS)

    Frank, A. E.; Barber, D. A.

    1977-01-01

    Upper air sounding are used to examine a cold front of average intensity. Vertical cross sections of potential temperature and wind, and horizontal analyses were compared and adjusted for consistency. These analyses were then used to study the evolution of the front, found to consist of a complex system of fronts occurring at all levels of the troposphere. Low level fronts were strongest at the surface and rapidly weakened with height. Fronts in the midddle troposphere were much more intense. The warm air ahead of the fronts was nearly barotropic, while the cold air behind was baroclinic through deep layers. A deep mixed layer was observed to grow in this cold air.

  5. Weather fronts and acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Kveton, Vit

    1991-03-01

    Some methodological aspects are discussed of the investigation of acute infarct myocarditis (AIM) in relation to weather fronts. Results of a new method of analysis are given. Data were analysed from about the hour of the onset of symptoms, and led to the diagnosis of AIM either immediately or within a few hours or days (3019 cases observed over 4.5 years during 1982 1986 in Plzen, Czechoslovakia). Weather classification was based on three factors (the type of the foregoing front, the type of the subsequent front, the time section of the time interval demarcated by the passage of the surfaces of the fronts). AIM occurrence increased in particular types of weather fronts: (i) by 30% during 7 12 h after a warm front, if the time span between fronts exceeded 24 h; (ii) by 10% in time at least 36 h distant from the foregoing cold or occlusion front and from the succeeding warm or occlusion front; (iii) by 20% during 0 2 h before the passage of the front, provided the foregoing front was not warm and the interval between fronts exceeded 5 h. AIM occurrence decreased by 15% 20% for time span between fronts > 24 h at times 6 11, 6 23 and 6 35 h before a coming warm or occlusion front (for interfrontal intervals 25 48, 49 72 and possibly > 72 h), and also at 12 23 and possibly 12 35 h before a cold front (for intervals 49 72 and possibly > 72 h), if the foregoing front was cold or an occlusion front.

  6. PM10 modeling of Beijing in the winter

    NASA Astrophysics Data System (ADS)

    Song, Yu; Zhang, Minsi; Cai, Xuhui

    The megacity of Beijing, China, has had an air pollution problem since the 1990s. The concentrations of particulate matter with an aerodynamic diameter less than 10 μm (PM10) in Beijing in the winter of 2000 were high; the average value of 188 μg m -3 was nearly four times the first grade national standard of 50 μg m -3. The CALPUFF modeling system was used to simulate PM10 dispersion from 1 January 2000 to 29 February 2000. We used near real-time landcover data from the moderate resolution imaging spectroradiometer (MODIS). Statistical evaluation indicated that the model agreed well with the observations. The fluctuations of 24-h PM10 concentrations followed the winter synoptic winds. Cold air from the northwest or north intruded over Beijing for average periods of 4 days in winter, accompanied by high wind speeds. PM10 was swept out of Beijing after the cold fronts and accumulated again once the winds stopped, until the next cold air intrusion. Capital Steel Corporation Limited contributed 46% of the PM10 mass concentrations observed in the Shijingshan industrial area, and had little effect on the eastern part or the center of Beijing. The other industrial regions distributed in southeastern Beijing accounted for an average of 18% of the PM10 in Beijing. Boilers associated with coal consumption mostly for winter heating contributed 31%. Motor vehicles and road dust contributed 5% and 13%, respectively. The total of residential heating in old houses and restaurants contributed approximately 7%. The primary PM10 emissions from electrical generating units were relatively low. Some suggestions are proposed for reducing PM10 pollution in Beijing.

  7. Winter Weeds.

    ERIC Educational Resources Information Center

    Lindberg, Lois

    1981-01-01

    Try to learn all you can about a plant in the winter. As the season changes, you can see what the dried seed pod is like in bloom. You are a convert if you notice a spectacular show of summer wildflowers and wonder what sort of winter weed will result. (Author/CM)

  8. Leap Day 2012 Severe Storm Front

    NASA Video Gallery

    This movie was created using GOES-13 visible and infrared satellite imagery from Feb. 28 at 1245 UTC (7:45 a.m. EST) through March 1, and shows the progression of the cold front and associated low ...

  9. The Barents Sea polar front and water masses variability (1980-2011)

    NASA Astrophysics Data System (ADS)

    Oziel, L.; Sirven, J.; Gascard, J.-C.

    2015-03-01

    The polar front separates the warm and saline Atlantic Waters encountered in the western part of the Barents Sea from the cold and fresh Arctic Waters situated in the northern part. These water masses can mix together, mainly in the eastern part of the Barents Sea, generating dense waters in winter which can cascade into the Arctic Ocean to form the Artic Intermediate Waters. To study the interannual variability and evolution of these water masses and the fronts, we have merged data from the International Council for the Exploration of the Sea and the Arctic and Antarctic Research Institute and have built a new database which covers the period 1980-2011. The summer data is interpolated on a regular grid and a "Probability Density Function" method is used to show that the polar front splits into two branches east of 32° E where the topographic constraint weakens. Two fronts can then be defined: the "Northern Polar Front" is associated with strong salinity gradients and the "Southern Polar Front" with temperature gradients. They enclose the dense Barents Sea Water. The interannual variability of the water masses is apparent in the observed data and is linked to that of the ice cover. In contrast, the link with the Arctic Oscillation is not clear. However, results from a general circulation model suggest that such a link could be found if winter data were taken into account. A strong trend, which amplifies during the last decade, is also found: the Atlantic Water occupies a larger volume of the Barents Sea. This "Atlantification" could be accompanied by a northwards displacement of the southern polar front in the eastern part of the Barents Sea (which is suggested by a model based study) and a decrease of the volume occupied by the Arctic Waters.

  10. Fronts in Large Marine Ecosystems

    NASA Astrophysics Data System (ADS)

    Belkin, Igor M.; Cornillon, Peter C.; Sherman, Kenneth

    2009-04-01

    Oceanic fronts shape marine ecosystems; therefore front mapping and characterization are among the most important aspects of physical oceanography. Here we report on the first global remote sensing survey of fronts in the Large Marine Ecosystems (LME). This survey is based on a unique frontal data archive assembled at the University of Rhode Island. Thermal fronts were automatically derived with the edge detection algorithm of Cayula and Cornillon (1992, 1995, 1996) from 12 years of twice-daily, global, 9-km resolution satellite sea surface temperature (SST) fields to produce synoptic (nearly instantaneous) frontal maps, and to compute the long-term mean frequency of occurrence of SST fronts and their gradients. These synoptic and long-term maps were used to identify major quasi-stationary fronts and to derive provisional frontal distribution maps for all LMEs. Since SST fronts are typically collocated with fronts in other water properties such as salinity, density and chlorophyll, digital frontal paths from SST frontal maps can be used in studies of physical-biological correlations at fronts. Frontal patterns in several exemplary LMEs are described and compared, including those for: the East and West Bering Sea LMEs, Sea of Okhotsk LME, East China Sea LME, Yellow Sea LME, North Sea LME, East and West Greenland Shelf LMEs, Newfoundland-Labrador Shelf LME, Northeast and Southeast US Continental Shelf LMEs, Gulf of Mexico LME, and Patagonian Shelf LME. Seasonal evolution of frontal patterns in major upwelling zones reveals an order-of-magnitude growth of frontal scales from summer to winter. A classification of LMEs with regard to the origin and physics of their respective dominant fronts is presented. The proposed classification lends itself to comparative studies of frontal ecosystems.

  11. Nuclear Winter.

    ERIC Educational Resources Information Center

    Ehrlich, Anne

    1984-01-01

    "Nuclear Winter" was recently coined to describe the climatic and biological effects of a nuclear war. These effects are discussed based on models, simulations, scenarios, and projections. Effects on human populations are also considered. (JN)

  12. Physical characteristics of Eurasian winter temperature variability

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Yul; Son, Seok-Woo

    2016-04-01

    Despite the on-going global warming, recent winters in Eurasian mid-latitudes were much colder than average. In an attempt to better understand the physical characteristics for cold Eurasian winters, major sources of variability in surface air temperature (SAT) are investigated based on cyclostationary EOF analysis. The two leading modes of SAT variability represent the effect of Arctic amplification (AA) and the Arctic oscillation (AO), respectively. These two modes are distinct in terms of the physical characteristics, including surface energy fluxes and tropospheric circulations, and result in significantly different winter SAT patterns over the Eurasian continent. The AA-related SAT anomalies are dipolar with warm Arctic, centered at the Barents–Kara Seas, and cold East Asia. In contrast, the negative AO-related SAT anomalies are characterized by widespread cold anomalies in Northern Eurasia. Relative importance of the AA and the negative AO contributions to cold Eurasian winters is sensitive to the region of interest.

  13. Lateral mixing across ice meltwater fronts of the Chukchi Sea shelf

    NASA Astrophysics Data System (ADS)

    Lu, K.; Weingartner, T.; Danielson, S.; Winsor, P.; Dobbins, E.; Martini, K.; Statscewich, H.

    2015-08-01

    Summer and fall hydrographic sections in the northeastern Chukchi Sea frequently capture 5-20 m thick intrapycnocline lenses or horizontal plumes of warm, moderately salty summer Bering Sea Water flowing northward from Bering Strait. These features occur within the shallow (~20 m depth) pycnocline separating cold, dilute, surface meltwater from near-freezing, salty, winter-formed waters beneath the pycnocline. An idealized numerical model suggests that the features arise from eddies and meanders generated by instability of the surface front separating meltwater from Bering Sea Water. Warm Bering Sea Water is transported across the front and into the pycnocline by the cross-frontal velocities associated with the instabilities. The accompanying lateral eddy heat fluxes may be important both in summer for promoting ice melt and in fall by delaying the onset of ice formation over portions of this shelf. Lateral heat flux magnitudes depend upon the stratification of the Bering Sea Water.

  14. Atmospheric density remote sensing of mesosphere and thermosphere to be used for spacecraft design by adopting VHF radar and HF Doppler sounder at low latitude west Pacific site during winter time

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Johnson, D. L.; Chen, A. J.; Lee, C. C.

    1989-01-01

    Simultaneous observations of VHF radar and HF Doppler array systems located at Chung Li (Taiwan) are used to observe three-dimensional wind speeds and gravity waves. The density perturbations are determined at different altitudes of the mesosphere and thermosphere during weak convective motions of the cold front in the winter. The present observations are believed to be valuable for space projects dealing with the low-latitude atmosphere.

  15. Winter Games.

    ERIC Educational Resources Information Center

    Tarbuth, Lawson, Comp.

    Educators may find activities for indoor and outdoor winter programs in the games of the traditional Eskimo. These games are dominated by few-step operations and low level structural organization. For the most part they are quickly organized, begun, terminated, and ready to be recommenced. All types of games can be found, including quiet ones,…

  16. Winter Workshop.

    ERIC Educational Resources Information Center

    Council of Outdoor Educators of Quebec, Montreal.

    Materials on 11 topics presented at a winter workshop for Quebec outdoor educators have been compiled into this booklet. Action story, instant replay, shoe factory, sound and action, and find an object to fit the description are described and recommended as group dynamic activities. Directions for five games (Superlative Selection; Data…

  17. Winter Wonderlands

    ERIC Educational Resources Information Center

    Coy, Mary

    2011-01-01

    Listening to people complain about the hardships of winter and the dreariness of the nearly constant gray sky prompted the author to help her sixth graders recognize and appreciate the beauty that surrounds them for nearly five months of the year in western New York. The author opines that if students could see things more artistically, the winter…

  18. Radiative magnetized thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The evolution of plane-parallel magnetized thermal conduction fronts in the interstellar medium (ISM) was studied. Separating the coronal ISM phase and interstellar clouds, these fronts have been thought to be the site of the intermediate-temperature regions whose presence was inferred from O VI absorption-line studies. The front evolution was followed numerically, starting from the initial discontinuous temperature distribution between the hot and cold medium, and ending in the final cooling stage of the hot medium. It was found that, for the typical ISM pressure of 4000 K/cu cm and the hot medium temperature of 10 to the 6th K, the transition from evaporation to condensation in a nonmagnetized front occurs when the front thickness is 15 pc. This thickness is a factor of 5 smaller than previously estimated. The O VI column densities in both evaporative and condensation stages agree with observations if the initial hot medium temperature Th exceeds 750,000 K. Condensing conduction fronts give better agreement with observed O VI line profiles because of lower gas temperatures.

  19. Relating Global Precipitation to Atmospheric Fronts

    NASA Astrophysics Data System (ADS)

    Catto, J. L.; Jakob, C.; Nicholls, N.

    2012-12-01

    Atmospheric fronts are important for the day-to-day variability of weather in the midlatitudes, particularly during winter when extratropical storm-tracks are at their maximum intensity. Fronts are often associated with heavy rain, and strongly affect the local space-time distribution of rainfall. Although global climate models should be expected to represent the baroclinic systems within which the fronts are embedded, the fronts themselves and precipitation processes within them are of much smaller scale. As a consequence, models with the typical horizontal resolution of contemporary climate models do not necessarily accurately capture these features. A recently developed objective front identification method applied to reanalysis data is combined with global rainfall data to investigate how precipitation and extremes of precipitation around the globe are associated with atmospheric fronts. Having established the observed distribution of fronts and their role in producing precipitation and extremes, the occurrence of fronts and the associated precipitation can then be evaluated in state-of-the-art climate models. This provides a process-oriented method of model evaluation where the errors in the model can be decomposed into contributions from errors in front frequency and errors in frontal and non-frontal precipitation intensity. Finally, how fronts and their associated precipitation, may change in the future, especially the extremes, can be investigated.

  20. Cloud Front

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02171 Cloud Front

    These clouds formed in the south polar region. The faintness of the cloud system likely indicates that these are mainly ice clouds, with relatively little dust content.

    Image information: VIS instrument. Latitude -86.7N, Longitude 212.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  1. Phospholipase A2 activity during cold acclimation of wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phospholipase A2 (EC 3.1.1.4; PLA2) activity in wheat (Triticum aestivum L.) crown tissue from plants undergoing cold acclimation and/or chilling stress was investigated in a moderately cold tolerant winter wheat, a spring wheat, and a poorly cold tolerant winter wheat. Activity levels were inv...

  2. Titan's Winter Polar Vortex

    NASA Technical Reports Server (NTRS)

    Flasar, F.M.; Achterberg, R.K.; Schinder, P.J.

    2008-01-01

    Titan's atmosphere has provided an interesting study in contrasts and similarities with Earth's. While both have N$_2$ as the dominant constituent and comparable surface pressures $\\sim1$ bar, Titan's next most abundant molecule is CH$_4$, not O$_2$, and the dissociative breakup of CH$_4$ and N$_2$ by sunlight and electron impact leads to a suite of hydrocarbons and nitriles, and ultimately the photochemical smog that enshrouds the moon. In addition, with a 15.95-day period, Titan is a slow rotator compared to Earth. While the mean zonal terrestrial winds are geostrophic, Titan's are mostly cyclostrophic, whipping around the moon in as little as 1 day. Despite the different dynamical regime, Titan's winter stratosphere exhibits several characteristics that should be familiar to terrestrial meteorologists. The cold winter pole near the 1 -mbar level is circumscribed by strong winds (up to 190 m/s) that act as a barrier to mixing with airmasses at lower latitudes. There is evidence of enhancement of several organic species over the winter pole, indicating subsidence. The adiabatic heating associated with this subsidence gives rise to a warm anomaly at the 0.01-mbar level, raising the stratopause two scale heights above its location at equatorial latitudes. Condensate ices have been detected in Titan's lower stratosphere within the winter polar vortex from infrared spectra. Although not always unambiguously identified, their spatial distribution exhibits a sharp gradient, decreasing precipitously across the vortex away from the winter pole. The interesting question of whether there is important heterogeneous chemistry occurring within the polar vortex, analogous to that occurring in the terrestrial polar stratospheric clouds in the ozone holes, has not been addressed. The breakup of Titan's winter polar vortex has not yet been observed. On Earth, the polar vortex is nonlinearly disrupted by interaction with large-amplitude planetary waves. Large-scale waves have not

  3. Extreme Cold: A Prevention Guide to Promote Your Personal Health and Safety

    MedlinePlus

    ... www.bt.cdc.gov/disasters/winter/ hen winter temperatures drop significantly below normal, staying warm and safe can become a chal- lenge. Extremely cold temperatures often accompany a winter storm, so you may ...

  4. First records of winter sea ice concentration in the southwest Pacific sector of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Ferry, Alexander J.; Crosta, Xavier; Quilty, Patrick G.; Fink, David; Howard, William; Armand, Leanne K.

    2015-11-01

    We use a Generalized Additive Model (GAM) to provide the first winter sea ice concentration record from two cores located within the southwest Pacific sector of the Southern Ocean. To compliment the application of GAM, a time series analysis on satellite records of sea ice concentration data was used to extend the standard 13.25 year time series used for paleoceanography. After comparing GAM sea ice estimates with previously published paleo sea ice data we then focus on a new paleo winter sea ice record for marine sediment core E27-23 (59°37.1'S, 155°14.3'E), allowing us to provide a more comprehensive view of winter sea ice dynamics for the southwest Pacific Ocean. The paleo winter sea ice concentration estimates provide the first suggestion that winter sea ice within the southwestern Pacific might have expanded during the Antarctic Cold Reversal. Throughout the Holocene, core E27-23 documents millennial scale variability in paleo winter sea ice coverage within the southwest Pacific. Holocene winter sea ice expansion may have resulted from the Laurentide Ice Sheet deglaciation, increased intensity of the westerly winds, as well as a northern migration of the Subtropical and/or Sub-Antarctic Fronts. Brief consideration is given to the development of a paleo summer sea ice proxy. We conclude that there is no evidence that summer sea ice ever existed at core sites SO136-111 and E27-23 over the last 220 and 52,000 years, respectively.

  5. Climate warming will not decrease winter mortality

    NASA Astrophysics Data System (ADS)

    Staddon, Philip L.; Montgomery, Hugh E.; Depledge, Michael H.

    2014-03-01

    It is widely assumed by policymakers and health professionals that the harmful health impacts of anthropogenic climate change will be partially offset by a decline in excess winter deaths (EWDs) in temperate countries, as winters warm. Recent UK government reports state that winter warming will decrease EWDs. Over the past few decades, however, the UK and other temperate countries have simultaneously experienced better housing, improved health care, higher incomes and greater awareness of the risks of cold. The link between winter temperatures and EWDs may therefore no longer be as strong as before. Here we report on the key drivers that underlie year-to-year variations in EWDs. We found that the association of year-to-year variation in EWDs with the number of cold days in winter ( <5 °C), evident until the mid 1970s, has disappeared, leaving only the incidence of influenza-like illnesses to explain any of the year-to-year variation in EWDs in the past decade. Although EWDs evidently do exist, winter cold severity no longer predicts the numbers affected. We conclude that no evidence exists that EWDs in England and Wales will fall if winters warm with climate change. These findings have important implications for climate change health adaptation policies.

  6. Distribution of alewives in southeastern Lake Ontario in autumn and winter: a clue to winter mortalities

    USGS Publications Warehouse

    Bergstedt, Roger A.; O'Gorman, Robert

    1989-01-01

    Alewives Alosa pseudoharengus in the Great Lakes are thought to avoid extreme cold in winter by moving to deep water where the temperature is usually highest because of inverse thermal stratification. Information collected in Lake Ontario during autumn and winter 1981–1984 with an echo sounder and bottom and midwater trawls indicated that many alewives remained at depths above 110 m, regardless of water temperature. Alewives in the Great Lakes that did not descend to greater depths would be exposed to potentially lethal temperatures during cold winters.inters.

  7. Cold Sores

    MedlinePlus

    ... delivered directly to your desktop! more... What Are Cold Sores? Article Chapters What Are Cold Sores? Cold ... January 2012 Previous Next Related Articles: Canker and Cold Sores Aloe Vera May Help Relieve Mouth Sores ...

  8. Variability in winter climate and winter extremes reduces population growth of an alpine butterfly.

    PubMed

    Roland, Jens; Matter, Stephen F

    2013-01-01

    We examined the long-term, 15-year pattern of population change in a network of 21 Rocky Mountain populations of Parnassius smintheus butterflies in response to climatic variation. We found that winter values of the broadscale climate variable, the Pacific Decadal Oscillation (PDO) index, were a strong predictor of annual population growth, much more so than were endogenous biotic factors related to population density. The relationship between PDO and population growth was nonlinear. Populations declined in years with extreme winter PDO values, when there were either extremely warm or extremely cold sea surface temperatures in the eastern Pacific relative to that in the western Pacific. Results suggest that more variable winters, and more frequent extremely cold or warm winters, will result in more frequent decline of these populations, a pattern exacerbated by the trend for increasingly variable winters seen over the past century. PMID:23600253

  9. Gene expression analysis to understand cold tolerance in citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus cultivars show a wide range of tolerance to cold temperatures. Lemons and limes are known to be sensitive to cold while certain mandarins and trifoliate oranges can endure severe winters. To understand the mechanism of cold tolerance in citrus, we selected three known cold-sensitive and three...

  10. Snowplow Injection Front Effects

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Chandler, M. O.; Buzulukova, N.; Collinson, G. A.; Kepko, E. L.; Garcia-Sage, K. S.; Henderson, M. G.; Sitnov, M. I.

    2013-01-01

    As the Polar spacecraft apogee precessed through the magnetic equator in 2001, Polar encountered numerous substorm events in the region between geosynchronous orbit and 10 RE geocentric distance; most of them in the plasma sheet boundary layers. Of these, a small number was recorded near the neutral sheet in the evening sector. Polar/Thermal Ion Dynamics Experiment provides a unique perspective on the lowest-energy ion plasma, showing that these events exhibited a damped wavelike character, initiated by a burst of radially outward flow transverse to the local magnetic field at approximately 80 km/s. They then exhibit strongly damped cycles of inward/outward flow with a period of several minutes. After one or two cycles, they culminated in a hot plasma electron and ion injection, quite similar to those observed at geosynchronous orbit. Cold plasmaspheric plasmas comprise the outward flow cycles, while the inward flow cycles contain counterstreaming field-parallel polar wind-like flows. The observed wavelike structure, preceding the arrival of an earthward moving substorm injection front, suggests an outward displacement driven by the inward motion at local times closer to midnight, that is, a "snowplow" effect. The damped in/out flows are consistent with interchange oscillations driven by the arrival at the observed local time by an injection originating at greater radius and local time.

  11. Cold intolerance

    MedlinePlus

    ... intolerance is an abnormal sensitivity to a cold environment or cold temperatures. ... can be a symptom of a problem with metabolism. Some people (often very thin women) do not tolerate cold environments because they have very little body fat and ...

  12. Common cold

    MedlinePlus

    ... are the most common reason that children miss school and parents miss work. Parents often get colds ... other children. A cold can spread quickly through schools or daycares. Colds can occur at any time ...

  13. Common Cold

    MedlinePlus

    ... coughing - everyone knows the symptoms of the common cold. It is probably the most common illness. In ... people in the United States suffer 1 billion colds. You can get a cold by touching your ...

  14. Halting Hypothermia: Cold Can Be Dangerous

    MedlinePlus

    ... who spends much time outdoors in very cold weather can get hypothermia. But hypothermia can happen anywhere— ... just outside and not just in bitter winter weather. It can strike when temperatures are cool—for ...

  15. Greater understanding is need of whether warmer and shorter winters associated with climate change could reduce winter mortality

    NASA Astrophysics Data System (ADS)

    Ebi, Kristie L.

    2015-11-01

    In temperate regions, mortality is higher during winter than summer seasons. Assuming this seasonality is associated with ambient temperature, assessments often conclude that climate change will likely reduce winter mortality. However, there has been limited evaluation of the extent to which cold temperatures are actually the proximal cause of winter mortality in temperate regions. Kinney et al (2015 Environ Res. Lett. 10 064016) analyzed multi-decadal data from 39 cities in the US and France and concluded that cold temperatures are not a primary driver of most winter excess mortality. These analyses suggest that increases in heat-related mortality with climate change will unlikely be balanced by reductions in winter mortality, reinforcing the importance of health systems continuing to ensure adequate health protection against cold temperatures even as temperatures warm.

  16. Winter thunderstorms in central Europe in the past and the present

    NASA Astrophysics Data System (ADS)

    Munzar, Jan; Franc, Marek

    Thunderstorms in the territories of the Czech Republic and neighbouring countries are almost exclusively the only phenomena occurring in the warm season. In the cold half of the year, from October to March, an average incidence of thunderstorms is only 2%, with the least occurrence being recorded in January. Yet, winter thunderstorms are dangerous particularly for air traffic because during them, the cloud base is rapidly falling down and visibility is suddenly worsening due to heavy snowfall. Notwithstanding these facts, the issue of their occurrence in the central European space has been paid little attention so far. Long years of study into historical weather extremes in the territory of the Czech Republic revealed over 10 chronicle entries on the occurrence of winter thunderstorms in the period between November and February from the 16th to the beginning of the 20th centuries. The irregular phenomenon was even devoted three occasional prints in central Europe in the second half of the 16th century, two of which were issued in Germany. Fires caused by winter thunderstorms were no sporadic cases. The occurrence of thunderstorms in winter was apparently associated with the passage of pronounced cold fronts. This can be documented on cases from the end of December 1555 when heavy thunderstorms and consequent fires were recorded within a short period of time in Holland, Germany and in Czech lands. It is assumed that the situation in 1627 was similar when a winter thunderstorm was recorded in Prague and in Holešov, southeastern Moravia on 28 December. In February 1581, a thunderstorm in Prague became one of three unusual events publicized by the local occasional newspaper. The beginning of modern studies into winter thunderstorms dates back to the 1960s with the use of lightning flash counters and later also with the use of systems for large-scale lightning flash detection and localization. However, more comprehensive meteorological and climatological assessments of

  17. Novel psychrotolerant picocyanobacteria isolated from Chesapeake Bay in the winter.

    PubMed

    Xu, Yongle; Jiao, Nianzhi; Chen, Feng

    2015-08-01

    Picocyanobacteria are major primary producers in the ocean, especially in the tropical or subtropical oceans or during warm seasons. Many "warm" picocyanobacterial species have been isolated and characterized. However, picocyanobacteria in cold environments or cold seasons are much less studied. In general, little is known about the taxonomy and ecophysiology of picocyanobacteria living in the winter. In this study, 17 strains of picocyanobacteria were isolated from Chesapeake Bay, a temperate estuarine ecosystem, during the winter months. These winter isolates belong to five distinct phylogenetic lineages, and are distinct from the picocyanobacteria previously isolated from the warm seasons. The vast majority of the winter isolates were closely related to picocyanobacteria isolated from other cold environments like Arctic or subalpine waters. The winter picocyanobacterial isolates were able to maintain slow growth or prolonged dormancy at 4°C. Interestingly, the phycoerythrin-rich strains outperformed the phycocyanin-rich strains at cold temperature. In addition, winter picocyanobacteria changed their morphology when cultivated at 4°C. The close phylogenetic relationship between the winter picocyanobacteria and the picocyanobacteria living in high latitude cold regions indicates that low temperature locations select specific ecotypes of picocyanobacteria. PMID:26986796

  18. Worrying about weird winters

    PubMed Central

    Sinclair, Brent

    2014-01-01

    Winter is a key determinant of biological processes in temperate, alpine, and polar environments. Winters are changing, yet we currently lack the knowledge to adequately predict the impacts of climate change on winter biology, or to link winter conditions to the growing-season performance of most organisms.

  19. Measurements of Chlorine Partitioning in the Winter Arctic Stratosphere

    NASA Technical Reports Server (NTRS)

    Stachnik, R.; Salawitch, R.; Engel, A.; Schmidt, U.

    1999-01-01

    Under the extremely cold conditions in the polar winter stratosphere, heterogeneous reactions involving HCl and CIONO(sub 2) on the surfaces of polar stratospheric cloud particles can release large amounts of reactive chlorine from these reservoirs leading to rapid chemical loss of ozone in the Arctic lower stratosphere during late winter and early spring.

  20. Hydrodynamics of superfluid turbulence fronts in He II: steady propagation

    NASA Astrophysics Data System (ADS)

    Geurst, J. A.; van Beelen, H.

    1995-02-01

    A hydrodynamic theory of superfluid turbulent flow of He II which was developed recently is applied to a specific inhomogeneous flow situation, viz. a superfluid turbulence front propagating into an (unstable) state of zero turbulence. It is shown that in a wide range of experimental flow conditions the two equations governing the evolution of the vortex tangle may be uncoupled from the other equations. In the case where the vortex tangle is in internal equilibrium the two vortex-tangle equations may, in addition, be reduced to one non-linear partial differential equation of the first order. It appears that the waves of permanent form permitted by this equation fall apart in two classes, viz. a class of ‘warm’ fronts propagating in the direction of the heat flow and a class of ‘cold’ fronts moving oppositely. The velocity ranges of the warm and cold fronts are separated by a velocity gap. The initial-value problem for front propagation is solved exactly by means of the method of characteristics. A linear analysis of front stability based on that exact solution yields criteria for the selection of the front velocity by requiring marginal stability of the corresponding warm and cold fronts. The significance of marginal stability as a dynamical mechanism for velocity selection was recently put forward by van Saarloos (1988). It is shown that alternative selection criteria for the velocity of warm and cold fronts are provided by the requirements of minimum rate of line-length production and minimum dissipation rate. The comparison of the theoretical values for the velocities of warm and cold fronts with the experimental front velocities reported by Slegtenhorst et al. (1982) for capillary flow of He II looks promising. Wall effects will be taken into account in a separate paper.

  1. Cold Tolerance of Blueberry Genotypes throughout the Dormant Period from Acclimation to Deacclimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold hardiness in woody perennials is determined by complex interacting factors: the timing and rate of cold acclimation; the degree of cold tolerance attained; the maintenance of cold tolerance during the winter; and the rate of loss of cold tolerance or deacclimation upon resumption of spring grow...

  2. Holocene polar front migrations over the Conrad Rise in the Indian sector of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Ikehara, M.; Katsuki, K.; Yokoyama, Y.; Yamane, M.; Khim, B.

    2011-12-01

    The Southern Ocean has played a significant role in the global climate system during the geologic past. In order to understand the paleoceanographic variations with the polar front system and Antarctic Circumpolar Current (ACC), we conducted two cruises KH-07-4 and KH-10-7 in the Indian sector of the Southern Ocean. Two piston cores were collected from the Conrad Rise. We examined centennial-scale changes of diatom assemblages and stable isotopic ratios in planktic foraminifera during the Holocene in a high-accumulation-rate sediment core from the Conrad Rise. Although abundances of dominant diatom taxa (Fragilariopsis kerguelensis and Thalassiothrix antarctica) are comparatively constant, relative abundances of secondary taxa fluctuate. Before ca 9900 cal. yr BP, winter sea-ice and cold water covered the Conrad Rise. Following deglaciation the sea-ice retreated from the Conrad Rise. The Polar Front moved southward during the early Holocene optimum and north Antarctic Zone waters covered the Conrad Rise for about 650 yr. After 9300 cal. yr BP, solar insolation strongly influenced sea surface temperature and primary productivity in the Southern Ocean. In the high-latitude Indian Sector, productivity increased 1500 yr after the onset of late Holocene neoglaciation. Periodic δ18O and cold-water diatom taxa spikes (at intervals of 200 and 300-500 yr, respectively) occurred after 9300 cal. yr BP, probably associated with solar activity. Fluctuations in short-term sea surface temperature and cold-water taxa are synchronous with changes in dD observed in an east Antarctic ice core.

  3. The Gulf Stream - Troposphere connection: warm and cold paths

    NASA Astrophysics Data System (ADS)

    Czaja, Arnaud; Sheldon, Luke; Vanniere, Benoit; Parfitt, Rhys

    2015-04-01

    In this talk, the role of moist processes in ocean-atmosphere coupling over the Gulf Stream will be discussed, using ERA interim reanalysis data (1979-2012) and nested simulations with the UK Met Office Unified Model. The focus is on the cold season (December through February). Two types of moist processes will be highlighted. First, shallow convection driven by surface fluxes of heat and moisture, usually found behind the cold front of extra-tropical cyclones. It will be shown that the warm flank of the Gulf Stream is instrumental in amplifying these convective events. In addition, it will be suggested that they are also responsible for simulated changes in precipitation found in numerical experiments with Atmospheric General Circulation Models forced with smoothed and realistic sea surface temperature (SST) distributions. The impact of this type of air-sea interaction on the larger scale is however unclear as it mostly affects low levels (below 700hPa). The second type of moist processes of relevance is that of moist inertial ascent along the cold front of extra-tropical cyclones. It will be shown that such ascent typically occurs 10% of the time in winter and that it is preferentially rooted over the warm flank of the Gulf Stream. The moist inertial ascent is intense and narrow, and not compensated within a given synoptic system. As a result, and despite being infrequent, it will be shown to contribute crucially to the time mean upward motion over the Gulf Stream at middle (500hPa) and upper tropospheric levels (300 hPa). This result suggests that warm advection by the Gulf Stream acts in effect as a horizontally broad, downward push, on air masses above the boundary layer, a push required to compensate for the upward mass flux in the moist inertial ascent.

  4. Winter Weather at Valley Forge 1777-1778: A Lesson in Climatic Reconstruction.

    ERIC Educational Resources Information Center

    Ansley, Mary Jane; Pritchard, Sandra F.

    1987-01-01

    Notes that the story of George Washington's encampment at Valley Forge is seldom told without reference to the bitter cold winter Washington and his troops endured. Shows how to use historical reports of weather information to allow students to judge for themselves whether the winter at Valley Forge then was harsher than winters in the same area…

  5. Common Cold

    MedlinePlus

    ... News & Events Volunteer NIAID > Health & Research Topics > Common Cold Skip Website Tools Website Tools Print this page ... Help people who are suffering from the common cold by volunteering for NIAID clinical studies on ClinicalTrials. ...

  6. Fronts, fish, and predators

    NASA Astrophysics Data System (ADS)

    Belkin, Igor M.; Hunt, George L.; Hazen, Elliott L.; Zamon, Jeannette E.; Schick, Robert S.; Prieto, Rui; Brodziak, Jon; Teo, Steven L. H.; Thorne, Lesley; Bailey, Helen; Itoh, Sachihiko; Munk, Peter; Musyl, Michael K.; Willis, Jay K.; Zhang, Wuchang

    2014-09-01

    Ocean fronts play a key role in marine ecosystems. Fronts shape oceanic landscapes and affect every trophic level across a wide range of spatio-temporal scales, from meters to thousands of kilometers, and from days to millions of years. At some fronts, there is an elevated rate of primary production, whereas at others, plankton is aggregated by advection and by the behavior of organisms moving against gradients in temperature, salinity, light irradiance, hydrostatic pressure and other physico-chemical and biological factors. Lower trophic level organisms - phytoplankton and zooplankton - that are aggregated in sufficient densities, attract organisms from higher trophic levels, from planktivorous schooling fish to squid, large piscivorous fish, seabirds and marine mammals. Many species have critical portions of their life stages or behaviors closely associated with fronts, including spawning, feeding, ontogenetic development, migrations, and other activities cued to frontal dynamics. At different life stages, an individual species or population might be linked to different fronts. The nature and strength of associations between fronts and biota depend on numerous factors such as the physical nature and spatio-temporal scales of the front and the species and their life stages in question. In other words, fronts support many different niches and micro/macro-habitats over a wide range of spatial and temporal scales.

  7. Physiological processes during winter dormancy and their ecological significance

    SciTech Connect

    Havranek, W.M.; Tranquillini, W.

    1995-07-01

    Lengthy and severe winters require that trees in the forests of boreal and mountain zones undergo winter dormancy. Physiologically, a high resistance to subfreezing temperatures and concomitant dehydration are necessary. To accomplish this dormancy, both physiological and structural changes are needed at the cellular level that require induction by endogenous and photoperiodic control early in autumn. Endogenous rhythmicity promotes cold hardening in early autumn and the persistence of hardiness throughout the winter. Numerous physiological functions are maintained at a reduced level, or become completely inhibited during true winter dormancy. Winter hardiness also includes the capability to minimize water loss effectively when water uptake is severely impeded or impossible. Anatomical features such as tracheids act to minimize xylem embolism during frequent freeze-thaw cycles, and {open_quotes}crown{close_quotes} tissues enable buds to stay in a dehydrated and, thus, more resistant state during winter. Both these structural features are adaptations that contribute to the dominance of conifers in cold climates. Interestingly, deciduous tree species rather than evergreen conifers dominate in the most severe winter climates, although it is not clear whether limitations during winter, during the summer growth period, or during both are most limiting to conifer tree ecology. Additional work that evaluates the importance of winter and summer growth restriction, and their interaction, is needed before a comprehensive understanding of conifer tree ecophysiology will be possible.

  8. Atypical occlusion process caused by the merger of a sea-breeze front and gust front

    NASA Astrophysics Data System (ADS)

    Abulikemu, Abuduwaili; Xu, Xin; Wang, Yuan; Ding, Jinfeng; Wang, Yan

    2015-10-01

    An atypical occlusion process that occurred in North China on 14 July 2011 is studied based on both observations and a real-data Weather Research and Forecasting (WRF) model simulation. The results show that this atypical occlusion process was significantly different from the traditional, synoptic-scale occlusion process that occurs within extratropical cyclones. It was caused by the merger of two cold-type mesoscale fronts. One of the fronts developed from the gust front of convective storms, while the other was a sea-breeze front. As the two fronts moved towards each other, the warm air between them was squeezed and separated from the surface. An atypical occluded front was formed when the two fronts merged, with the warm air forced aloft. This kind of occlusion is termed a "merger" process, different from the well-known "catch-up" and "wrap-up" processes. Moreover, local convection was found to be enhanced during the merger process, with severe convective weather produced in the merger area.

  9. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  10. Radar Backscatter Across the Gulf Stream Sea Surface Temperature Front

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Li, F. K.; Walsh, E. J.; Lou, S. H.

    1998-01-01

    Ocean backscatter signatures were measured by the Jet Propulsion Laboratory airborne NUSCAT K(sub u)-band scatterometer across the Gulf Stream sea surface temperature front. The measurements were made during the Surface Wave Dynamics Experiment (SWADE) off the coast of Virginia and Maryland in the winter of 1991.

  11. [Treatment of winter diseases in summer].

    PubMed

    Gao, Zhi-Ping

    2014-04-01

    To explore the connotation and essence of treatment of winter diseases in summer with analysis and deduction. Treating winter diseases in summer is the concrete embodiment and application of taking advantage of "recuperating yang in spring and summer". Winter diseases are formed by compound factors with deficiency of yangqi as the prerequisite and yin as well as cold as the predominant pathogens. Its pathological characteristic rests with stagnation in meri-dians and collaterals. Aiming at curing chronic diseases, reinforcing yangqi and removing stagnation in meridians and collaterals, treatment in summer is a treating strategy focused on proper opportunity of treatment, which is expected to yield twice the result with half the effort. To select the suitable indications is taken as the core of this treating strategy. And at the same time, blind expansion without careful consideration is not suggested. PMID:24946652

  12. Dehydration in the Winter Arctic Tropopause Region

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Jensen, Eric; Podolske, James; Selkirk, Henry; Anderson, Bruce; Avery, Melody; Diskin. Glenn

    2004-01-01

    Recent work has shown that limited amounts of tropospheric air can penetrate as much as 1 km into the middleworld stratosphere during the arctic winter. This, coupled with temperatures that are cold enough to produce saturation mixing ratios of less than 5 ppmv at the tropopause, results in stratospheric cloud formation and upper tropospheric dehydration. Even though these "cold outbreaks" occupy only a small portion of the area in the arctic (1-2%), their importance is magnified by an order of magnitude because of the air flow through them. This is reinforced by evidence of progressive drying through the winter measured during SOLVE-1. The significance of this process lies in its effect on the upper tropospheric water content of the middle and high latitude tropopause region, which plays an important role in regulating the earth's radiative balance. There appears to be significant year-to-year variability in the incidence of the cold outbreaks. This work has two parts. First, we describe case studies of dehydration taken from the SOLVE and SOLVE2 aircraft sampling missions during the Arctic winters of 2000 and 2003 respectively. Trajectory based microphysical modeling is employed to examine the sensitivity of the dehydration to microphysical parameters and the nature of sub-grid scale temperature fluctuations. We then examine the year-to-year variations in potential dehydration using a trajectory climatology.

  13. Winters fuels report

    SciTech Connect

    1995-10-27

    The outlook for distillate fuel oil this winter is for increased demand and a return to normal inventory patterns, assuming a resumption of normal, cooler weather than last winter. With industrial production expected to grow slightly from last winter`s pace, overall consumption is projected to increase 3 percent from last winter, to 3.4 million barrels per day during the heating season (October 1, 1995-March 31, 1996). Much of the supply win come from stock drawdowns and refinery production. Estimates for the winter are from the Energy Information Administration`s (EIA) 4th Quarter 1995 Short-Tenn Energy Outlook (STEO) Mid-World Oil Price Case forecast. Inventories in place on September 30, 1995, of 132 million barrels were 9 percent below the unusually high year-earlier level. Inventories of high-sulfur distillate fuel oil, the principal type used for heating, were 13 percent lower than a year earlier. Supply problems are not anticipated because refinery production and the ready availability of imports should be adequate to meet demand. Residential heating off prices are expected to be somewhat higher than last winter`s, as the effects of lower crude oil prices are offset by lower distillate inventories. Heating oil is forecast to average $0.92 per gallon, the highest price since the winter of 1992-93. Diesel fuel (including tax) is predicted to be slightly higher than last year at $1.13 per gallon. This article focuses on the winter assessment for distillate fuel oil, how well last year`s STEO winter outlook compared to actual events, and expectations for the coming winter. Additional analyses include regional low-sulfur and high-sulfur distillate supply, demand, and prices, and recent trends in distillate fuel oil inventories.

  14. Cold Pools in the Columbia Basin

    SciTech Connect

    Whiteman, Charles D.; Zhong, Shiyuan; Shaw, William J.; Hubbe, John M.; Bian, Xindi; Mittelstadt, J.

    2001-01-01

    Persistent midwinter cold air pools produce multi-day periods of cold, dreary weather in valleys and basins. Persistent stable stratification leads to the buildup of pollutants and moisture in the pool. Because the pool sometimes has temperatures below freezing while the air above is warmer, freezing precipitation often occurs with consequent effects on transportation and safety. Forecasting the buildup and breakdown of these cold pools is difficult because the physical mechanisms leading to their formation, maintenance, and destruction have received little study. This paper provides a succinct meteorological definition of a cold pool, develops a climatology of Columbia Basin cold pools, and analyzes remote and in situ temperature and wind sounding data for two winter cold pool episodes that were accompanied by fog and stratus, illustrating many of the physical mechanisms affecting cold pool evolution.

  15. Primary cold agglutinin disease: a case report.

    PubMed

    Das, Susanta Kumar; Ghosh, Amritava; Banerjee, Niloy; Khaskil, Sudarshan; Mukherjee, Sabya Sachi

    2012-10-01

    Chronic cold agglutinin disease is a subgroup of auto-immune haemolytic anaemia. Primary cold agglutinin disease has traditionally been defined by the absence of any underlying or associated disease. It usually affects elderly. The term cold refers to the fact that the auto-antibody involved reacts with red cells poorly or not at all at 37 degrees C, whereas it reacts strongly at lower temperature. Here a case of severe pallor, jaundice and red colour urine in winter season for last 10 years diagnosed as a case of primary cold agglutinin disease is reported.The patient was managed conservatively. PMID:23738411

  16. Cold Fusion.

    ERIC Educational Resources Information Center

    Dutton, Eileen; Salazar, Chris

    1998-01-01

    Discusses ways of preparing school-building roofs for the winter season by paying attention to common problem areas. Also highlights the use of white elastomeric roof coatings, their benefits, and considerations when applying them. (GR)

  17. East Asian winter monsoon: results from eight AMIP models

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Sperber, K. R.; Boyle, J. S.; Dix, M.; Ferranti, L.; Kitoh, A.; Lau, K. M.; Miyakoda, K.; Randall, D.; Takacs, L.; Wetherald, R.

    This study evaluates simulations of the East Asian winter monsoon in eight GCMs that participated in the Atmospheric Model Intercomparison Project (AMIP). In addition to validating the mean state of the winter monsoon, the cold surge and its transient properties, which includes the frequency, intensity, preferred propagation tracks, and the evolution patterns of the surges, are examined. GCM simulated temporal distribution of the Siberian high and cold surges is also discussed. Finally, the forcing of the cold surges on the tropical surface wind and convection, along with their interannual variation is analyzed. The mean state of the winter monsoon is generally portrayed well in most of the models. These include the climatological position of the Siberian high, the 200 hPa divergent center, and the large-scale wind patterns at the surface and the 200 hPa. Models display a wide range of skill in simulating the cold surge and its transient properties. In some of the models, the simulated cold surge trajectory, intensity, frequency, propagation patterns and source regions are in general agreement with those from the observed. While in others, the models cannot adequately capture these observed characteristics. The temporal distribution of the Siberian high and cold surges were realistically reproduced in most GCMs. Most models were able to simulate the effect of the cold surges on the tropical surface wind, although a few models unrealistically generated subtropical southerly wind in the mid-winter. The relationship between cold surges and the tropical convection was not satisfactorily simulated in most models. The common discrepancies in the winter monsoon simulation can be attributed to many factors. In some models, the reason is directly related to the improper location of the large-scale convective center near the western Pacific. The satisfactory simulations of the monsoon circulation and the cold surges are partly due to the topographical characteristics of the

  18. [An entomological case report during the winter months: estimation of the post-mortem interval considering the influence of cold temperatures on the development of the forensically important blowfly Calliphora vomitoria].

    PubMed

    Wetzel, Waltraud; Reibe, Saskia; Madea, Burkhard

    2009-01-01

    The authors describe a case report with entomological estimation of the post-mortem interval in the winter months. In early December 2007, the body of a suicide was discovered not far from a lake near Bonn in North Rhine-Westphalia four weeks after the man had disappeared from a hospital. The corpse was very well preserved and did not show any signs of advanced putrefaction. The stage of decomposition did not allow a correct estimation of the time since death. Infestation of insect larvae of the species Calliphora vomitoria was detected in the oral cavity as well as in the self-inflicted deep cut to the throat responsible for death. The age of the larvae was determined by considering the specific minimum threshold of the species (minimum temperature necessary for development). To estimate the time until the blowflies detect the body and start to oviposit, the authors ran an experiment with a pig in a comparable environment with similar temperatures. Altogether, these investigations suggested that the man had committed suicide shortly after disappearing from the hospital. Without the entomological evaluation it would have been very difficult to narrow down the post-mortem interval correctly. PMID:19432091

  19. The effects of phenotypic plasticity on photosynthetic performance in winter rye, winter wheat and Brassica napus.

    PubMed

    Dahal, Keshav; Kane, Khalil; Gadapati, Winona; Webb, Elizabeth; Savitch, Leonid V; Singh, Jasbir; Sharma, Pooja; Sarhan, Fathey; Longstaffe, Fred J; Grodzinski, Bernard; Hüner, Norman P A

    2012-02-01

    The contributions of phenotypic plasticity to photosynthetic performance in winter (cv Musketeer, cv Norstar) and spring (cv SR4A, cv Katepwa) rye (Secale cereale) and wheat (Triticum aestivum) cultivars grown at either 20°C [non-acclimated (NA)] or 5°C [cold acclimated (CA)] were assessed. The 22-40% increase in light-saturated rates of CO₂ assimilation in CA vs NA winter cereals were accounted for by phenotypic plasticity as indicated by the dwarf phenotype and increased specific leaf weight. However, phenotypic plasticity could not account for (1) the differential temperature sensitivity of CO₂ assimilation and photosynthetic electron transport, (2) the increased efficiency and light-saturated rates of photosynthetic electron transport or (3) the decreased light sensitivity of excitation pressure and non-photochemical quenching between NA and NA winter cultivars. Cold acclimation decreased photosynthetic performance of spring relative to winter cultivars. However, the differences in photosynthetic performances between CA winter and spring cultivars were dependent upon the basis on which photosynthetic performance was expressed. Overexpression of BNCBF17 in Brassica napus generally decreased the low temperature sensitivity (Q₁₀) of CO₂ assimilation and photosynthetic electron transport even though the latter had not been exposed to low temperature. Photosynthetic performance in wild type compared to the BNCBF17-overexpressing transgenic B. napus indicated that CBFs/DREBs regulate not only freezing tolerance but also govern plant architecture, leaf anatomy and photosynthetic performance. The apparent positive and negative effects of cold acclimation on photosynthetic performance are discussed in terms of the apparent costs and benefits of phenotypic plasticity, winter survival and reproductive fitness. PMID:21883254

  20. Winter Art Education Project

    ERIC Educational Resources Information Center

    Jokela, Timo

    2007-01-01

    The purpose of this article is to describe how the Department of Art Education at the University of Lapland in Finland has developed winter art as a method of environmental and community-based art education. I will focus on the Snow Show Winter Art Education Project, a training project funded by the European Union and the State Provincial Office…

  1. Synoptic climatological analysis of persistent cold air pools over the Carpathian Basin

    NASA Astrophysics Data System (ADS)

    Szabóné André, Karolina; Bartholy, Judit; Pongrácz, Rita

    2016-04-01

    A persistent cold air pool (PCAP) is a winter-time, anticyclone-related weather event over a relatively large basin. During this time the air is colder near the surface than aloft. This inversion near the surface can last even for weeks. As the cold air cools down, relative humidity increases and fog forms. The entire life cycle of a PCAP depends on the large scale circulation pattern. PCAP usually appears when an anticyclone builds up after a cold front passed over the examined basin, and it is usually destructed by a coming strong cold front of another midlatitude cyclone. Moreover, the intensity of the anticyclone affects the intensity of the PCAP. PCAP may result in different hazards for the population: (1) Temperature inversion in the surface layers together with weak wind may lead to severe air pollution causing health problems for many people, especially, elderly and children. (2) The fog and/or smog during chilly weather conditions often results in freezing rain. Both fog and freezing rain can distract transportation and electricity supply. Unfortunately, the numerical weather prediction models have difficulties to predict PCAP formation and destruction. One of the reasons is that PCAP is not defined objectively with a simple formula, which could be easily applied to the numerical output data. However, according to some recommendations from the synoptic literature, the shallow convective potential energy (SCPE) can be used to mathematically describe PCAP. In this study, we used the ERA-Interim reanalysis datasets to examine this very specific weather event (i.e., PCAP) over the Carpathian Basin. The connection between the mean sea level pressure and some PCAP measures (e.g., SCPE, energy deficit, etc.) is evaluated. For instance, we used logistic regression to identify PCAP periods over the Carpathian Basin. Then, further statistical analysis includes the evaluation of the length and intensity of these PCAP periods.

  2. Radar observations of land breeze fronts.

    NASA Technical Reports Server (NTRS)

    Meyer, J. H.

    1971-01-01

    Description of a radar-observed apparent land breeze front 12 to 14 n mi off the coast of Wallops Island, Va. Accompanying meteorological data show the land breeze at the shore to be a layer of cold air less than 300 ft deep moving seaward at approximately 2 knots. The radar observations show the land breeze vertical frontal surface sloping landward at about 20 deg, with convection over the warm water increasing the layer thickness to 2000 ft near the frontal zone. The radar-observed horizontal frontal surface is a sharp scalloped line echo in the lower 1000 ft, but becomes diffuse above. As the local circulation during daylight hours changes to a sea breeze, the land breeze front recedes toward land and dissipates.

  3. Interannual salinity variability of the Northern Yellow Sea Cold Water Mass

    NASA Astrophysics Data System (ADS)

    Li, Ang; Yu, Fei; Diao, Xinyuan

    2015-05-01

    This paper discusses the interannual variability of the Northern Yellow Sea Cold Water Mass (NYSCWM) and the factors that influence it, based on survey data from the 1976-2006 national standard section and the Korea Oceanographic Data Center, monthly E-P flux data from the European Centre for Medium-Range Weather Forecasts, and meridional wind speed data from the International Comprehensive Ocean-Atmosphere Data Set. The results show that: 1) the mean salinity of the NYSCWM center has a slightly decreasing trend, which is not consistent with the high salinity center; 2) both the southern salinity front and the halocline of the NYSCWM display a weakening trend, which indicates that the difference between the NYSCWM and coastal water decreases; 3) the Yellow Sea Warm Current intrusion, the E-P flux of the northern Yellow Sea, and the strength of the winter monsoon will affect the NYSCWM salinity during the following summer.

  4. Effects of Surface Drag on Fronts within Numerically Simulated Baroclinic Waves.

    NASA Astrophysics Data System (ADS)

    Rotunno, Richard; Skamarock, William C.; Snyder, Chris

    1998-06-01

    A comparative analysis of simulations of baroclinic waves with and without surface drag is presented, with particular reference to surface features. As in recent studies, the present simulations show that, compared to simulations with no drag, those with surface drag are less inclined to develop a secluded warm sector, and that drag weakens the warm front while the cold front remains strong. The authors demonstrate that analogous effects occur when Ekman pumping is used in nonlinear quasigeostrophic numerical simulations of unstable baroclinic waves in a channel. However, since the quasigeostrophic model produces symmetric highs and lows in the unstable baroclinic wave, the cold and warm fronts are therefore also symmetric and hence equally affected by the Ekman pumping. The different effect that friction has on the warm front with respect to the cold front in the primitive-equation simulations is fundamentally related to the tendency for the lows to be strong and narrow and the highs weak and broad, and for the warm front to form just north of, and extend eastward from, the low, while the cold front extends between the high and the low. The authors' thesis is that the Ekman pumping associated with the low, at the location where the warm front would form in the absence of surface friction, acts to resist the formation of the warm front, while the cold front, positioned between the high and the low where Ekman pumping associated with the baroclinic wave is weak, is therefore relatively unaffected.Given the weakness of Ekman pumping associated with the baroclinic wave in the vicinity of the incipient cold front, the present simulations indicate that cold frontogenesis occurs in the drag case in much the same way as in the no-drag case. Present analysis shows that the horizontal advection creating the cold front is a combination of geostrophic and ageostrophic effects. A portion of the ageostrophic frontogenesis is a response to geostrophic frontogenesis, as in the

  5. Numerical study on the velocity structure around tidal fronts in the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Liu, Guimei; Wang, Hui; Sun, Song; Han, Boping

    2003-05-01

    The velocity components across tidal fronts are examined using the Blumberg and Mellor 3-D nonlinear numerical coastal circulation model incorporated with the Mellor and Yamada level 2.5 turbulent closure model based on the reasonable model output of the M2 tide and density residual currents. In the numerical experiments, upwelling motion appears around all the fronts with different velocity structures, accounting for surface cold water around the fronts. The experiments also suggest that the location and formation of fronts are closely related to topography and tidal mixing, as is the velocity structure around the front.

  6. Common cold

    MedlinePlus

    ... often causes a runny nose, nasal congestion, and sneezing. You may also have a sore throat, cough, ... symptoms are: Nasal congestion Runny nose Scratchy throat Sneezing Adults and older children with colds generally have ...

  7. Cold Intolerance

    MedlinePlus

    ... from the Handbook on the Late Effects of Poliomyelitis for Physicians and Survivors © Cold Intolerance Many polio ... index of Handbook on the Late Effects of Poliomyelitis for Physicians and Survivors © Back to top Contact ...

  8. Stories from the Front.

    ERIC Educational Resources Information Center

    Melnick, Blake

    2002-01-01

    Shares some of the author's personal experiences from the "front line" to illustrate the potential of computer-supported learning environments. Concludes that technology, if used in conjunction with sound pedagogy, allows students to tep outside the confines of the traditional classroom and school structure and take responsibility for both their…

  9. Nanoparticle Oscillations and Fronts

    SciTech Connect

    Lagzi, Istvan; Kowalczyk, Bartlomiej; Wang, Dawei; Grzybowski, Bartosz A.

    2010-09-30

    Chemical oscillations can be coupled to the dynamic self-assembly of nanoparticles. Periodic pH changes translate into protonation and deprotonation of the ligands that stabilize the nanoparticles, thus altering repulsive and attractive interparticle forces. In a continuous stirred-tank reactor, rhythmic aggregation and dispersion is observed; in spatially distributed media, propagation of particle aggregation fronts is seen.

  10. Front Range Branch Officers

    NASA Astrophysics Data System (ADS)

    The Front Range Branch of AGU has installed officers for 1990: Ray Noble, National Center for Atmospheric Research, chair; Sherry Oaks, U.S. Geological Survey, chair-elect; Howard Garcia, NOAA, treasurer; Catharine Skokan, Colorado School of Mines, secretary. JoAnn Joselyn of NOAA is past chair. Members at large are Wallace Campbell, NOAA; William Neff, USGS; and Stephen Schneider, NCAR.

  11. Genes critical for the induction of cold acclimation in wheat (Triticum aestivum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phenotypic studies have shown that cold acclimation in wheat and its relatives start at different temperatures. To gain insight into the underlying mechanisms that regulate the induction of cold-acclimation process in cereals we compared the expression of genes in winter-habit (winter Norstar and w...

  12. The role of Xylella fastidiosa cold shock proteins in Pierce’s disease of grapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pierce’s disease of grapevine, caused by the bacterial pathogen Xylella fastidiosa (Xf) is limited to warmer climates, and plant infection can be eliminated by cold winter conditions. Milder winters can increase the likelihood of pathogen persistence from one growing season to the next. Cold adaptat...

  13. The Winter Is Past.

    ERIC Educational Resources Information Center

    Busch, Phyllis S.

    1985-01-01

    Teacher, writer, and naturalist Phyllis S. Busch takes the reader on an early evening woodland walk in March, describing the many changes in plants and animals that are perceptible by sight, smell, and sound as nature awakens from winter. (NEC)

  14. Winter Weather Checklists

    MedlinePlus

    ... Planning Information on Specific Types of Emergencies Winter Weather Checklists Language: English Español (Spanish) Recommend on Facebook ... emergency instructions National Oceanic and Atmospheric Administration (NOAA) weather radio receiver for listening to National Weather Service ...

  15. When hot water freezes before cold

    NASA Astrophysics Data System (ADS)

    Katz, J. I.

    2009-01-01

    I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is due to freezing-point depression by solutes, either gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. The solutes are concentrated ahead of the freezing front by zone refining in water that has not been heated, reducing the temperature of the freezing front, and thereby reducing the temperature gradient and heat flux, slowing the progress of the freezing front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.

  16. Double SST fronts observed from MODIS data in the East China Sea off the Zhejiang-Fujian coast, China

    NASA Astrophysics Data System (ADS)

    He, Shuangyan; Huang, Daji; Zeng, Dingyong

    2016-02-01

    We report a double coastal front system off the Zhejiang (Zhe) and Fujian (Min) Provinces in the East China Sea in winter. In addition to the well-known Zhe-Min offshore coastal front along 50 m isobath, a secondary near-shore coastal thermal front along 20 m isobath is also apparent in December and January. The fronts were observed by Moderate Resolution Imaging Spectroradiometer (MODIS) at monthly mean nighttime sea surface temperature (SST) during 2000-2013 in terms of SST gradients. Our results showed temporal and spatial variations of the two fronts as follows: (1) both offshore front and near-shore front often co-exist between 26.5°N and 29.5°N in December and between 28.0°N and 29.5°N in January. However, only the offshore front is apparent in November and February. (2) The near-shore front is narrow (4-16 km), while the offshore front is three to four times wider (16-48 km). (3) In contrast to the well-known offshore front which exists throughout the winter with a strong intensity, the near-shore front has a shorter lifetime with a weak intensity, and has been overlooked by previous studies. Finally, we proposed that the bottom bathymetric gradients may play an important role in the frontogenesis of the double fronts.

  17. Cold injuries.

    PubMed

    Long, William B; Edlich, Richard F; Winters, Kathryne L; Britt, L D

    2005-01-01

    Exposure to cold can produce a variety of injuries that occur as a result of man's inability to adapt to cold. These injuries can be divided into localized injury to a body part, systemic hypothermia, or a combination of both. Body temperature may fall as a result of heat loss by radiation, evaporation, conduction, and convection. Hypothermia or systemic cold injury occurs when the core body temperature has decreased to 35 degrees C (95 degrees F) or less. The causes of hypothermia are either primary or secondary. Primary, or accidental, hypothermia occurs in healthy individuals inadequately clothed and exposed to severe cooling. In secondary hypothermia, another illness predisposes the individual to accidental hypothermia. Hypothermia affects multiple organs with symptoms of hypothermia that vary according to the severity of cold injury. The diagnosis of hypothermia is easy if the patient is a mountaineer who is stranded in cold weather. However, it may be more difficult in an elderly patient who has been exposed to a cold environment. In either case, the rectal temperature should be checked with a low-reading thermometer. The general principals of prehospital management are to (1) prevent further heat loss, (2) rewarm the body core temperature in advance of the shell, and (3) avoid precipitating ventricular fibrillation. There are two general techniques of rewarming--passive and active. The mechanisms of peripheral cold injury can be divided into phenomena that affect cells and extracellular fluids (direct effects) and those that disrupt the function of the organized tissue and the integrity of the circulation (indirect effects). Generally, no serious damage is seen until tissue freezing occurs. The mildest form of peripheral cold injury is frostnip. Chilblains represent a more severe form of cold injury than frostnip and occur after exposure to nonfreezing temperatures and damp conditions. Immersion (trench) foot, a disease of the sympathetic nerves and blood

  18. 35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. EAST FRONT OF POWERHOUSE AND CAR BARN: East front of powerhouse and car barn. 'Annex' is right end of building. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  19. 9. DETAIL OF INTERIOR OF FRONT PORCH SHOWING FRONT ENTRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. DETAIL OF INTERIOR OF FRONT PORCH SHOWING FRONT ENTRY (LEFT) AND BLANK WALL (CENTER) CORRESPONDING TO LOCATION OF INTERIOR VAULTS. VIEW TO SOUTHEAST. - Boise Project, Boise Project Office, 214 Broadway, Boise, Ada County, ID

  20. View of portion of the front entry on the front ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of portion of the front entry on the front (west) side of the Mueller house, looking northeast. Sheds are in the background. - Ernst Mueller House, 6563 East Avenue, Rancho Cucamonga, San Bernardino County, CA

  1. 3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side elevation. Note gasoline sign post added. Flush store window not altered, 1900 clapboard siding and panelling remaining. - 510 Central Avenue (Commercial Building), Ridgely, Caroline County, MD

  2. American woodcock winter distribution and fidelity to wintering areas

    USGS Publications Warehouse

    Diefenbach, D.R.; Derleth, E.L.; Vander Haegen, W.M.; Nichols, J.D.; Hines, J.E.

    1990-01-01

    We examined winter distribution and fidelity to wintering areas for the American Woodcock (Scolopax minor), which exhibits reversed, sexual size dimorphism. Band-recovery data revealed no difference in winter distributions of different age/sex classes for woodcock from the same breeding areas. Similarly, band recoveries from woodcock banded on wintering grounds revealed no difference in fidelity to wintering sites. Males may winter north of a latitude that is optimal for survival based on physiological considerations, but they gain a reproductive advantage if they are among the first to arrive on the breeding grounds. This may explain our results, which indicate males and females have similar distribution patterns during winter.

  3. Antifreeze Proteins in Winter Rye Leaves Form Oligomeric Complexes1

    PubMed Central

    Yu, Xiao-Ming; Griffith, Marilyn

    1999-01-01

    Antifreeze proteins (AFPs) similar to three pathogenesis-related proteins, a glucanase-like protein (GLP), a chitinase-like protein (CLP), and a thaumatin-like protein (TLP), accumulate during cold acclimation in winter rye (Secale cereale) leaves, where they are thought to modify the growth of intercellular ice during freezing. The objective of this study was to characterize the rye AFPs in their native forms, and our results show that these proteins form oligomeric complexes in vivo. Nine proteins were separated by native-polyacrylamide gel electrophoresis from apoplastic extracts of cold-acclimated winter rye leaves. Seven of these proteins exhibited multiple polypeptides when denatured and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After isolation of the individual proteins, six were shown by immunoblotting to contain various combinations of GLP, CLP, and TLP in addition to other unidentified proteins. Antisera produced against individual cold-induced winter rye GLP, CLP, and TLP all dramatically inhibited glucanase activity in apoplastic extracts from cold-acclimated winter rye leaves, and each antiserum precipitated all three proteins. These results indicate that each of the polypeptides may be exposed on the surface of the protein complexes. By forming oligomeric complexes, AFPs may form larger surfaces to interact with ice, or they may simply increase the mass of the protein bound to ice. In either case, the complexes of AFPs may inhibit ice growth and recrystallization more effectively than the individual polypeptides. PMID:10198095

  4. ARIEL front end

    NASA Astrophysics Data System (ADS)

    Marchetto, M.; Baartman, R. A.; Laxdal, R. E.

    2014-01-01

    The ARIEL project at TRIUMF will greatly expand the variety and availability of radioactive ion beams (RIBs) (Laxdal, Nucl Inst Methods Phys Res B 204:400-409, 2003). The ARIEL front end connects the two ARIEL target stations to the existing ISAC facility to expand delivery to two and eventually three simultaneous RIB beams with up to two simultaneous accelerated beams (Laxdal et al. 2008). The low-energy beam transport lines and mass separators are designed for maximum flexibility to allow a variety of operational modes in order to optimize the radioactive ion beam delivery. A new accelerator path is conceived for high mass delivery from an EBIS charge state breeder. The front-end design utilizes the experience gained in 15 years of ISAC beam delivery.

  5. COLD TRAP

    DOEpatents

    Milleron, N.

    1963-03-12

    An improved linear-flow cold trap is designed for highvacuum applications such as mitigating back migration of diffusion pump oil moiecules. A central pot of liquid nitrogen is nested within and supported by a surrounding, vertical, helical coil of metai sheet, all enveloped by a larger, upright, cylindrical, vacuum vessel. The vertical interstices between successive turns of the coil afford lineal, axial, high-vacuum passages between open mouths at top and bottom of said vessel, while the coil, being cold by virtue of thermal contact of its innermost turn with the nitrogen pot, affords expansive proximate condensation surfaces. (AEC)

  6. A computer model for predicting grapevine cold hardiness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We developed a robust computer model of grapevine bud cold hardiness that will aid in the anticipation of and response to potential injury from fluctuations in winter temperature and from extreme cold events. The model uses time steps of 1 day along with the measured daily mean air temperature to ca...

  7. Nitrification treatment of swine wastewater under cold temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to N load, cold weather nitrification is an important consideration for stabilized performance of biological processes applied to continuous animal production systems. We conducted a winter simulation experiment in the laboratory to evaluate performance of immobilized bacteria under cold...

  8. Membrane stability of winter wheat plants exposed to subzero temperatures for variable lengths of time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to survive episodes of subfreezing temperature is essential to winter wheat. Fully cold-acclimated plants of six lines of winter wheat were exposed to -12, -14, -16 or -18° C, four 1-5 hours. Electrolyte leakage and plant survival were used to assess damage to the plants. Plants exposed ...

  9. Discovering Traits Controlling Winter-hardiness and Spring Regrowth in Diverse Switchgrass Germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Switchgrass (Panicum virgatum L.) is a perennial bioenergy plant that needs to survive both repeated harvests and harsh winters experienced in the Central and Northern USA. The plant traits that control winter-hardiness are not known, but will be critical to the future development of cold-tolerant,...

  10. Front Range Report, Abstracts

    NASA Astrophysics Data System (ADS)

    Spence, William

    The second regional conference of the Front Range Branch, AGU, was attended by more than 80 professionals and some 20 outstanding high school students. The conference included 2 days of interdisciplinary talks, and lots of discussion, that primarily were keyed to geophysical studies of Colorado, Wyoming, and New Mexico. Other talks reported on nonregional, and sometimes global, studies being done by geophypsicists of the Front Range region.Topics included tectonics of the Front Range and the Colorado Plateau, pollution of the Arkansas and Mississippi rivers, and a supreme polluting event that caused the late-Cretaceous extinctions. Other notable talks were on toxic cleanup, microburst (wind shear) detection at U.S. airports, and other meteorological studies. Several talks treated the audience to the excitement of new work and surprise discoveries. The meeting was multimedia, including the playing of two videos through a projection TV and the playing of a fascinating tape between an airport control tower and incoming pilots during a severe microburst event.

  11. Radiative thermal conduction fronts

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-01-01

    The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

  12. Theory of pinned fronts

    NASA Astrophysics Data System (ADS)

    Weissmann, Haim; Shnerb, Nadav M.; Kessler, David A.

    2016-01-01

    The properties of a front between two different phases in the presence of a smoothly inhomogeneous external field that takes its critical value at the crossing point is analyzed. Two generic scenarios are studied. In the first, the system admits a bistable solution and the external field governs the rate in which one phase invades the other. The second mechanism corresponds to a continuous transition that, in the case of reactive systems, takes the form of a transcritical bifurcation at the crossing point. We solve for the front shape and for the response of competitive fronts to external noise, showing that static properties and also some of the dynamical features cannot discriminate between the two scenarios. A reliable indicator turns out to be the fluctuation statistics. These take a Gaussian form in the bifurcation case and a double-peaked shape in a bistable system. Our results are discussed in the context of biological processes, such as species and communities dynamics in the presence of a resource gradient.

  13. Radiative thermal conduction fronts

    NASA Astrophysics Data System (ADS)

    Borkowski, Kazimierz J.; Balbus, Steven A.; Fristrom, Carl C.

    1990-07-01

    The discovery of the O VI interstellar absorption lines in our Galaxy by the Copernicus observatory was a turning point in our understanding of the Interstellar Medium (ISM). It implied the presence of widespread hot (approx. 10 to the 6th power K) gas in disk galaxies. The detection of highly ionized species in quasi-stellar objects' absorption spectra may be the first indirect observation of this hot phase in external disk galaxies. Previous efforts to understand extensive O VI absorption line data from our Galaxy were not very successful in locating the regions where this absorption originates. The location at interfaces between evaporating ISM clouds and hot gas was favored, but recent studies of steady-state conduction fronts in spherical clouds by Ballet, Arnaud, and Rothenflug (1986) and Bohringer and Hartquist (1987) rejected evaporative fronts as the absorption sites. Researchers report here on time-dependent nonequilibrium calculations of planar conductive fronts whose properties match well with observations, and suggest reasons for the difference between the researchers' results and the above. They included magnetic fields in additional models, not reported here, and the conclusions are not affected by their presence.

  14. Thermal Fronts in Solar Flares

    NASA Astrophysics Data System (ADS)

    Karlický, Marian

    2015-12-01

    We studied the formation of a thermal front during the expansion of hot plasma into colder plasma. We used a three-dimensional electromagnetic particle-in-cell model that includes inductive effects. In early phases, in the area of the expanding hot plasma, we found several thermal fronts, which are defined as a sudden decrease of the local electron kinetic energy. The fronts formed a cascade. Thermal fronts with higher temperature contrast were located near plasma density depressions, generated during the hot plasma expansion. The formation of the main thermal front was associated with the return-current process induced by hot electron expansion and electrons backscattered at the front. A part of the hot plasma was trapped by the thermal front while another part, mainly with the most energetic electrons, escaped and generated Langmuir and electromagnetic waves in front of the thermal front, as shown by the dispersion diagrams. Considering all of these processes and those described in the literature, we show that anomalous electric resistivity is produced at the location of the thermal front. Thus, the thermal front can contribute to energy dissipation in the current-carrying loops of solar flares. We estimated the values of such anomalous resistivity in the solar atmosphere together with collisional resistivity and electric fields. We propose that the slowly drifting reverse drift bursts, observed at the beginning of some solar flares, could be signatures of the thermal front.

  15. Winter precipitation change in South China in recent decades

    NASA Astrophysics Data System (ADS)

    Cai, Jingning

    2013-04-01

    Precipitation change is one of important climate researches in China, but winter precipitation variation in South China has not been studied so frequently. In China, it is rainy when hot; so summer precipitation is usually one focus in research, esp. in South China. However, winter precipitation and its change influence people profoundly in South China, also. The most recent example is what happened over South China in winter 2008. In this winter, millions of people suffered from the unusual cold and snowy winter. It led to huge loss in economy and traffic as well. Roads closed and railway stations were jammed and crowded with people; many planes were grounded for heavy snow and bad weather. Transmission lines faulted in the mountains. The ommunication signals were affected. Everyday food supply including vegetables and meats had to be delayed or interrupted. In some city even water supply was interrupted. And garbage in the city was piled up. Just in this winter the snow depth and coverage area in many places in South China broke or equaled the historical records. In fact, it isn't the only one unusual winter precipitation event in South China. Since 1950s, several freezing and snowy winters struck the South in China. In this research, winter precipitation change in recent years in South China has been discussed based on the precipitation observations. The associated large scale atmospheric circulation change is also analyzed. It is found that snowy winter in South China hardly comes in most periods of 2000s, but in recent decades this heavy snow in winter has appeared several times as observations shows. This phenomenon could be related to the large scale atmospheric circulation change.

  16. Project COLD.

    ERIC Educational Resources Information Center

    Kazanjian, Wendy C.

    1982-01-01

    Describes Project COLD (Climate, Ocean, Land, Discovery) a scientific study of the Polar Regions, a collection of 35 modules used within the framework of existing subjects: oceanography, biology, geology, meterology, geography, social science. Includes a partial list of topics and one activity (geodesic dome) from a module. (Author/SK)

  17. Cold Sores

    MedlinePlus

    ... causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 usually affects the genital area Some people have no symptoms from the ...

  18. Taxonomy of Greater White-fronted Geese (Aves: Anatidae)

    USGS Publications Warehouse

    Banks, Richard C.

    2011-01-01

    Five subspecies of the Greater White-fronted Goose, Anser albifrons (Scopoli, 1769), have been named, all on the basis of wintering birds, and up to six subspecies have been recognized. There has been confusion over the application of some names, particularly in North America, because of lack of knowledge of the breeding ranges and type localities, and incorrect taxonomic decisions. There is one clinally varying subspecies in Eurasia, one that breeds in Greenland, and three in North America, one newly named herein.

  19. Characterising Cold Weather for the UK mainland

    NASA Astrophysics Data System (ADS)

    Fradley, Kate; Dacre, Helen; Ambaum, Maarten

    2016-04-01

    Excess Winter Mortality is a peak in the population's mortality rate during winter months and is correlated with low outdoor temperatures. Excess Winter Mortality has adverse impacts, including increased demand on health services. The management of resources for such increased demands maybe improved through incorporation of weather forecasting information to advanced warnings. For the UK, prolonged cold periods are associated with easterly advection, and high pressure systems. Characterisation of the synoptic conditions associated with cold periods is important to understand forecast performance. Principal Component Analysis has been used with mean sea level pressure from 35 years of ERA interim reanalysis to capture synoptic variability on a continuous scale. Cold events in the North and South of the UK mainland have been identified as having different synoptic variability using this method. Furthermore extending the Principal Component Analysis to investigate the skill of forecasts has identified systematic under prediction of some cold weather synoptic conditions. Ensemble forecasts are used to quantify the uncertainty associated with these cold weather synoptic conditions. This information maybe be used to improve the value of existing weather warnings.

  20. Strong Costs and Benefits of Winter Acclimatization in Drosophila melanogaster

    PubMed Central

    Schou, Mads Fristrup; Loeschcke, Volker; Kristensen, Torsten Nygaard

    2015-01-01

    Studies on thermal acclimation in insects are often performed on animals acclimated in the laboratory under conditions that are not ecologically relevant. Costs and benefits of acclimation responses under such conditions may not reflect costs and benefits in natural populations subjected to daily and seasonal temperature fluctuations. Here we estimated costs and benefits in thermal tolerance limits in relation to winter acclimatization of Drosophila melanogaster. We sampled flies from a natural habitat during winter in Denmark (field flies) and compared heat and cold tolerance of these to that of flies collected from the same natural population, but acclimated to 25 °C or 13 °C in the laboratory (laboratory flies). We further obtained thermal performance curves for egg-to-adult viability of field and laboratory (25 °C) flies, to estimate possible cross-generational effects of acclimation. We found much higher cold tolerance and a lowered heat tolerance in field flies compared to laboratory flies reared at 25 °C. Flies reared in the laboratory at 13 °C exhibited the same thermal cost-benefit relations as the winter acclimatized flies. We also found a cost of winter acclimatization in terms of decreased egg-to-adult viability at high temperatures of eggs laid by winter acclimatized flies. Based on our findings we suggest that winter acclimatization in nature can induce strong benefits in terms of increased cold tolerance. These benefits can be reproduced in the laboratory under ecologically relevant rearing and testing conditions, and should be incorporated in species distribution modelling. Winter acclimatization also leads to decreased heat tolerance. This may create a mismatch between acclimation responses and the thermal environment, e.g. if temperatures suddenly increase during spring, under current and expected more variable future climatic conditions. PMID:26075607

  1. Winter depression and diabetes.

    PubMed

    Ernst, Christine R

    2012-12-01

    Depression is a common and often harmful disorder, which is frequently associated with the winter season. Research has shown a link between type 2 diabetes mellitus and depression. Furthermore, diabetics with depression have a higher rate of adverse outcomes. Little has been published regarding the seasonality of depression in diabetics. The case report described in this article concerns a 65-year-old woman with type 2 diabetes and a history of winter depression. Current evidence-based management options are reviewed. PMID:23089656

  2. Link between warm conveyor belts and fronts and the impact on extreme rainfall

    NASA Astrophysics Data System (ADS)

    Catto, Jennifer; Madonna, Erica; Joos, Hanna; Wernli, Heini; Rudeva, Irina; Simmonds, Ian

    2015-04-01

    The various dynamical features within extratropical cyclones have been shown to be very important for the precipitation produced by these systems. Warm conveyor belts (WCBs) and fronts are both strongly associated with total and extreme precipitation in the midlatitudes. Here we have brought together two automated feature detection methods to answer questions on the frequency of matching of fronts and WCBs, whether this depends on frontal type or height of WCB, and the impact this matching has on extreme precipitation events. We find that WCBs and fronts are strongly related in the midlatitudes - annually 60% of WCBs are associated with cold fronts and around 50% associated with warm fronts, and a fairly large proportion associated with both together. The frequency of linked WCBs and fronts shows a strong seasonal cycle. In some regions warm fronts are more strongly linked to WCBs than cold fronts. To the east of Australia in particular, there are often WCBs not associated with fronts at all. Fronts that co-occur with a WCB are much more likely to produce an extreme precipitation event.

  3. Coastal circulation off southern Tamaulipas and northern Veracruz, western Gulf of Mexico, during winter 2012-2013

    NASA Astrophysics Data System (ADS)

    Rivas, David

    2015-04-01

    Four months of observations from a near-coastal mooring deployed off southern Tamaulipas-northern Veracruz coast (western Gulf of Mexico) during winter 2012-2013 provides velocity, temperature, and salinity series in a region where apparently no in-situ measurements have been formally reported. The measurements show numerous events of intense alongshore velocities with magnitudes typically exceeding 80 cm/s, associated with intensified winds associated with the cold fronts invading the western Gulf during fall-winter, via coastal-trapped motions coming from northern locations. These motions must induce a coastal jet that modulates the regional along-shelf transports. This notion is corroborated by an analytical coastal-trapped wave (CTW) model which explains most of the variability of the sea level and the alongshore barotropic velocity observed in the mooring. Several near-inertial signals exceeding 50 cm/s are also observed at the surface levels. These high-frequency (HF) signals occur several hours before the intensified currents induced by the winds. Comparison between HF series of water velocity and wind suggests a direct influence of the winds affecting the NW Gulf (northern Tamaulipas/southern Texas) about 6-9 hours before the occurrence of the HF currents at the mooring. These near-inertial events induce a vigorous mixing of the local riverine discharge.

  4. Characteristics of winter precipitation systems over the mid-latitude North Pacific as analyzed from TRMM PR and VIRS data

    NASA Astrophysics Data System (ADS)

    Shimizu, H.; Masunaga, H.; Yamamoto, M. K.; Higuchi, A.

    2011-12-01

    Winter precipitation systems over the mid-latitude North Pacific are investigated using multiple sensors on board the Tropical Rainfall Measuring Mission (TRMM) satellite. The present study is focused on the vertical structure of precipitation in 11 winters. The vertical structure is diagnosed with echo-top height from the Precipitation Radar (PR) and the equivalent cloud-top height from the Visible Infrared and Scanner (VIRS) and Japanese 25-year Reanalysis (JRA-25). Precipitation systems are classified into three categories based on their vertical structure: Shallow Cumulus (SCu), Middle Systems (MdS), and Deep Convection (DpC). This categorization method is found to clearly delineate a systematic difference in precipitation between the east and west Pacific. To further explore the nature of precipitation systems, Cold Outbreak (CO), Extra-tropical Cyclone (EC), Front (F), and Sub tropical Cyclone (ST) patterns are identified by infrared imagery and upper level pressure. The zonal gradient across the Pacific in the vertical structure of precipitation may be interpreted in terms of these synoptic-scale disturbances superposed with different proportions.

  5. Two cold-season derechoes in Europe

    NASA Astrophysics Data System (ADS)

    Gatzen, Christoph; Púčik, Tomas; Ryva, David

    2011-06-01

    In this study, we apply for the first time the definition of a derecho (Johns and Hirt, 1987) to European cold-season convective storm systems. These occurred on 18 January 2007 and 1 March 2008, respectively, and they are shown to fulfill the criteria of a derecho. Damaging winds were reported over a distance of 1500 km and locally reached F3 intensity. Synoptic analysis for the events reveal strongly forced situations that have been described for cold-season derechoes in the United States. A comparison of swaths of damaging winds, radar structures, detected lightning, cold pool development, and cloud-top temperatures indicates that both derechoes formed along cold fronts that were affected by strong quasi-geostrophic forcing. It seems that the overlap of the cold front position with the strong differential cyclonic vorticity advection at the cyclonic flank of mid-level jet streaks favoured intense convection and high winds. The movement and path width of the two derechoes seemed to be related to this overlap. The wind gust intensity that was also different for both events is discussed and could be related to the component of the mid-level winds perpendicular to the gust fronts.

  6. Logistic Regression Analysis of the Response of Winter Wheat to Components of Artificial Freezing Episodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improvement of cold tolerance of winter wheat (Triticum aestivum L.) through breeding methods has been problematic. A better understanding of how individual wheat cultivars respond to components of the freezing process may provide new information that can be used to develop more cold tolerance culti...

  7. Hot, Cold, and Really Cold.

    ERIC Educational Resources Information Center

    Leyden, Michael

    1997-01-01

    Describes a physics experiment investigating temperature prediction and the relationship between the physical properties of heat units, melting, dissolving, states of matter, and energy loss. Details the experimental setup, which requires hot and cold water, a thermometer, and ice. Notes that the experiment employs a deliberate counter-intuitive…

  8. Nuclear Winter: Implications for civil defense

    SciTech Connect

    Chester, C.V.; Perry, A.M.; Hobbs, B.F.

    1988-05-01

    ''Nuclear Winter'' is the term given to the cooling hypothesized to occur in the Northern Hemisphere following a nuclear war as the result of the injection of smoke from burning cities into the atmosphere. The voluminous literature on this subject produced since the paper was published in 1983 by Turco, Toon, Ackerman, Pollack, and Sagen (TTAPS) has been reviewed. Three-dimensional global circulation models have resulted in reduced estimates of cooling---15 to 25/degree/C for a summer war and a few degrees for a winter war. More serious may be the possibility of suppression of convective precipitation by the altered temperature profiles in the atmosphere. However, very large uncertainties remain in input parameters, the models, and the results of calculations. We believe the state of knowledge about nuclear winter is sufficiently developed to conclude: Neither cold nor drought is likely to be a direct threat to human survival for populations with the wherewithal to survive normal January temperatures. The principal threat from nuclear winter is to food production, and this could present problems to third parties who are without food reserves. Loss of a crop year is neither a new nor an unexpected threat from nuclear war to the United States and the Soviet Union. Both have at least a year's food reserve at all times. Both face formidable organizational problems in distributing their reserves in a war-damaged environment. The consequences of nuclear winter could be expected to fall more heavily on the Soviet Union than the United States due to its higher latitude and less productive agriculture. This may be especially true if disturbances of rainfall amounts and distribution persist for more than a year.

  9. Nuclear Winter: The implications for civil defense

    SciTech Connect

    Chester, C.V.; Perry, A.M.; Hobbs, B.F.

    1987-01-01

    ''Nuclear Winter'' is the term given to hypothesized cooling in the northern hemisphere following a nuclear war due to injection of smoke from burning cities into the atmosphere. The voluminous literature on this subject produced since the original paper in 1983 by Turco, Toon, Ackerman, Pollack, and Sagen (TTAPS) has been reviewed. The widespread use of 3-dimensional global circulation models have resulted in reduced estimates of cooling; 15 to 25/sup 0/C for a summer war and a few degrees for a winter war. More serious may be the possibility of suppression of convective precipitation by the altered temperature profiles in the atmosphere. However, very large uncertainties remain in input parameters, the models, and the results of calculations. We believe the state of knowledge about nuclear winter is sufficiently developed to conclude: Neither cold nor drought are likely to be direct threats to human survival for populations with the wherewithal to survive normal January temperatures; The principal threat from nuclear winter is to food production, and could present problems to third parties without food reserves; and Loss of a crop year is neither a new nor unexpected threat from nuclear war to the US and the Soviet Union. Both have at least a year's food reserve at all times. Both face formidable organizational problems in distributing their reserves in a war-damaged environment. The consequences of nuclear winter could be expected to fall more heavily on the Soviet Union than the US due to its higher latitude and less productive agriculture. This may be especially true if disturbances of rainfall amounts and distribution persist for more than a year. 6 refs.

  10. Teaching Ecology in Winter.

    ERIC Educational Resources Information Center

    Clearing: Nature and Learning in the Pacific Northwest, 1984

    1984-01-01

    Presents ideas for teaching ecology in the winter. Suggested topic areas or units include snow insulation and density, snowflakes and snow crystals, goldenrod galls, bird behavior, survival techniques, bacteriology and decomposition, trees and keying, biomass and productivity, pollution, and soil organisms. A sample student activity sheet is…

  11. The News. Winter 2007

    ERIC Educational Resources Information Center

    Giles, Ray, Ed.

    2007-01-01

    This Winter 2007 quarterly newsletter from the Community College League of California includes: (1) Incumbents: Some Win, Some Lose in November Trustee Elections; (2) Voters Approve $2 Billion in Bonds; (3) Photos from the "Together We Can" conference; (4) Report, Media Criticize Transfer, Completion Rates and Colleges; (5) District Leader…

  12. Winter Playscape Dreaming

    ERIC Educational Resources Information Center

    Keeler, Rusty

    2006-01-01

    Winter, like all seasons, adds a new sense of mystery and discovery to the world of young children. It is the time when they can study snowflakes, find icicles, or observe the birds that share their yards. This article presents ideas and suggestions on how to plan a playscape. A playscape is a man-made seasonal playground for young children. It…

  13. Titan's Emergence from Winter

    NASA Technical Reports Server (NTRS)

    Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

    2011-01-01

    We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

  14. Structure and Propagation of Fronts East of the Rocky Mountains and Their Relationship to Precipitation

    NASA Astrophysics Data System (ADS)

    Martin, Jonathan Edward

    1992-01-01

    The role of frontogenetic processes in generating and distributing precipitation east of the Rocky Mountains in the United States is examined using data collected during the Genesis of Atlantic Lows Experiment (GALE). A set of mid-tropospheric, frontogenetic, precipitation -producing features are discussed. A recurrent, non-classical, synoptic scale structure characterized these cases. Based on observations from four cases, a conceptual model is proposed for these structures; the cold frontogenesis aloft (CFA) model. In one case study, the secondary circulation about an upper-level front, in a region of conditional symmetric instability (CSI), produced a rainband of moderate intensity. The potential influence of upper-level frontogenesis processes on the evolution of the CSI is explored through Lagrangian, adiabatic changes in the equivalent potential vorticity. The interactions between a surface cold front and an upper-level front that resulted in the production of a deep, precipitating frontal structure is examined. An increase in the vigor of the frontal convection is attributed to favorable vertical superposition of the surface cold front and the upper-level front. Mid-level latent heat release was likely responsible for the diabatic steepening of the dynamic tropopause. This steepening contributed to the subsequent rapid development of a surface cyclone on the East Coast. The mesoscale structure and distribution of precipitation along a surface cold front is investigated. The precipitation cores in a narrow cold-frontal rainband (NCFR) showed some differences, as well as similarities, to previously observed NCFRs. A correspondence between precipitation intensity and the slope of the frontal surface was observed for a wide cold-frontal rainband (WCFR) associated with this cold front. The nature of this correspondence is investigated and some possible mechanisms for changing the slope of the frontal topography are examined.

  15. DEACCLIMATION AND REACCLIMATION OF COLD-HARDY PLANTS: CURRENT UNDERSTANDING AND EMERGING CONCEPTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of cold-hardy plants to resist deacclimation during transient warm spells and to reacclimate when cold temperatures return are significant for winter survival. Yet compared to the volume of research on the biology of cold acclimation, relatively little is known about how plants maintain...

  16. From the front

    SciTech Connect

    Price, Stephen

    2009-01-01

    The causes of recent dynamic thinning of Greenland's outlet glaciers have been debated. Realistic simulations suggest that changes at the marine fronts of these glaciers are to blame, implying that dynamic thinning will cease once the glaciers retreat to higher ground. For the last decade, many outlet glaciers in Greenland that terminate in the ocean have accelerated, thinned, and retreated. To explain these dynamic changes, two hypotheses have been discussed. Atmospheric warming has increased surface melting and may also have increased the amount of meltwater reaching the glacier bed, increasing lubrication at the base and hence the rate of glacier sliding. Alternatively, a change in the delicate balance of forces where the glacier fronts meet the ocean could trigger the changes. Faezeh Nick and colleagues5 present ice-sheet modeling experiments that mimic the observations on Helheim glacier, East Greenland, and suggest that the dynamic behaviour of outlet glaciers follows from perturbations at their marine fronts. Greenland's ice sheet loses mass partly through surface melting and partly through fast flowing outlet glaciers that connect the vast plateau of inland ice with the ocean. Earlier ice sheet models have failed to reproduce the dynamic variability exhibited by ice sheets over time. It has therefore not been possible to distinguish with confidence between basal lubrication from surface meltwater and changes at the glaciers' marine fronts as causes for the observed changes on Greenland's outlet glaciers. But this distinction bears directly on future sea-level rise, the raison d'etre of much of modern-day glaciology: If the recent dynamic mass loss Greenland's outlet glaciers is linked to changing atmospheric temperatures, it may continue for as long as temperatures continue to increase. On the other hand, if the source of the dynamic mass loss is a perturbation at the ice-ocean boundary, these glaciers will lose contact with that perturbation after a finite

  17. Chilling Out with Colds

    MedlinePlus

    ... most common cold virus, but more than 200 viruses can cause colds. Because there are so many, ... to help you feel better. Take that, cold viruses! continue How Kids Catch Colds Mucus (say: MYOO- ...

  18. Coping with Cold Sores

    MedlinePlus

    ... Here's Help White House Lunch Recipes Coping With Cold Sores KidsHealth > For Kids > Coping With Cold Sores ... sore." What's that? Adam wondered. What Is a Cold Sore? Cold sores are small blisters that is ...

  19. Factors affecting outdoor exposure in winter: population-based study

    NASA Astrophysics Data System (ADS)

    Mäkinen, Tiina M.; Raatikka, Veli-Pekka; Rytkönen, Mika; Jokelainen, Jari; Rintamäki, Hannu; Ruuhela, Reija; Näyhä, Simo; Hassi, Juhani

    2006-09-01

    The extent of outdoor exposure during winter and factors affecting it were examined in a cross-sectional population study in Finland. Men and women aged 25-74 years from the National FINRISK 2002 sub-study ( n=6,591) were queried about their average weekly occupational, leisure-time and total cold exposure during the past winter. The effects of gender, age, area of residence, occupation, ambient temperature, self-rated health, physical activity and education on cold exposure were analysed. The self-reported median total cold exposure time was 7 h/week (8 h men, 6 h women),<1 h/week (2 h men, 0 h women) at work, 4 h/week (5 h men, 4 h women) during leisure time and 1 h/week (1 h men, 1.5 h women) while commuting to work. Factors associated with increased occupational cold exposure among men were: being employed in agriculture, forestry and industry/mining/construction or related occupations, being less educated and being aged 55-64 years. Factors associated with increased leisure-time cold exposure among men were: employment in industry/mining/construction or related occupations, being a pensioner or unemployed, reporting at least average health, being physically active and having college or vocational education. Among women, being a housewife, pensioner or unemployed and engaged in physical activity increased leisure-time cold exposure, and young women were more exposed than older ones. Self-rated health was positively associated with leisure time cold exposure in men and only to a minor extent in women. In conclusion, the subjects reported spending 4% of their total time under cold exposure, most of it (71%) during leisure time. Both occupational and leisure-time cold exposure is greater among men than women.

  20. Sea-surface temperature fronts in the Yellow and East China Seas from TRMM microwave imager data

    NASA Astrophysics Data System (ADS)

    Huang, Daji; Zhang, Tao; Zhou, Feng

    2010-06-01

    Swath data from the Tropical Rainfall Measuring Mission microwave imager of sea-surface temperatures (SST) from 1998 to 2005 have been used to analyze the climatology and seasonal variability of the SST fronts in the Yellow and East China Seas (YES). Seven fronts have been identified and placed into three categories, namely, (1) the shelf-break front (Kuroshio Front), (2) the coastal fronts (Zhe-Min, Jiangsu, Shangdong Peninsula, Western Korean, and Western Chejudo Fronts), and (3) the shelf front (Western Yellow Sea Shelf Front). The Kuroshio Front exists from December through May, with the maximum SST gradient and highest frontal probability in April. The five coastal fronts exist year-round, all with their maximum SST gradient and highest frontal probability in February. The shelf front in the western Yellow Sea exists only from January to March. Frontogenesis in winter is due to effects of both air-sea heat exchange and advection by currents. The coastal fronts in the stratified months are expressed as tidal fronts. The coastal frontal zones coincide with the major spawning grounds of fish in the YES. The overwintering fishery ground in the Yellow Sea overlaps with the narrow band of favorable water temperature in the frontal zone. The overwintering grounds in the East China Sea are broad and bounded by fronts.

  1. Canoeists' disorientation following cold immersion

    PubMed Central

    Baker, S.; Atha, J.

    1981-01-01

    As an initial step to a broader study of the disorientating effects of cold water immersions on top class competitive canoeists a survey was made of the incidence of hazardous immersions amongst a majority sample of the better canoeists in the country. Virtually the entire entry to one of the most important national competitive meets was canvassed. A total of 288 canoeists in the 1st and 2nd divisions were identified and asked to participate. Replies were received from 247 (86%). All those responding had had extensive experience of canoeing in winter spate and were capable of fast and efficient first-time canoe rolls in cases of capsize. Particular interest was focussed on the 85 (34%) who had experienced at least one capsize in cold water during training or competition in mid-winter. Respondents viewed the winter capsize seriously. Despite their familiarity with the conditions in which they trained all 85, recalling their capsize experiences, reported being concerned, most (79%) only modestly so, but a significant proportion (21%) confessed to feelings of extreme alarm. A number of marked physical symptoms that regularly attend on a capsize were widely reported, the most usual of which was severe pain in the forehead (89%) and breathing and speaking difficulties when afloat (64%). Additionally 62% reported sensory problems including visual difficulties, dizziness and disorientation. Five canoeists admitted fainting. Despite these hazards few preventive measures were taken and clothing with negligible thermal insulation properties was commonly worn. It is concluded that transient cold immersions can be disturbing, and can disorientate the canoeist, but that although conscious of this and to his own potentially high cost, he takes little notice of it in his desire to compete successfully. Imagesp111-ap111-bp112-ap113-ap114-a PMID:7272652

  2. Deciduous Plant Twigs in Winter

    ERIC Educational Resources Information Center

    Clark, Eloise

    1977-01-01

    Describing, via illustration and narrative, the winter twigs found in the U.S., this article presents a sophisticated discussion of: beech, white ash, aspen, sycamore, red oak, butternut, and other winter twigs. (JC)

  3. Farmers’ Market Expands to Offer Products in Winter | Poster

    Cancer.gov

    By Carolynne Keenan, Contributing Writer The 2013 National Cancer Institute (NCI) at Frederick Farmers’ Market regular season may have closed, but that doesn’t mean customers who want fresh produce, handmade crafts, and other homemade goodies from local vendors are out of luck. Winter Markets, which began Jan. 7, will be held every other Tuesday, from 11 a.m. to 1 p.m., in front of Building 549 or in the Café Room, depending on the weather.

  4. Equestrian cold panniculitis in women.

    PubMed

    Beacham, B E; Cooper, P H; Buchanan, C S; Weary, P E

    1980-09-01

    We describe four patients with panniculitis attributable to a combination of cold exposure and equestrian activities. All were young, healthy women who rode horses for at least two consecutive hours per day throughout the winter. Initially, several small, erythematosus, pruritic papules appeared on the superior-lateral portions of one or both thighs. During one week, the lesions progressed to indurated, red-to-violaceous,tender plaques and nodules. Studies for cryofibrinogens and cryoglobulins were negative. The histologic picture was that of a panniculitis with prominent inflammation of veins most notable at the dermal-subcutaneus fat junction. Cold panniculitis is not limited to infancy and childhood. The distribution of lesions in our patients may have been caused, in part, by the use of tight-fitting, uninsulated riding pants. Such attire may have slowed blood flow through the skin, thereby further reducing tissue temperature. PMID:7191239

  5. Winter Cardiovascular Diseases Phenomenon

    PubMed Central

    Fares, Auda

    2013-01-01

    This paper review seasonal patterns across twelve cardiovascular diseases: Deep venous thrombosis, pulmonary embolism, aortic dissection and rupture, stroke, intracerebral hemorrhage, hypertension, heart failure, angina pectoris, myocardial infarction, sudden cardiac death, venricular arrythmia and atrial fibrillation, and discuss a possible cause of the occurrence of these diseases. There is a clear seasonal trend of cardiovascular diseases, with the highest incidence occurring during the colder winter months, which have been described in many countries. This phenomenon likely contributes to the numbers of deaths occurring in winter. The implications of this finding are important for testing the relative importance of the proposed mechanisms. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures. PMID:23724401

  6. Winter Wilderness Travel and Camping.

    ERIC Educational Resources Information Center

    Gilchrest, Norman

    Knowledge and skill are needed for safe and enjoyable travel and camping in the wilderness in winter. The beauty of snow and ice, reduced human use, and higher tolerance of animals toward humans make the wilderness attractive during winter. The uniqueness of winter travel presents several challenges that are not present in other seasons. Safety is…

  7. COLD TRAPS

    DOEpatents

    Thompson, W.I.

    1958-09-30

    A cold trap is presented for removing a condensable component from a gas mixture by cooling. It consists of a shell, the exterior surface of which is chilled by a refrigerant, and conductive fins welded inside the shell to condense the gas, and distribute the condensate evenly throughout the length of the trap, so that the trap may function until it becomes completely filled with the condensed solid. The contents may then be removed as either a gas or as a liquid by heating the trap. This device has particuinr use as a means for removing uranium hexafluoride from the gaseous diffusion separation process during equipment breakdown and repair periods.

  8. Some Chinese folk prescriptions for wind-cold type common cold

    PubMed Central

    Hai-long, Zhai; Shimin, Chen; Yalan, Lu

    2015-01-01

    Although self-limiting, the common cold (感冒gǎn mào) is highly prevalent. There are no effective antivirals to cure the common cold and few effective measures to prevent it, However, for thousands years, Chinese people have treated the common cold with natural herbs, According to the traditional Chinese medicine (TCM) theory (中醫理論 zhōng yī lǐ lùn), the common cold is considered as an exterior syndrome, which can be further divided into the wind-cold type (風寒型 fēng hán xíng), the wind-heat type (風熱型 fēng rè xíng), and the summer heat dampness type (暑熱型 shǔ rè xíng). Since the most common type of common cold caught in winter and spring is the wind-cold type, the article introduced some Chinese folk prescriptions for the wind-cold type common cold with normal and weak physique, respectively. For thousands of years, Chinese folk prescriptions for the common cold, as complementary and alternative medicine (CAM; 補充與替代醫學 bǔ chōng yǔ tì dài yī xué), have been proven to be effective, convenient, cheap, and most importantly, safe. The Chinese folk prescriptions (中國民間處方 zhōng guó mín jiān chǔ fāng) for the wind-cold type common cold are quite suitable for general practitioners or patients with the wind-cold type common cold, to treat the disease. Of course, their pharmacological features and mechanisms of action need to be further studied. PMID:26151024

  9. FACILITY 209, SINGLESTORY DUPLEX, FRONT OBLIQUE VIEW OF FRONT FROM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 209, SINGLE-STORY DUPLEX, FRONT OBLIQUE VIEW OF FRONT FROM CENTER DRIVE, FACING SW. - U.S. Naval Base, Pearl Harbor, Housing Area 1, Single Story Duplex Type, Bounded by Kamehameha Highway, Plantation Drive, South Avenue, Pearl City, Honolulu County, HI

  10. FACILITY 1042. FRONT OBLIQUE SHOWING ROYAL PALMS LINING FRONT WALK. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 1042. FRONT OBLIQUE SHOWING ROYAL PALMS LINING FRONT WALK. VIEW FACING SOUTHEAST - U.S. Naval Base, Pearl Harbor, Naval Housing Area Hale Alii, Junior Officers' Quarters Type, 9-10 Hale Alii Avenue, 1-2 Eighth Street, Pearl City, Honolulu County, HI

  11. Role of surface heat fluxes underneath cold pools

    NASA Astrophysics Data System (ADS)

    Gentine, Pierre; Garelli, Alix; Park, Seung-Bu; Nie, Ji; Torri, Giuseppe; Kuang, Zhiming

    2016-01-01

    The role of surface heat fluxes underneath cold pools is investigated using cloud-resolving simulations with either interactive or horizontally homogenous surface heat fluxes over an ocean and a simplified land surface. Over the ocean, there are limited changes in the distribution of the cold pool temperature, humidity, and gust front velocity, yet interactive heat fluxes induce more cold pools, which are smaller, and convection is then less organized. Correspondingly, the updraft mass flux and lateral entrainment are modified. Over the land surface, the heat fluxes underneath cold pools drastically impact the cold pool characteristics with more numerous and smaller pools, which are warmer and more humid and accompanied by smaller gust front velocities. The interactive fluxes also modify the updraft mass flux and reduce convective organization. These results emphasize the importance of interactive surface fluxes instead of prescribed flux boundary conditions, as well as the formulation of surface heat fluxes, when studying convection.

  12. Role of surface heat fluxes underneath cold pools

    PubMed Central

    Garelli, Alix; Park, Seung‐Bu; Nie, Ji; Torri, Giuseppe; Kuang, Zhiming

    2016-01-01

    Abstract The role of surface heat fluxes underneath cold pools is investigated using cloud‐resolving simulations with either interactive or horizontally homogenous surface heat fluxes over an ocean and a simplified land surface. Over the ocean, there are limited changes in the distribution of the cold pool temperature, humidity, and gust front velocity, yet interactive heat fluxes induce more cold pools, which are smaller, and convection is then less organized. Correspondingly, the updraft mass flux and lateral entrainment are modified. Over the land surface, the heat fluxes underneath cold pools drastically impact the cold pool characteristics with more numerous and smaller pools, which are warmer and more humid and accompanied by smaller gust front velocities. The interactive fluxes also modify the updraft mass flux and reduce convective organization. These results emphasize the importance of interactive surface fluxes instead of prescribed flux boundary conditions, as well as the formulation of surface heat fluxes, when studying convection. PMID:27134320

  13. Study of a Wind Front over the Northern South China Sea Generated by the Freshening of the North-East Monsoon

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Wong, Wai Kin; Dagestad, Knut-Frode; Chan, Pak Wai

    2015-10-01

    Wind fronts associated with cold-air outbreaks from the Chinese continent in the winter are often observed over the northern South China Sea and are well studied. However, wind fronts caused by another type of synoptic setting, the sudden increase or freshening of the north-east monsoon, which is caused by the merging of two anticyclonic regions over the Chinese continent, are also frequently encountered over the northern South China Sea. For the first time, such an event is investigated using multi-sensor satellite data, weather radar images, and a high-resolution atmospheric numerical model. It is shown that the wind front generated by the freshening of the north-east monsoon is quite similar to wind fronts generated by cold-air outbreaks. Furthermore, we investigate fine-scale features of the wind front that are visible on synthetic aperture radar (SAR) images through variations of the small-scale sea-surface roughness. The SAR image was acquired by the Advanced SAR of the European Envisat satellite over the South China Sea off the coast of Hong Kong and has a resolution of 150 m. It shows notches (dents) in the frontal line and also radar signatures of embedded rain cells. This (rare) SAR image, together with a quasi-simultaneously acquired weather radar image, provide excellent data with which to test the performance of the pre-operational version of the Atmospheric Integrated Rapid-cycle (AIR) forecast model system of the Hong Kong Observatory with respect to modelling rain cells at frontal boundaries. The calculations using a horizontal resolution with 3-km resolution show that the model reproduces quite well the position of the notches where rain cells are generated. The model shows further that at the position of the notches the vorticity of the airflow is increased leading to the uplift of warmer, moister air from the sea-surface to higher levels. With respect to the 10-km resolution model, the comparison of model data with the near-surface wind field

  14. Surface properties of ocean fronts

    NASA Technical Reports Server (NTRS)

    Wolff, P. M.; Hubert, W. E.

    1976-01-01

    Background information on oceanic fronts is presented and the results of several models which were developed to study the dynamics of oceanic fronts and their effects on various surface properties are described. The details of the four numerical models used in these studies are given in separate appendices which contain all of the physical equations, program documentation and running instructions for the models.

  15. MMS Observations of Dipolarization Fronts

    NASA Astrophysics Data System (ADS)

    Hwang, K. J.; Goldstein, M. L.; Sibeck, D. G.; Ashour-Abdalla, M.; Nakamura, R.; Burch, J. L.; Torbert, R. B.; Moore, T. E.; Ergun, R. E.; Pollock, C. J.; Mauk, B.; Fuselier, S. A.

    2015-12-01

    We present MMS observations of dipolarization fronts. Dipolarization fronts commonly observed in Earth's plasma sheet are characterized by intense gradients in the current sheet-normal component of the magnetic field and plasma/magnetic pressure across the front. These fronts are often embedded within fast earthward flows, i.e., bursty bulk flows. Analysis using data from all four spacecraft shows the presence of both typical and atypical dipolarization fronts. Typically dipolarization fronts propagate earthward and their normals point radially inward, however, we have identified dipolarization fronts propagating tailward with normals pointing significantly away from the radial direction. Atypical dipolarization fronts observed on 7 May 2015 and 21 July 2015 are preceded or accompanied by a rapid decrease in the Bx or By components of the magnetic field. These decreases indicate that the magnetotail is first thinning and then thickening. The resulting magnetic pile-up can cause the local Bz to increase rapidly, indicating propagation tailward, as observed. These new high time resolution field and plasma observations from MMS provide exciting new insights about the dynamical changes of magnetotail topology.

  16. Experimental Winter Coccidiosis in Sheltered and Unsheltered Calves

    PubMed Central

    Niilo, L.

    1970-01-01

    Hereford calves, seven months old, were inoculated orally with sporulated oocysts of Eimeria bovis and E. zurnii and housed in a heated building together with uninoculated animals. Duplicate groups of similarly treated animals were left unsheltered in cold winter weather. Clinical coccidiosis developed in most of the inoculated calves, sheltered and unsheltered. There was no marked difference in the severity of the infections. The sheltered uninoculated contact animals remained clinically unaffected, but mild coccidiosis developed in the unsheltered controls. The results suggest that cold may increase the host's susceptibility to clinical coccidiosis, but may not increase the severity of the signs once the clinical infection is established. PMID:4245999

  17. Identifying Lagrangian fronts with favourable fishery conditions

    NASA Astrophysics Data System (ADS)

    Prants, S. V.; Budyansky, M. V.; Uleysky, M. Yu.

    2014-08-01

    Lagrangian fronts (LFs) in the ocean are defined as boundaries between surface waters with strongly different Lagrangian properties. They can be accurately detected in a given velocity field by computing synoptic maps for displacements of synthetic tracers and other Lagrangian indicators. We use Pacific saury catch and location data for a number of commercial fishery seasons in the region of the northwest Pacific with one of the richest fishery in the world. It is shown statistically that the saury fishing grounds with maximal catches are not randomly distributed over the region but located mainly along the sharp LFs where productive cold waters of the Oyashio Current, warmer waters of the southern branch of the Soya Current, and waters of warm-core Kuroshio rings converge. Computation of those fronts in altimetric geostrophic velocity fields both in the years with the First and Second Oyashio Intrusions shows that in spite of different oceanographic conditions LF locations may serve as good indicators of potential fishing grounds. Possible biophysical reasons for saury aggregation near sharp LFs are discussed. We propose a mechanism for effective export of nutrient rich waters based on stretching of material lines in the vicinity of hyperbolic objects in the ocean. The developed method, based on identifying LFs in any velocity fields, is quite general and may be applied to find potential fishing grounds for the other pelagic fish.

  18. Winter Frost and Fog

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog.

    Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

  19. Assessment of cold stress in outdoor work.

    PubMed

    Anttonen, H; Virokannas, H

    1994-01-01

    The evaluation of cold stress in working life was done in 13, mainly outdoor, occupations and 143 workers using local temperatures, body cooling and thermal sensations. The subjects in the study were young, healthy men and they wore the type of winter clothing generally used in those ambient temperatures (+6...-29 degrees C), for in a work load of from 112 to 480 W. Local temperatures on finger skin indicated that manual dexterity was often reduced in outdoor work. A risk of frostbite was frequently found on the cheek and the wind chill index predicted the risk quite well. Body cooling was often temporarily too high when measured by heat debt and mean skin temperature. Thermal sensations were cool or cold occasionally in 28% of the workers interviewed. The insulation of clothing worn was often lower than the IREQmin-value recommends. The results showed that in outdoor work in winter time cold stress frequently reduced (70%) working ability at least for a short period. Mean skin temperature seems to be, in practice, a useful indicator for body cooling and the IREQmin-value was suitable, especially in light work, to indicate body cooling. A very sensitive factor for the expression of cold stress was finger temperature, at least as an indicator of finger dexterity. Due to the adverse health effects found the cold stress should also be evaluated more systematically in occupational health and safety with health examinations, with protective clothing and technical preventive means. PMID:8049001

  20. Model and observational analysis of the Northeast's regional winter climate and its relationship to the PNA pattern

    NASA Astrophysics Data System (ADS)

    Notaro, Michael

    A study was performed of the winter climate in the Northeast United States and its relationship to the large-scale circulation. Temperature, radiation, precipitation, and circulation features of the La Nina winter of 1998--1999 were analyzed through observations, NCEP-NCAR Reanalysis, and model simulations by SUNYA regional climate model (RCM). The relationship between the Pacific North American (PNA) pattern and regional winter climate of the Northeast was also investigated. Ten Decembers during the 1980s and 1990s were simulated, five with the most positive and five with the most negative PNA index. RCM reproduced the key climate features of the Northeast during the winter of 1998--1999. The model's circulation closely agreed with the reanalysis, particularly in the mid- and upper-troposphere, and with surface wind observations. Spatial and temporal patterns of temperature and precipitation agreed well with observations, despite a cold bias in the boundary layer (2--3°C) and dry bias in precipitation. The use of six-hourly, rather than twelve-hourly, reanalysis boundary conditions improved the diurnal cycle and increased the success at capturing fast-moving systems, such as fronts, and reproducing hourly weather variations. The relationship of the PNA pattern, and other teleconnection patterns, to the Northeast winter climate was investigated. Positive PNA pattern was associated with a stronger, southeastward shifted jet and colder, drier conditions in the Northeast, while mild surface southerlies were more frequent with negative PNA pattern. In the positive PNA simulations, there was a large air-water thermal gradient over the Great Lakes, enhancing evaporation and fluxes of sensible and latent heat. Precipitation and clouds during positive PNA pattern were less abundant across the domain, although lake-effect maxima were well defined. The PDO (Pacific Decadal Oscillation), PNA, and ENSO (El Nino/Southern Oscillation) teleconnections significantly influenced

  1. Cover Crop Biomass and Corn Yield Following 13 Rye, Wheat, and Triticale Cultivars Used as Winter Cover Crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter cover crops have the potential to reduce nitrate leaching and erosion in corn-soybean rotations in the upper Midwest. The cover crop growing season between harvest and planting of corn and soybean, however, is short and cold. Additionally, previous studies in Iowa have indicated that winter r...

  2. Field efficacy of wintertime insecticide applications against greenbugs, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), on winter wheat (Triticum aestivum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter wheat producers in Oklahoma often combine an insecticide with a top-dress application of nitrogen during late fall or winter to control existing greenbug populations. We evaluated the efficacy of three classes of insecticides applied in cold weather conditions ranging from -13.3 degrees to 2...

  3. Spirit's Winter Work Site

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Annotated Version

    This portion of an image acquired by the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment camera shows the Spirit rover's winter campaign site. Spirit was parked on a slope tilted 11 degrees to the north to maximize sunlight during the southern winter season. 'Tyrone' is an area where the rover's wheels disturbed light-toned soils. Remote sensing and in-situ analyses found the light-toned soil at Tyrone to be sulfate rich and hydrated. The original picture is catalogued as PSP_001513_1655_red and was taken on Sept. 29, 2006.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

  4. Cough & Cold Medicine Abuse

    MedlinePlus

    ... I Help a Friend Who Cuts? Cough & Cold Medicine Abuse KidsHealth > For Teens > Cough & Cold Medicine Abuse ... DXM Why Do People Use Cough and Cold Medicines to Get High? There's an ingredient in many ...

  5. Cold symptoms (image)

    MedlinePlus

    Colds are caused by a virus and can occur year-round. The common cold generally involves a runny nose, nasal congestion, and ... symptoms include sore throat, cough, and headache. A cold usually lasts about 7 days, with perhaps a ...

  6. Colds and flus - antibiotics

    MedlinePlus

    Antibiotics - colds and flu ... treat infections that are caused by a virus. Colds and flu are caused by viruses. If you ... Hamilton A. Treatments for symptoms of the common cold. Am Fam Physician. 2013;88(12):Online. PMID: ...

  7. Vitamin C and colds

    MedlinePlus

    Colds and vitamin C ... belief that vitamin C can cure the common cold , research about this claim is conflicting. Large doses ... vitamin C may help reduce how long a cold lasts, but they do not appear to protect ...

  8. Winter Lake Breezes near the Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Crosman, Erik T.; Horel, John D.

    2016-05-01

    Case studies of lake breezes during wintertime cold air pools in Utah's Salt Lake Valley are examined. While summer breezes originating from the Great Salt Lake are typically deeper, of longer duration, and have higher wind speeds than winter breezes, the rate of inland penetration and cross-frontal temperature differences can be higher during the winter. The characteristics of winter breezes and the forcing mechanisms controlling them (e.g., snow cover, background flow, vertical stability profile, clouds, lake temperature, lake sheltering, and drainage pooling) are more complex and variable than those evident in summer. During the afternoon in the Salt Lake Valley, these lake breezes can lead to elevated pollution levels due to the transport of fine particle pollutants from over the Great Salt Lake, decreased vertical mixing depth, and increased vertical stability.

  9. Flame front as hydrodynamic discontinuity

    NASA Astrophysics Data System (ADS)

    Fukumoto, Yasuhide; Abarzhi, Snezhana

    2012-11-01

    We applied generalized Rankine-Hugoniot conditions to study the dynamics of unsteady and curved fronts as a hydrodynamic discontinuity. It is shown that the front is unstable and Landau-Darrieus instability develops only if three conditions are satisfied (1) large-scale vorticity is generated in the fluid bulk; (2) energy flux across the front is imbalanced; (3) the energy imbalance is large. The structure of the solution is studied in details. Flows with and without gravity and thermal diffusion are analyzed. Stabilization mechanisms are identified. NSF 1004330.

  10. Asymmetric counterpropagating fronts without flow.

    PubMed

    Andrade-Silva, I; Clerc, M G; Odent, V

    2015-06-01

    Out-of-equilibrium systems exhibit domain walls between different states. These walls, depending on the type of connected states, can display rich spatiotemporal dynamics. In this Rapid Communication, we investigate the asymmetrical counterpropagation of fronts in an in-plane-switching cell filled with a nematic liquid crystal. Experimentally, we characterize the different front shapes and propagation speeds. These fronts present dissimilar elastic deformations that are responsible for their asymmetric speeds. Theoretically, using a phenomenological model, we describe the observed dynamics with fair agreement. PMID:26172647

  11. a Climatology of Extreme Minimum Winter Temperatures in Ohio

    NASA Astrophysics Data System (ADS)

    Edgell, Dennis Joe

    The Extreme Minimum Winter Temperature (EMWT) is the coldest temperature recorded each winter at a given weather station. This variable is a measure of winter temperature stress. Extreme cold influences the geographic distribution of plants, and is a prime control for the production of some valuable fruit crops grown in Ohio. EMWT values are often used to map plant hardiness zones, however the magnitude of EMWT and the date that it occurs has varied widely from year to year. Climatic variables rarely remain constant over time, and the plant hardiness zones could shift significantly if the climate changes and there is a trend towards warmer EMWTs. Plants that have their present geographic ranges limited by cold winter temperatures could increase their spatial extent. Furthermore, EMWT has impacts on human health and has applications for architecture. EMWTs at eighty-nine weather stations in Ohio were analyzed. Summary statistics and return period intervals for critical EMWTs are tabulated and mapped. Return period maps may be more useful for environmental planning than plant hardiness zone maps based on average EMWT, especially in a variable climate. Graphical methods, curve fitting and a probability model for the mean were utilized to examine the long term trend. The EMWT has not warmed during the known climatic record of this variable in Ohio. This study demonstrates the need for more applied climatological studies based on the observed climate record, not obscured by the assumptions of the global warming paradigm.

  12. Is the OJIP Test a Reliable Indicator of Winter Hardiness and Freezing Tolerance of Common Wheat and Triticale under Variable Winter Environments?

    PubMed Central

    Rapacz, Marcin; Sasal, Monika; Kalaji, Hazem M.; Kościelniak, Janusz

    2015-01-01

    OJIP analysis, which explores changes in photosystem II (PSII) photochemical performance, has been used as a measure of plant susceptibility to stress. However, in the case of freezing tolerance and winter hardiness, which are highly environmentally variable, the use of this method can give ambiguous results depending on the species as well as the sampling year and time. To clarify this issue, we performed chlorophyll fluorescence measurements over three subsequent winters (2010/11, 2011/12 and 2012/13) on 220 accessions of common winter wheat and 139 accessions of winter triticale. After freezing, leaves were collected from cold-acclimated plants in the laboratory and field-grown plants. Observations of field survival in seven locations across Poland and measurements of freezing tolerance of the studied plants were also recorded. Our results confirm that the OJIP test is a reliable indicator of winter hardiness and freezing tolerance of common wheat and triticale under unstable winter environments. Regardless of species, the testing conditions giving the most reliable results were identical, and the reliability of the test could be easily checked by analysis of some relationships between OJIP-test parameters. We also found that triticale is more winter hardy and freezing tolerant than wheat. In addition, the two species were characterized by different patterns of photosynthetic apparatus acclimation to cold. PMID:26230839

  13. Cold Atoms

    NASA Astrophysics Data System (ADS)

    Bellac, Michel Le

    2014-11-01

    This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

  14. INSTABILITY OF MAGNETIZED IONIZATION FRONTS SURROUNDING H II REGIONS

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2014-12-20

    An ionization front (IF) surrounding an H II region is a sharp interface where a cold neutral gas makes the transition to a warm ionized phase by absorbing UV photons from central stars. We investigate the instability of a plane-parallel D-type IF threaded by parallel magnetic fields, by neglecting the effects of recombination within the ionized gas. We find that weak D-type IFs always have the post-IF magnetosonic Mach number M{sub M2}≤1. For such fronts, magnetic fields increase the maximum propagation speed of the IFs, while reducing the expansion factor α by a factor of 1 + 1/(2β{sub 1}) compared to the unmagnetized case, with β{sub 1} denoting the plasma beta in the pre-IF region. IFs become unstable to distortional perturbations owing to gas expansion across the fronts, exactly analogous to the Darrieus-Landau instability of ablation fronts in terrestrial flames. The growth rate of the IF instability is proportional linearly to the perturbation wavenumber, as well as the upstream flow speed, and approximately to α{sup 1/2}. The IF instability is stabilized by gas compressibility and becomes completely quenched when the front is D-critical. The instability is also stabilized by magnetic pressure when the perturbations propagate in the direction perpendicular to the fields. When the perturbations propagate in the direction parallel to the fields, on the other hand, it is magnetic tension that reduces the growth rate, completely suppressing the instability when M{sub M2}{sup 2}<2/(2β{sub 1}−1). When the front experiences an acceleration, the IF instability cooperates with the Rayleigh-Taylor instability to make the front more unstable.

  15. Predictability of winter temperature in China from previous autumn Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Zuo, Jinqing; Ren, Hong-Li; Wu, Bingyi; Li, Weijing

    2016-01-01

    The potential predictability of winter temperature in China from autumn Arctic sea ice anomalies is studied by examining and statistically modeling the large-scale interannual covariability between them on the basis of singular value decomposition analysis. It is demonstrated that an intimate relationship exists between September and October sea ice anomalies in the Eurasian Arctic and following winter temperature anomalies in China, except in the Tibetan Plateau. When the autumn sea ice anomalies decline in the Eurasian Arctic, above-normal pressure anomalies appear to prevail over the region from the Eurasian Arctic to Eastern Europe and Mongolia, and below-normal anomalies prevail over the mid-latitudes of Asia and Northwestern Pacific in the following winter. Consequently, the winter Siberian High and East Asian trough are both strengthened, favoring the southward invasion of high-latitude cold air masses and thus cold temperature anomalies in China. It is found that the Siberian High plays a crucial role in delivering effects of the autumn Arctic sea ice anomalies on winter temperature variability in China. Based on this evidence, a statistical model is established to examine the potential predictability of winter temperature anomalies in China by taking the autumn Arctic sea ice signals as a predictor. Validation shows considerable skill in predicting winter temperature anomalies over a large part of China, indicating a significant potential for improving winter climate prediction in China.

  16. Winter fuels report

    SciTech Connect

    Not Available

    1990-11-29

    The Winter Fuels Report is intended to provide concise, timely information to the industry, the press, policymakers, consumers, analysts, and state and local governments on the following topics: distillate fuel oil net production, imports and stocks for all PADD's and product supplied on a US level; propane net product supplied on a US level; propane net production, imports and stocks for Petroleum Administration for Defense Districts (PADD) I, II, and III; natural gas supply and disposition and underground storage for the United States and consumption for all PADD's; residential and wholesale pricing data for propane and heating oil for those states participating in the joint Energy Information Administration (EIA)/State Heating Oil and Propane Program; crude oil and petroleum price comparisons for the United States and selected cities; and US total heating degree-days by city. 27 figs, 12 tabs.

  17. Winter weather scorecard

    NASA Astrophysics Data System (ADS)

    Last fall's 3-month winter weather prediction by National Weather Service (NWS) forecasters was not terrific, but it was not too far off the mark, either. A comparison of the predicted temperatures and precipitation (Eos, December 25, 1984, p. 1241) to the observed conditions (see Figures 1 and 2) during the months of December, January, and February shows that the forecasters were generally correct where they were most confident in their predictions.According to Donald Gilman, chief of the Predictions Branch at NWS's National Climate Analysis Center, the overall temperature forecast was probably better than that for precipitation. “The temperature forecast was pretty good in the West,” said Gilman. “East of the Mississippi, however, was a mixed picture.”

  18. Spirit Scans Winter Haven

    NASA Technical Reports Server (NTRS)

    2006-01-01

    At least three different kinds of rocks await scientific analysis at the place where NASA's Mars Exploration Rover Spirit will likely spend several months of Martian winter. They are visible in this picture, which the panoramic camera on Spirit acquired during the rover's 809th sol, or Martian day, of exploring Mars (April 12, 2006). Paper-thin layers of light-toned, jagged-edged rocks protrude horizontally from beneath small sand drifts; a light gray rock with smooth, rounded edges sits atop the sand drifts; and several dark gray to black, angular rocks with vesicles (small holes) typical of hardened lava lie scattered across the sand.

    This view is an approximately true-color rendering that combines images taken through the panoramic camera's 753-nanometer, 535-nanometer, and 432-nanometer filters.

  19. The ABCs of Front Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Frost protection or protecting plants from cold temperatures where they could be damaged must be a major consideration in orchard planning. Cold temperature protection events commonly occur during "radiation" frost conditions when the sky is clear, there is little wind and temperature inversions ca...

  20. Winter Survival: A Consumer's Guide to Winter Preparedness.

    ERIC Educational Resources Information Center

    Department of Energy, Washington, DC.

    This booklet discusses a variety of topics to help consumers prepare for winter. Tips for the home include: winterizing the home, dealing with a loss of heat or power failure, and what you need to have on hand. Another section gives driving tips and what to do in a storm. Health factors include suggestions for keeping warm, signs and treatment for…

  1. Beyond arctic and alpine: the influence of winter climate on temperate ecosystems.

    PubMed

    Ladwig, Laura M; Ratajczak, Zak R; Ocheltree, Troy W; Hafich, Katya A; Churchill, Amber C; Frey, Sarah J K; Fuss, Colin B; Kazanski, Clare E; Muñoz, Juan D; Petrie, Matthew D; Reinmann, Andrew B; Smith, Jane G

    2016-02-01

    Winter climate is expected to change under future climate scenarios, yet the majority of winter ecology research is focused in cold-climate ecosystems. In many temperate systems, it is unclear how winter climate relates to biotic responses during the growing season. The objective of this study was to examine how winter weather relates to plant and animal communities in a variety of terrestrial ecosystems ranging from warm deserts to alpine tundra. Specifically, we examined the association between winter weather and plant phenology, plant species richness, consumer abundance, and consumer richness in 11 terrestrial ecosystems associated with the U.S. Long-Term Ecological Research (LTER) Network. To varying degrees, winter precipitation and temperature were correlated with all biotic response variables. Bud break was tightly aligned with end of winter temperatures. For half the sites, winter weather was a better predictor of plant species richness than growing season weather. Warmer winters were correlated with lower consumer abundances in both temperate and alpine systems. Our findings suggest winter weather may have a strong influence on biotic activity during the growing season and should be considered in future studies investigating the effects of climate change on both alpine and temperate systems. PMID:27145612

  2. Expansion of a cold non-neutral plasma slab

    SciTech Connect

    Karimov, A. R.; Yu, M. Y.; Stenflo, L.

    2014-12-15

    Expansion of the ion and electron fronts of a cold non-neutral plasma slab with a quasi-neutral core bounded by layers containing only ions is investigated analytically and exact solutions are obtained. It is found that on average, the plasma expansion time scales linearly with the initial inverse ion plasma frequency as well as the degree of charge imbalance, and no expansion occurs if the cold plasma slab is stationary and overall neutral. However, in both cases, there can exist prominent oscillations on the electron front.

  3. Cold energy

    SciTech Connect

    Wallace, John P.

    2015-12-04

    Deviations in Q for resonant superconducting radio frequency niobium accelerator cavities are generally correlated with resistivity loss mechanisms. Field dependent Qs are not well modeled by these classical loss mechanisms, but rather can represent a form of precision cavity surface thermometry. When the field dependent Q variation shows improvement with increasing B field level the classical treatment of this problem is inadequate. To justify this behavior hydrogen as a ubiquitous impurity in niobium, which creates measurable property changes, even at very low concentrations is typically considered the cause of such anomalous behavior. This maybe the case in some instances, but more importantly any system operating with a highly coherent field with a significant time dependent magnetic component at near 2° K will have the ability to organize the remaining free spins within the London penetration depth to form a coupled energy reservoir in the form of low mass spin waves. The niobium resonant cavities are composed of a single isotope with a large nuclear spin. When the other loss mechanisms are stripped away this may be the gain medium activated by the low level residual magnetic fields. It was found that one resonant cavity heat treatment produced optimum surface properties and then functioned as a MASER extracting energy from the 2° K thermal bath while cooling the cavity walls. The cavity operating in this mode is a simulator of what can take place in the wider but not colder universe using the cosmic microwave background (CMB) as a thermal source. The low mass, long lifetimes, and the scale of the magnetic spin waves on the weakly magnetized interstellar medium allows energy to be stored that is many orders of magnitude colder than the cosmic microwave background. A linear accelerator cavity becomes a tool to explore the properties of the long wave length magnetic spin waves that populate this cold low energy regime.

  4. Cold energy

    NASA Astrophysics Data System (ADS)

    Wallace, John P.

    2015-12-01

    Deviations in Q for resonant superconducting radio frequency niobium accelerator cavities are generally correlated with resistivity loss mechanisms. Field dependent Qs are not well modeled by these classical loss mechanisms, but rather can represent a form of precision cavity surface thermometry. When the field dependent Q variation shows improvement with increasing B field level the classical treatment of this problem is inadequate. To justify this behavior hydrogen as a ubiquitous impurity in niobium, which creates measurable property changes, even at very low concentrations is typically considered the cause of such anomalous behavior. This maybe the case in some instances, but more importantly any system operating with a highly coherent field with a significant time dependent magnetic component at near 2° K will have the ability to organize the remaining free spins within the London penetration depth to form a coupled energy reservoir in the form of low mass spin waves. The niobium resonant cavities are composed of a single isotope with a large nuclear spin. When the other loss mechanisms are stripped away this may be the gain medium activated by the low level residual magnetic fields. It was found that one resonant cavity heat treatment produced optimum surface properties and then functioned as a MASER extracting energy from the 2° K thermal bath while cooling the cavity walls. The cavity operating in this mode is a simulator of what can take place in the wider but not colder universe using the cosmic microwave background (CMB) as a thermal source. The low mass, long lifetimes, and the scale of the magnetic spin waves on the weakly magnetized interstellar medium allows energy to be stored that is many orders of magnitude colder than the cosmic microwave background. A linear accelerator cavity becomes a tool to explore the properties of the long wave length magnetic spin waves that populate this cold low energy regime.

  5. Restless rays, steady wave fronts.

    PubMed

    Godin, Oleg A

    2007-12-01

    Observations of underwater acoustic fields with vertical line arrays and numerical simulations of long-range sound propagation in an ocean perturbed by internal gravity waves indicate that acoustic wave fronts are much more stable than the rays comprising these wave fronts. This paper provides a theoretical explanation of the phenomenon of wave front stability in a medium with weak sound-speed perturbations. It is shown analytically that at propagation ranges that are large compared to the correlation length of the sound-speed perturbations but smaller than ranges at which ray chaos develops, end points of rays launched from a point source and having a given travel time are scattered primarily along the wave front corresponding to the same travel time in the unperturbed environment. The ratio of root mean square displacements of the ray end points along and across the unperturbed wave front increases with range as the ratio of ray length to correlation length of environmental perturbations. An intuitive physical explanation of the theoretical results is proposed. The relative stability of wave fronts compared to rays is shown to follow from Fermat's principle and dimensional considerations. PMID:18247745

  6. Observed Variability and Trends In Winter Extreme Minimum in Turkey, From 1966-2014

    NASA Astrophysics Data System (ADS)

    Acar Deniz, Zahide; Gonencgil, Barbaros

    2016-04-01

    Knowledge of extreme temperature events is consequential physical effects. Cold and hot events have delimitated activity of human and quality of life. In this study, winter temperature extremes and their spatiotemporal variability are investigated at 156 meteorological stations in Turkey. We have chosen the following two indices of extremes; frequency of days with minimum temperature below the 1966-2014 mean 1st (extreme cold nights) and 5th (cold nights) percentiles. Trends in extreme minimum temperature have been analyzed from 1966 to 2014 in winter season. In order to detect possible trends in extreme temperature over the Turkey, the Mann-Kendall test has applied to the annual percentile series. The lowest minimum temperature extreme values are observed in the east of Turkey. The most extreme cold events have been experienced in 1972. The Central and eastern regions of Turkey, be effective in the continental climate, there are increasing numbers of extreme cold night events. Extreme cold events are less observed in coastal stations. The number of extreme cold events has been observed a downward trend since 1990. The decreasing trends are not statistically significant. This situation displays cold events have fewer experienced from year to year. This study is supported by the Turkish Scientific and Technical Research Institute (Project number: 114Y417). Keywords: Extreme temperature, cold events, Mann-Kendall, Turkey.

  7. Evolution of a physical and biological front from upwelling to relaxation

    NASA Astrophysics Data System (ADS)

    Zhang, Yanwu; Bellingham, James G.; Ryan, John P.; Godin, Michael A.

    2015-10-01

    Fronts influence the structure and function of coastal marine ecosystems. Due to the complexity and dynamic nature of coastal environments and the small scales of frontal gradient zones, frontal research is difficult. To advance this challenging research we developed a method enabling an autonomous underwater vehicle (AUV) to detect and track fronts, thereby providing high-resolution observations in the moving reference frame of the front itself. This novel method was applied to studying the evolution of a frontal zone in the coastal upwelling environment of Monterey Bay, California, through a period of variability in upwelling intensity. Through 23 frontal crossings in four days, the AUV detected the front using real-time analysis of vertical thermal stratification to identify water types and the front between them, and the vehicle tracked the front as it moved more than 10 km offshore. The physical front coincided with a biological front between strongly stratified phytoplankton-enriched water inshore of the front, and weakly stratified phytoplankton-poor water offshore of the front. While stratification remained a consistent identifier, conditions on both sides of the front changed rapidly as regional circulation responded to relaxation of upwelling winds. The offshore water type transitioned from relatively cold and saline upwelled water to relatively warm and fresh coastal transition zone water. The inshore water type exhibited an order of magnitude increase in chlorophyll concentrations and an associated increase in oxygen and decrease in nitrate. It also warmed and freshened near the front, consistent with the cross-frontal exchange that was detected in the high-resolution AUV data. AUV-observed cross-frontal exchanges beneath the surface manifestation of the front emphasize the importance of AUV synoptic water column surveys in the frontal zone.

  8. Cold tolerance of the montane Sierra leaf beetle, Chrysomela aeneicollis.

    PubMed

    Boychuk, Evelyn C; Smiley, John T; Dahlhoff, Elizabeth P; Bernards, Mark A; Rank, Nathan E; Sinclair, Brent J

    2015-10-01

    Small ectothermic animals living at high altitude in temperate latitudes are vulnerable to lethal cold throughout the year. Here we investigated the cold tolerance of the leaf beetle Chrysomela aeneicollis living at high elevation in California's Sierra Nevada mountains. These insects spend over half their life cycle overwintering, and may therefore be vulnerable to winter cold, and prior studies have demonstrated that survival is reduced by exposure to summertime cold. We identify overwintering microhabitat of this insect, describe cold tolerance strategies in all life stages, and use microclimate data to determine the importance of snow cover and microhabitat buffering for overwinter survival. Cold tolerance varies among life history stages and is typically correlated with microhabitat temperature: cold hardiness is lowest in chill-susceptible larvae, and highest in freeze-tolerant adults. Hemolymph osmolality is higher in quiescent (overwintering) than summer adults, primarily, but not exclusively, due to elevated hemolymph glycerol. In nature, adult beetles overwinter primarily in leaf litter and suffer high mortality if early, unseasonable cold prevents them from entering this refuge. These data suggest that cold tolerance is tightly linked to life stage. Thus, population persistence of montane insects may become problematic as climate becomes more unpredictable and climate change uncouples the phenology of cold tolerance and development from the timing of extreme cold events. PMID:26231921

  9. Coastal dynamics off Northwest Iberia during a stormy winter period

    NASA Astrophysics Data System (ADS)

    Otero, Pablo; Ruiz-Villarreal, Manuel; García-García, Luz; González-Nuevo, Gonzalo; Cabanas, Jose Manuel

    2013-01-01

    The consequences of a stormy winter period (2009/2010) on the shelf and coastal dynamics off Northwest Iberia are analysed by using model results in combination with the set of available observations in the frame of the Iberian Margin Ocean Observatory (RAIA), a cross-border infrastructure among North Portugal and Galicia (Spain). During the study winter, the frequent arrival of weather fronts forced river plumes to flow along the inner shelf in a fast (>1 m s-1) jet-like structure. The buoyant current strongly influenced the outer rías, the name of the estuaries in the region, where a strong decay of surface salinity (<10.5) has been observed. Once the weather front has passed, the wind reversal forced the offshore expansion of river plumes and also the development of a winter upwelling event. Thermohaline patterns in both model and observations revealed an intrusion of warm (>15 °C) and salty (>35.9) waters into the rías associated with the Iberian Poleward Current. Finally, some Lagrangian modelling experiments were performed to analyse the transport ability of the plume and the effect that could have had in the biological material trapped on it. The experiments reveal that an overall northward displacement of surface particles will be expected after several alternate wind events.

  10. Spatial and temporal variation in daily temperature indices in summer and winter seasons over India (1969-2012)

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Jaswal, A. K.; Mohapatra, M.; Kore, P. A.

    2016-06-01

    Spatial and temporal variations in summer and winter extreme temperature indices are studied by using daily maximum and minimum temperatures data from 227 surface meteorological stations well distributed over India for the period 1969-2012. For this purpose, time series for six extreme temperature indices namely, hot days (HD), very hot days (VHD), extremely hot days (EHD), cold nights (CN), very cold nights (VCN), and extremely cold nights (ECN) are calculated for all the stations. In addition, time series for mean extreme temperature indices of summer and winter seasons are also analyzed. Study reveals high variability in spatial distribution of threshold temperatures of extreme temperature indices over the country. In general, increasing trends are observed in summer hot days indices and decreasing trends in winter cold night indices over most parts of the country. The results obtained in this study indicate warming in summer maximum and winter minimum temperatures over India. Averaged over India, trends in summer hot days indices HD, VHD, and EHD are significantly increasing (+1.0, +0.64, and +0.32 days/decade, respectively) and winter cold night indices CN, VCN, and ECN are significantly decreasing (-0.93, -0.47, and -0.15 days/decade, respectively). Also, it is observed that the impact of extreme temperature is higher along the west coast for summer and east coast for winter.

  11. The anomalous winter of 1783-1784: Was the Laki eruption or an analog of the 2009-2010 winter to blame?

    NASA Astrophysics Data System (ADS)

    D'Arrigo, Rosanne; Seager, Richard; Smerdon, Jason E.; LeGrande, Allegra N.; Cook, Edward R.

    2011-03-01

    The multi-stage eruption of the Icelandic volcano Laki beginning in June, 1783 is speculated to have caused unusual dry fog and heat in western Europe and cold in North America during the 1783 summer, and record cold and snow the subsequent winter across the circum-North Atlantic. Despite the many indisputable impacts of the Laki eruption, however, its effect on climate, particularly during the 1783-1784 winter, may be the most poorly constrained. Here we test an alternative explanation for the unusual conditions during this time: that they were caused primarily by a combined negative phase of the North Atlantic Oscillation (NAO) and an El Niño-Southern Oscillation (ENSO) warm event. A similar combination of NAO-ENSO phases was identified as the cause of record cold and snowy conditions during the 2009-2010 winter in Europe and eastern North America. 600-year tree-ring reconstructions of NAO and ENSO indices reveal values in the 1783-1784 winter second only to their combined severity in 2009-2010. Data sources and model simulations support our hypothesis that a combined, negative NAO-ENSO warm phase was the dominant cause of the anomalous winter of 1783-1784, and that these events likely resulted from natural variability unconnected to Laki.

  12. The Anomalous Winter of 1783-1784: Was the Laki Eruption or an Analog of the 2009-2010 Winter to Blame?

    NASA Technical Reports Server (NTRS)

    D'Arrigo, Rosanne; Seager, Richard; Smerdon, Jason E.; LeGrande, Allegra N.; Cook, Edward R.

    2011-01-01

    The multi ]stage eruption of the Icelandic volcano Laki beginning in June, 1783 is speculated to have caused unusual dry fog and heat in western Europe and cold in North America during the 1783 summer, and record cold and snow the subsequent winter across the circum-North Atlantic. Despite the many indisputable impacts of the Laki eruption, however, its effect on climate, particularly during the 1783.1784 winter, may be the most poorly constrained. Here we test an alternative explanation for the unusual conditions during this time: that they were caused primarily by a combined negative phase of the North Atlantic Oscillation (NAO) and an El Nino ]Southern Oscillation (ENSO) warm event. A similar combination of NAO ]ENSO phases was identified as the cause of record cold and snowy conditions during the 2009.2010 winter in Europe and eastern North America. 600-year tree-ring reconstructions of NAO and ENSO indices reveal values in the 1783.1784 winter second only to their combined severity in 2009.2010. Data sources and model simulations support our hypothesis that a combined, negative NAO ]ENSO warm phase was the dominant cause of the anomalous winter of 1783.1784, and that these events likely resulted from natural variability unconnected to Laki.

  13. Winter fuels report

    SciTech Connect

    Not Available

    1990-10-04

    The Winter Fuels Report is intended to provide concise, timely information to the industry, the press, policymakers, consumers, analysts, and state and local governments on the following topics: distillate fuel oil net production, imports and stocks for all PADD's and product supplied on a US level; propane net production, imports and stocks for Petroleum Administration for Defense Districts (PADD) I, II, and III; natural gas supply and disposition, underground storage, and consumption for all PADD's; residential and wholesale pricing data for propane and heating oil for those states participating in the joint Energy Information Administration (EIA)/State Heating Oil and Propane Program; crude oil price comparisons for the United States and selected cities; and US total heating degree-days by city. This report will be published weekly by the EIA starting the first week in October 1990 and will continue until the first week in April 1991. The data will also be available electronically after 5:00 p.m. on Thursday during the heating season through the EIA Electronic Publication System (EPUB). 12 tabs.

  14. Using synoptic classification and trajectory analysis to assess air quality during the winter heating period in Ürümqi, China

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Wang, Yuesi; Sun, Yang; Li, Yuanyuan

    2012-03-01

    Synoptic patterns identified by an automated procedure employing principal-component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine air quality patterns over Ürümqi, China, one of the most heavily polluted cities in the world. Six synoptic patterns representing different atmospheric circulation patterns and air-mass characteristics were classified during the winter heating periods from 2001 to 2008, and seven trajectory clusters representing different paths of air masses arriving at Ürümqi were calculated during the winter heating periods from 2005 to 2008. Then air quality was evaluated using these two approaches, and significant variations were found across both synoptic patterns and trajectory clusters. The heaviest air-pollution episodes occurred when Ürümqi was either in an extremely cold, strong anticyclone or at the front of a migrating cyclone. Both conditions were characterized by with light winds, cold, wet surface air, and relatively dry upper air. Ürümqi was predominately influenced by air masses from the southwest and from local areas. Air pollution index (API) levels were highest for air masses originating from the southwest with a longer path or for the local area, because of transport from semi-desert/desert regions by strong winds and because of local heavy pollution emissions, respectively. The interactions between these two analytical approaches showed that poor diffusion conditions, together with local circulation, enhanced air pollution, besides, regional air-mass transport caused by strong winds contributed to serious air quality under relatively good diffusion conditions.

  15. Self-turbulizing flame fronts

    NASA Astrophysics Data System (ADS)

    Clavin, P.; Searby, G.

    A heuristic derivation of a flame front model is presented that takes into account the effects of gravity, nonlinear effects introduced by advection of the front, and gradients in the tangential component of the flow. A local equation is defined to relate the normal flame speed to the upstream gas flow characteristics. Jump conditions are obtained from an asymptotic analysis of the local structure of the wrinkled flame in order to address the hydrodynamic problem possed by the front being treated as a free boundary between fresh and burnt gases. The expression for the jump conditions is defined in Fourier space. The model extends the equations defined in Fourier space. The model extends the equations defined by Sivashinsky (1977) to cover the effects of gas expansion.

  16. Eddy overturning of the Antarctic Slope Front controls glacial melting in the Eastern Weddell Sea

    NASA Astrophysics Data System (ADS)

    NøSt, O. A.; Biuw, M.; Tverberg, V.; Lydersen, C.; Hattermann, T.; Zhou, Q.; Smedsrud, L. H.; Kovacs, K. M.

    2011-11-01

    The Eastern Weddell Sea is characterized by narrow continental shelves and Warm Deep Water (WDW) is located in close proximity to the ice shelves in this region. The exchange of WDW across the Antarctic Slope Front (ASF) determines the rate of basal ice shelf melting. Here, we present a unique data set consisting of 2351 vertical profiles of temperature and salinity collected by southern elephant seals (Mirounga leonina) and a profile beneath the Fimbul Ice Shelf (FIS), obtained via drilling through 395 m of ice. This data set reveals variations in salinity and temperature through winter, and using a conceptual model of the coastal salt budget we quantify the main exchange processes. Our data show that modified WDW, with temperatures below -1.5°C, is advected onto the shelf and into the ice shelf cavities by an eddy overturning of the ASF. The onshore Ekman flux of surface waters during summer is the main source of freshwater that leads to the formation of low salinity shelf waters in the region. The modified WDW that reaches beneath the ice shelves is too cold for basal ice shelf melting to create such low salinity water. A high-resolution model of an idealized ASF-continental shelf-ice shelf system supports the conclusions from the data analysis. The inflow of WDW onto the continental shelf and into the ice shelf cavity occurs within a bottom boundary layer where the eddy advection in the model is particularly strong, in close agreement with the observed vertical profile of temperature beneath the FIS.

  17. Temperature characteristics of winter roost-sites for birds and mammals: tree cavities and anthropogenic alternatives

    NASA Astrophysics Data System (ADS)

    Grüebler, Martin U.; Widmer, Silv; Korner-Nievergelt, Fränzi; Naef-Daenzer, Beat

    2014-07-01

    The microclimate of potential roost-sites is likely to be a crucial determinant in the optimal roost-site selection of endotherms, in particular during the winter season of temperate zones. Available roost-sites for birds and mammals in European high trunk orchards are mainly tree cavities, wood stacks and artificial nest boxes. However, little is known about the microclimatic patterns inside cavities and thermal advantages of using these winter roost-sites. Here, we simultaneously investigate the thermal patterns of winter roost-sites in relation to winter ambient temperature and their insulation capacity. While tree cavities and wood stacks strongly buffered the daily cycle of temperature changes, nest boxes showed low buffering capacity. The buffering effect of tree cavities was stronger at extreme ambient temperatures compared to temperatures around zero. Heat sources inside roosts amplified Δ T (i.e., the difference between inside and outside temperatures), particularly in the closed roosts of nest boxes and tree cavities, and less in the open wood stacks with stronger circulation of air. Positive Δ T due to the installation of a heat source increased in cold ambient temperatures. These results suggest that orchard habitats in winter show a spatiotemporal mosaic of sites providing different thermal benefits varying over time and in relation to ambient temperatures. At cold temperatures tree cavities provide significantly higher thermal benefits than nest boxes or wood stacks. Thus, in winter ecology of hole-using endotherms, the availability of tree cavities may be an important characteristic of winter habitat quality.

  18. Projected changes to winter temperature characteristics over Canada based on an RCM ensemble

    NASA Astrophysics Data System (ADS)

    Jeong, Dae Il; Sushama, Laxmi; Diro, Gulilat Tefera; Khaliq, M. Naveed

    2015-11-01

    Cold temperature and associated extremes often impact adversely human health and environment and bring disruptions in economic activities during winter over Canada. This study investigates projected changes in winter (December to March) period cold extreme days (i.e., cold nights, cold days, frost days, and ice days) and cold spells over Canada based on 11 regional climate model (RCM) simulations for the future 2040-2069 period with respect to the current 1970-1999 period. These simulations, available from the North American Regional Climate Change Assessment Program, were obtained with six different RCMs, when driven by four different Atmosphere-Ocean General Circulation Models, under the Special Report on Emissions Scenarios A2 scenario. Based on the reanalysis boundary conditions, the RCM simulations reproduce spatial patterns of observed mean values of the daily minimum and maximum temperatures and inter-annual variability of the number of cold nights over different Canadian climatic regions considered in the study. A comparison of current and future period simulations suggests decreases in the frequency of cold extreme events (i.e., cold nights, cold days and cold spells) and in selected return levels of maximum duration of cold spells over the entire study domain. Important regional differences are noticed as the simulations generally indicate smaller decreases in the characteristics of extreme cold events over western Canada compared to the other regions. The analysis also suggests an increase in the frequency of midwinter freeze-thaw events, due mainly to a decrease in the number of frost days and ice days for all Canadian regions. Especially, densely populated southern and coastal Canadian regions will require in depth studies to facilitate appropriate adaptation strategies as these regions are clearly expected to experience large increases in the frequency of freeze-thaw events.

  19. Lagrangian fronts in the ocean

    NASA Astrophysics Data System (ADS)

    Prants, S. V.; Budyansky, M. V.; Uleysky, M. Yu.

    2014-05-01

    We introduce the concept of Lagrangian fronts (LFs) in the ocean and describe their importance for analyzing water mixing and transport and the specific features and differences from hydrological fronts. A method of calculating LFs in a given velocity field is proposed. Based on altimeter velocity fields from AVISO data in the northwestern Pacific, we calculate the Lagrangian synoptic maps and identify LFs of different spatial and temporal scales. Using statistical analysis of saury catches in different years according to the Goskomrybolovstvo (State Fisheries Committee of the Russian Federation), we show that LFs can serve as good indicators of places that are favorable for fishing.

  20. Identification of cold-responsive genes in blueberry (Vaccinium corymbosum L.) using a hybridization approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enhanced cold tolerance, including tolerance to winter freezing and spring frosts, is needed for genetic improvement of current highbush blueberry (Vaccinium corymbosum L.) cultivars. To gain a better understanding of changes in gene expression associated with development of cold tolerance in bluebe...

  1. COLD TEMPERATURE MOTOR VEHICLE EMISSIONS TESTING IN ALASKA

    EPA Science Inventory

    A motor vehicle emissions testing study was conducted in Anchorage and Fairbanks during the winter of 1998-99 to collect actual measurements of initial idle emission rates. The study was performed for a sample of 111 automobiles and light-duty trucks under cold wintertime ambient...

  2. Development of a Model System to Identify Differences in Spring and Winter Oat

    PubMed Central

    Chawade, Aakash; Lindén, Pernilla; Bräutigam, Marcus; Jonsson, Rickard; Jonsson, Anders; Moritz, Thomas; Olsson, Olof

    2012-01-01

    Our long-term goal is to develop a Swedish winter oat (Avena sativa). To identify molecular differences that correlate with winter hardiness, a winter oat model comprising of both non-hardy spring lines and winter hardy lines is needed. To achieve this, we selected 294 oat breeding lines, originating from various Russian, German, and American winter oat breeding programs and tested them in the field in south- and western Sweden. By assaying for winter survival and agricultural properties during four consecutive seasons, we identified 14 breeding lines of different origins that not only survived the winter but also were agronomically better than the rest. Laboratory tests including electrolytic leakage, controlled crown freezing assay, expression analysis of the AsVrn1 gene and monitoring of flowering time suggested that the American lines had the highest freezing tolerance, although the German lines performed better in the field. Finally, six lines constituting the two most freezing tolerant lines, two intermediate lines and two spring cultivars were chosen to build a winter oat model system. Metabolic profiling of non-acclimated and cold acclimated leaf tissue samples isolated from the six selected lines revealed differential expression patterns of 245 metabolites including several sugars, amino acids, organic acids and 181 hitherto unknown metabolites. The expression patterns of 107 metabolites showed significant interactions with either a cultivar or a time-point. Further identification, characterisation and validation of these metabolites will lead to an increased understanding of the cold acclimation process in oats. Furthermore, by using the winter oat model system, differential sequencing of crown mRNA populations would lead to identification of various biomarkers to facilitate winter oat breeding. PMID:22253782

  3. Drivers of Asian winter monsoon evolution since the Last Glacial Maximum (Invited)

    NASA Astrophysics Data System (ADS)

    Morrill, C.; Li, Y.

    2013-12-01

    The Asian winter monsoon is a major center of activity for global winter climate. Its extensive latitudinal reach, in particular, allows it to act as a bridge between extratropical and tropical climate. New loess and ocean sediment records describe how the winter monsoon has evolved over the last 21 ka, with strong phases during the Last Glacial Maximum (LGM) and Early Holocene, and weakening though the Middle and Late Holocene. Abrupt cold events, such as Heinrich event 1 or the 8.2 ka event, were periods of even more intense winter monsoon circulation. Reasons for this evolution have been proposed, but not yet tested using physically-consistent models of the coupled climate system. The causes are likely multiple, since the winter monsoon was strong during both the Early Holocene and the LGM, though the possible drivers (i.e., orbital forcing, greenhouse gas concentration, and ice sheet extent) were quite different between those two time periods. We test these ideas with a series of equilibrium, sensitivity, and transient simulations using the Community Climate System, version 3, coupled climate model. At LGM, the presence of the Laurentide Ice Sheet was primarily responsible for the stronger winter monsoon circulation. Reduced greenhouse gas concentrations at LGM made only a minor contribution. During the Early Holocene, on the other hand, lower winter insolation than today enhanced the land-ocean temperature contrast and strengthened the monsoon circulation. The remnant Laurentide ice sheet of the Early Holocene did not contribute to the stronger winter monsoon. Expansion of Northern Hemisphere sea ice during abrupt cold events increased the latitudinal temperature gradient and intensified winter winds throughout much of the mid-latitudes. Changes in the mechanisms driving winter monsoon behavior through time can also explain the observed covariance with the tropical summer monsoon.

  4. Winter performance of an urban stormwater pond in southern Sweden

    NASA Astrophysics Data System (ADS)

    Semadeni-Davies, Annette

    2006-01-01

    Evidence from cold regions in North America has shown that the performance of stormwater ponds differs between winter and summer. The pond hydraulics change seasonally, and winters have lowered removal efficiency due to a combination of an ice cover, cold water and de-icing salts. This study examines the function of the Bäckaslov stormwater pond under the more mild conditions of southern Sweden, where there are several snow and melt cycles per year.Event sampling in the summer of 1997 showed good removal efficiencies for nutrients, total suspended solids (TSS) and a selection of metals (Cd, Cu, Pb, Zn), but winter grab-tests taken in 1995-96 and 1997-98 suggest that the pond acts as a pollutant source under cold conditions. To better assess winter and spring pond performance, water at the inflow and outflow was sampled from January to April 2003. The low intensity of runoff delivery and slow inflow velocities meant that time- rather than flow-weighted sampling was used. Five consecutive events were sampled and analysed for TSS, chloride and the metals As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. YSI probes were in place at both the inlet (pH, temperature) and outlet (pH, temperature, conductivity, dissolved oxygen) to determine the timing of pollution flows. In addition, profiles of the same quality indicators allowed snapshots of pond processes.De-icing salt has a major effect on pond hydraulics. Strong stratification occurred after each snowmelt-generated flow event and up to 80% of chloride could be retained by the pond. However, continuous conductivity measurements show that chloride is flushed between events. Ice changes retention times and causes oxygen depletion, but bed scour was not observed. Pond performance decreased during the winter and spring, albeit not as badly as the grab tests suggest. A seasonal comparison of the removal efficiencies showed that removal of Cd (75%) and Cu (49%) was about the same for summer and winter-spring, but removal of Pb, Zn and TSS

  5. The Challenge of Winter Backpacking.

    ERIC Educational Resources Information Center

    Cavanaugh, Michael; Mapes, Alan

    1981-01-01

    Tips and techniques for safe and enjoyable winter backpacking are offered. Topics covered include cross county skis, snowshoes, clothing, footwear, shelter, sleeping bags, food, hypothermia prevention, as well as general rules and requirements. (CO)

  6. Red spruce decline---Winter injury and air pollutants

    SciTech Connect

    Roberts, T.M. )

    1989-10-01

    There has been a widespread decline in growth of red spruce (Picea rubens Sarg.) since 1960 in the eastern United States. There is evidence that this decline is at least partly attributable to age- and density-related growth patterns, particularly at lower elevations. Mortality has been severe at high elevation sites where similar episodes have occasionally occurred in the last 100 years. At these sites, periods of low growth preceding 1960 were related to periods with warm late summers and cold early winters. Since 1960, this relationship no longer holds, although there is an association with unusual deviations from mean temperatures. There are field reports that one of the main causes of reduced growth and mortality is apical dieback induced by severe winter conditions. Preliminary observations suggest that high elevation red spruce may not be sufficiently hardened to tolerate low autumn temperatures. However, appearance of injury in the spring, association of injury with wind exposure and correlation of provenance susceptibility with cuticular transpiration rates, including the importance of desiccation injury. Sensitivity to both types of winter injury may be increased by air pollutants (particularly ozone and less probably, acid mist or excess nitrogen deposition). Nutrient deficiency (particularly magnesium and to a lesser extent potassium) may also increase cold sensitivity. The nature and extent of these interactions are being actively researched for red spruce. 48 refs.

  7. Ocean properties, ice-ocean interactions, and calving front morphology at two major west Greenland glaciers

    NASA Astrophysics Data System (ADS)

    Chauché, N.; Hubbard, A.; Gascard, J.-C.; Box, J. E.; Bates, R.; Koppes, M.; Sole, A.; Patton, H.

    2013-11-01

    Warm sub-polar mode water (SPMW) has been identified as a primary driver of mass loss of marine terminating glaciers draining the Greenland Ice Sheet (GrIS) yet, the specific mechanisms by which SPMW interacts with these tidewater termini remain uncertain. We present oceanographic data from Rink Glacier (RG) and Store Glacier (SG) fjords, two major marine outlets draining the western sector of the GrIS into Baffin Bay over the contrasting melt-seasons of 2009 and 2010. Submarine melting occurs wherever ice is in direct contact with warmer water and the consistent presence of 2.8 °C SPMW adjacent to both ice fronts below 400 m throughout all surveys indicates that melting is maintained by a combination of molecular diffusion and large scale, weak convection, diffusional (hereafter called ubiquitous) melting. At shallower depths (50-200 m), cold, brine-enriched water (BEW) formed over winter appears to persist into the summer thereby buffering this melt by thermal insulation. Our surveys reveal four main modes of glacier-ocean interaction, governed by water depth and the rate of glacier runoff water (GRW) injected into the fjord. Deeper than 200 m, submarine melt is the only process observed, regardless of the intensity of GRW or the depth of injection. However, between the surface and 200 m depth, three further distinct modes are observed governed by the GRW discharge. When GRW is weak (≲1000 m3 s-1), upward motion of the water adjacent to the glacier front is subdued, weak forced or free convection plus diffusional submarine melting dominates at depth, and seaward outflow of melt water occurs from the glacier toe to the base of the insulating BEW. During medium intensity GRW (∼1500 m3 s-1), mixing with SPMW yields deep mixed runoff water (DMRW), which rises as a buoyant plume and intensifies local submarine melting (enhanced buoyancy-driven melting). In this case, DMRW typically attains hydrostatic equilibrium and flows seaward at an intermediate depth of

  8. Advanced RF Front End Technology

    NASA Technical Reports Server (NTRS)

    Herman, M. I.; Valas, S.; Katehi, L. P. B.

    2001-01-01

    The ability to achieve low-mass low-cost micro/nanospacecraft for Deep Space exploration requires extensive miniaturization of all subsystems. The front end of the Telecommunication subsystem is an area in which major mass (factor of 10) and volume (factor of 100) reduction can be achieved via the development of new silicon based micromachined technology and devices. Major components that make up the front end include single-pole and double-throw switches, diplexer, and solid state power amplifier. JPL's Center For Space Microsystems - System On A Chip (SOAC) Program has addressed the challenges of front end miniaturization (switches and diplexers). Our objectives were to develop the main components that comprise a communication front end and enable integration in a single module that we refer to as a 'cube'. In this paper we will provide the latest status of our Microelectromechanical System (MEMS) switches and surface micromachined filter development. Based on the significant progress achieved we can begin to provide guidelines of the proper system insertion for these emerging technologies. Additional information is contained in the original extended abstract.

  9. Align the Front End First.

    ERIC Educational Resources Information Center

    Perry, Jim

    1995-01-01

    Discussion of management styles and front-end analysis focuses on a review of Douglas McGregor's theories. Topics include Theories X, Y, and Z; leadership skills; motivational needs of employees; intrinsic and extrinsic rewards; and faulty implementation of instructional systems design processes. (LRW)

  10. Teaching the French Popular Front.

    ERIC Educational Resources Information Center

    Wall, Irwin M.

    1987-01-01

    Examines the French Popular Front of 1936 as a vehicle to investigate the turbulent decade of the 1930s. Reviews current historiography and discusses various facets of Leon Blum's government, examining the interrelationship of major economic and political forces. Concludes that the French Left still faces Blum's dilemma of implementing socialism…

  11. Cold Stress and the Cold Pressor Test

    ERIC Educational Resources Information Center

    Silverthorn, Dee U.; Michael, Joel

    2013-01-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This…

  12. Interview with Wallace D. Winters.

    PubMed

    Winters, Wallace D

    2002-01-01

    Wallace Winters exemplifies the model of the basic scientist/clinical toxicologist. His extensive research interests have led to a better understanding of central nervous system excitation and depression, and have included pioneering studies on the neuropharmacology of gammahydroxy butyrate that date back to the 1960s. Dr. Winters was born in New York, NY on June 20, 1929. He received his undergraduate degree at George Washington University, his Ph.D. in Pharmacology/Toxicology at the University of Wisconsin, and his M.D. at the Medical College of Wisconsin. From 1959 to 1962 Dr. Winters pursued postdoctoral studies at the Brain Research Institute at University of California, Los Angeles where he remained on the faculty rising to full Professor. In 1971, Dr. Winters relocated to University of California at Davis where he served as a Professor of Pharmacology/Toxicology for the next 20 years. During this time, Dr. Winters founded the University of California Davis Poison Control Center in Sacramento in 1977 and served as its first medical director until 1983. From 1979 to 1984 he served on the American Academy of Clinical Toxicology Board of Trustees. After retiring from University of California, Davis, Dr. Winters worked as a Medical Officer for the U.S. Food and Drug Administration from 1991 to 1997, and continues to serve as a consultant and medical expert in clinical pharmacology and toxicology. PMID:12126180

  13. Change in abundance of pacific brant wintering in alaska: evidence of a climate warming effect?

    USGS Publications Warehouse

    Ward, D.H.; Dau, C.P.; Lee, T.; Sedinger, J.S.; Anderson, B.A.; Hines, J.E.

    2009-01-01

    Winter distribution of Pacific Flyway brant (Branta bernicla nigricans) has shifted northward from lowtemperate areas to sub-Arctic areas over the last 42 years. We assessed the winter abundance and distribution of brant in Alaska to evaluate whether climate warming may be contributing to positive trends in the most northern of the wintering populations. Mean surface air temperatures during winter at the end of the Alaska Peninsula increased about 1??C between 1963 and 2004, resulting in a 23% reduction in freezing degree days and a 34% decline in the number of days when ice cover prevents birds from accessing food resources. Trends in the wintering population fluctuated with states of the Pacific Decadal Oscillation, increasing during positive (warm) phases and decreasing during negative (cold) phases, and this correlation provides support for the hypothesis that growth in the wintering population of brant in Alaska is linked to climate warming. The size of the wintering population was negatively correlated with the number of days of strong northwesterly winds in November, which suggests that the occurrence of tailwinds favorable for migration before the onset of winter was a key factor in whether brant migrated from Alaska or remained there during winter. Winter distribution of brant on the Alaska Peninsula was highly variable and influenced by ice cover, particularly at the heavily used Izembek Lagoon. Observations of previously marked brant indicated that the Alaska wintering population was composed primarily of birds originating from Arctic breeding colonies that appear to be growing. Numbers of brant in Alaska during winter will likely increase as temperatures rise and ice cover decreases at high latitudes in response to climate warming. ?? The Arctic Institute of North America.

  14. Fluctuation-controlled front propagation

    NASA Astrophysics Data System (ADS)

    Ridgway, Douglas Thacher

    1997-09-01

    A number of fundamental pattern-forming systems are controlled by fluctuations at the front. These problems involve the interaction of an infinite dimensional probability distribution with a strongly nonlinear, spatially extended pattern-forming system. We have examined fluctuation-controlled growth in the context of the specific problems of diffusion-limited growth and biological evolution. Mean field theory of diffusion-limited growth exhibits a finite time singularity. Near the leading edge of a diffusion-limited front, this leads to acceleration and blowup. This may be resolved, in an ad hoc manner, by introducing a cutoff below which growth is weakened or eliminated (8). This model, referred to as the BLT model, captures a number of qualitative features of global pattern formation in diffusion-limited aggregation: contours of the mean field match contours of averaged particle density in simulation, and the modified mean field theory can form dendritic features not possible in the naive mean field theory. The morphology transition between dendritic and non-dendritic global patterns requires that BLT fronts have a Mullins-Sekerka instability of the wavefront shape, in order to form concave patterns. We compute the stability of BLT fronts numerically, and compare the results to fronts without a cutoff. A significant morphological instability of the BLT fronts exists, with a dominant wavenumber on the scale of the front width. For standard mean field fronts, no instability is found. The naive and ad hoc mean field theories are continuum-deterministic models intended to capture the behavior of a discrete stochastic system. A transformation which maps discrete systems into a continuum model with a singular multiplicative noise is known, however numerical simulations of the continuum stochastic system often give mean field behavior instead of the critical behavior of the discrete system. We have found a new interpretation of the singular noise, based on maintaining

  15. Summer Hot Snaps and Winter Conditions: Modelling White Syndrome Outbreaks on Great Barrier Reef Corals

    PubMed Central

    Heron, Scott F.; Willis, Bette L.; Skirving, William J.; Eakin, C. Mark; Page, Cathie A.; Miller, Ian R.

    2010-01-01

    Coral reefs are under increasing pressure in a changing climate, one such threat being more frequent and destructive outbreaks of coral diseases. Thermal stress from rising temperatures has been implicated as a causal factor in disease outbreaks observed on the Great Barrier Reef, Australia, and elsewhere in the world. Here, we examine seasonal effects of satellite-derived temperature on the abundance of coral diseases known as white syndromes on the Great Barrier Reef, considering both warm stress during summer and deviations from mean temperatures during the preceding winter. We found a high correlation (r2 = 0.953) between summer warm thermal anomalies (Hot Snap) and disease abundance during outbreak events. Inclusion of thermal conditions during the preceding winter revealed that a significant reduction in disease outbreaks occurred following especially cold winters (Cold Snap), potentially related to a reduction in pathogen loading. Furthermore, mild winters (i.e., neither excessively cool nor warm) frequently preceded disease outbreaks. In contrast, disease outbreaks did not typically occur following warm winters, potentially because of increased disease resistance of the coral host. Understanding the balance between the effects of warm and cold winters on disease outbreak will be important in a warming climate. Combining the influence of winter and summer thermal effects resulted in an algorithm that yields both a Seasonal Outlook of disease risk at the conclusion of winter and near real-time monitoring of Outbreak Risk during summer. This satellite-derived system can provide coral reef managers with an assessment of risk three-to-six months in advance of the summer season that can then be refined using near-real-time summer observations. This system can enhance the capacity of managers to prepare for and respond to possible disease outbreaks and focus research efforts to increase understanding of environmental impacts on coral disease in this era of

  16. Changes in hematological profiles during winter field operations

    SciTech Connect

    Lopez, A.; Reed, L.; D'Alesandro, M. )

    1991-03-11

    The authors have previously shown that there are changes in hematological profiles during experimental cold acclimation. They now report on hematological changes in 9 military volunteers during a 12 week winter field operation and show results similar to those observed during experimental cold acclimation. Blood was collected before and after completion of winter field operations and analyzed in a paired fashion. Hematocrit (HCT) and erythrocyte counts (RBC) were decreased; mean corpuscular hemoglobin concentration (MCHC) and plasma volume (PV), which was calculated from hemoglobin (Hb) concentration and HCT, were increased. In addition, the reticulocyte count was increased from 1.37 {plus minus} 0.10% to 2.62 {plus minus} 0.24% after completion of field operations. There was a statistically significant inverse correlation between HCT and reticulocyte count, indicating the need for an enhanced rate of red cell production. Hemoglobin concentration, leukocyte count, and mean corpuscular volume were unchanged. The RBC population, to remain at steady state during periods of chronic cold exposure, shows alterations in the number of circulating cells, Hb concentration per cell and possibly cell turnover.

  17. Crystallization and saturation front propagation in silicic magma chambers

    NASA Astrophysics Data System (ADS)

    Lake, Ethan T.

    2013-12-01

    The cooling and crystallization style of silicic magma bodies in the upper crust falls on a continuum between whole-chamber processes of convection, crystal settling, and cumulate formation and interface-driven processes of conduction and crystallization front migration. In the end-member case of vigorous convection and crystal settling, volatile saturation advances downward from the roof and upward from the floor throughout the chamber. In the end-member case of stagnant magma bodies, volatile saturation occurs along an inward propagating front from all sides of the chamber. Ambient thermal gradient primarily controls the propagation rate; warm (⩾40 °C/km) geothermal gradients lead to thick (1200+ m) crystal mush zones and slow crystallization front propagation. Cold (<40 °C/km) geothermal gradients lead to rapid crystallization front propagation and thin (<1000 m) mush zones. Magma chamber geometry also exerts a first-order control on propagation rates; bodies with high surface to magma volume ratio and large Earth-surface-parallel faces exhibit more rapid propagation and thinner mush zones. Crystallization front propagation occurs at speeds of greater than 10 cm/yr (rhyolitic magma; 1 km thick sill geometry in a 20 °C/km geotherm), far faster than diffusion of volatiles in magma and faster than bubbles can nucleate, grow, and ascend through the chamber. Numerical simulations indicate saturation front propagation is determined primarily by pressure and magma crystallization rate; above certain initial water contents (4.4 wt.% in a dacite) the mobile magma is volatile-rich enough above 10 km depth to always contains a saturation front. Saturation fronts propagate down from the magma chamber roof at lower water contents (3.3 wt.% in a dacite at 5 km depth), creating an upper saturated interface for most common (4-6 wt.%) magma water contents. This upper interface promotes the production of a fluid pocket underneath the apex of the magma chamber. If the fluid

  18. Cold and Cough Medicines

    MedlinePlus

    ... What can you do for your cold or cough symptoms? Besides drinking lots of fluids and getting ... medicines. There are lots of different cold and cough medicines, and they do different things. Nasal decongestants - ...

  19. Cold knife cone biopsy

    MedlinePlus

    A cold knife cone biopsy (conization) is surgery to remove a sample of abnormal tissue from the cervix. The ... Cold knife cone biopsy is done to detect cervical cancer or early changes that lead to cancer. ...

  20. Cold wave lotion poisoning

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002693.htm Cold wave lotion poisoning To use the sharing features on this page, please enable JavaScript. Cold wave lotion is a hair care product used ...

  1. Cold knife cone biopsy

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003910.htm Cold knife cone biopsy To use the sharing features on this page, please enable JavaScript. A cold knife cone biopsy (conization) is surgery to remove ...

  2. Cold Sores (Orofacial Herpes)

    MedlinePlus

    ... rash and rashes clinical tools newsletter | contact Share | Cold Sores (Orofacial Herpes) Information for adults A A ... face, known as orofacial herpes simplex, herpes labialis, cold sores, or fever blisters, is a common, recurrent ...

  3. Cold and Cough Medicines

    MedlinePlus

    ... What can you do for your cold or cough symptoms? Besides drinking plenty of fluids and getting ... medicines. There are lots of different cold and cough medicines, and they do different things. Nasal decongestants - ...

  4. HVAC design considerations for cold climates

    SciTech Connect

    Armstrong, R.S. )

    1993-09-01

    The design of heating, ventilating and air-conditioning (HVAC) systems in cold climate areas requires modifications to the standard designs used in more temperate climates. While most of the US experiences freezing temperatures at least once during the winter months, certain areas experience several months of extended cold. No single location in the US experiences these extended cold conditions more than Alaska. While most areas in the continental US will not require modifications to standard design guidelines, many design modifications commonly used in the Arctic regions of Alaska and Canada can also be applied to any cold climate area in the continental US. The geographic area of Alaska is about one-third the size of the continental US. Climatic extremes range from Ketchikan with 6.697 heating degree days (at 55[degree]21 minutes N latitude) to Barrow with 20,341 heating degree days (at 71[degree]18 minutes N latitude), according to the Arctic Environmental Information and Data Center. The suggestions in this article are a compilation of general approaches the authors used to address the challenge of cold climate design. Of course, each detail design must be adapted to the specific climate and application at hand.

  5. Simultaneous Genetic Analysis of Winterhardiness Traits and Development of Winter Malting Barley Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The practical goal of this project is to develop winter malting barley varieties with superior cold tolerance. The basic goal is to advance our understanding of the genetics of low temperature tolerance and vernalization sensitivity. By addressing the question, “Is vernalization sensitivity required...

  6. A NEW MODEL TO ESTIMATE DAILY ENERGY EXPENDITURE FOR WINTERING WATERFOWL

    EPA Science Inventory

    Activity budgets of wintering waterfowl have been widely used to assess habitat quality. However, when factors such as prey abundance or protection from exposure to cold or wind determine quality, measures of daily energy expenditure (DEE) may be more appropriate for this purpos...

  7. Winter Hydrological and Erosion Processes in the U. S. Palouse Region: Field Experimentation and WEPP Simulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion by water is detrimental to soil fertility and crop yield as well as the environment. For cold areas, knowledge of winter hydrological processes is critical to determining alternative land-use and management practices for reducing soil loss and protecting land and water resources. Adequa...

  8. Covariability of zooplankton gradients with glider-detected density fronts in the Southern California Current System

    NASA Astrophysics Data System (ADS)

    Powell, Jesse R.; Ohman, Mark D.

    2015-02-01

    Fronts represent sharp boundaries between water masses, but seasonal and interannual variation in their occurrence and effects on the distributions of pelagic organisms are poorly understood. This study reports results from six years of ocean front observations (2006-2011) along two transect lines across the Southern California Current System (SCCS) using autonomous Spray ocean gliders. During this time, 154 positive near-surface density fronts were identified within 124 completed transects consisting of nearly 23,000 vertical profiles. The incidence of surface density fronts showed distinct seasonality along line 80 off Pt. Conception, with fewer fronts occurring during winter months and more numerous fronts in the nearshore and during spring, summer and fall. On line 90, fronts were the least common nearshore and most frequent in a transitional region offshore. Horizontal density gradients in the surface layer (0-50 m) were significantly correlated with horizontal gradients in surface layer Chlorophyll-a (Chl-a) fluorescence, as well as with mean volume backscatter (MVBS) recorded by a 750 kHz acoustic Doppler profiler. Density fronts were not only zones of rapidly changing phytoplankton and zooplankton biomass concentrations, but also more likely to be zones of enhanced acoustic backscatter and Chl-a fluorescence than regions flanking the fronts. MVBS and Chl-a gradients were significantly correlated with gradients in other hydrographic variables such as temperature, salinity, and spiciness, and weakly with cross-track current velocity, though density gradients remained the single best predictor of strong MVBS and fluorescence gradients. Large mobile predators foraging in the vicinity of such features could locate habitat with higher zooplankton biomass concentrations up to 85% of the time by traveling up local density gradients (i.e., toward rather than away from denser surface waters). We discuss implications of these results in the context of long-term trends

  9. Reaction front formation in contaminant plumes

    NASA Astrophysics Data System (ADS)

    Cribbin, Laura B.; Winstanley, Henry F.; Mitchell, Sarah L.; Fowler, Andrew C.; Sander, Graham C.

    2014-12-01

    The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front.

  10. Heading for Next Winter Haven

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Approaching its 47th month of a Mars surface mission originally planned to last three months, NASA's Spirit rover was also approaching the northern edge of a low plateau called 'Home Plate.' The rover's operators selected an area with north-facing slope there as a destination where Spirit would have its best chance of surviving low-solar-energy conditions of oncoming Martian winter.

    The yellow line on this map of the Home Plate area indicates Spirit's route from early February 2006, entering the mapped area from the north (top), to late November 2007, on the western edge of the bright-toned Home Plate plateau. The map covers an area about 160 meters (525 feet) across from west to east. Labels indicate the area intended for Spirit to spend many months spanning the rover's third Martian winter, the site where it spent about seven months (April to November 2006) spanning its second winter, and the site where it lost use of the drive motor for one of its six wheels.

    A north-facing slope helps Spirit maximizes electric output from its solar panels during winter months because Spirit is in the southern hemisphere of Mars, so the sun appears only in the northern sky during winter. For the third winter, which will reach its minimum solar-energy days in early June 2008, Spirit faces the challenge of having more dust on its solar panels than it had during its second winter.

    The base image for this map is a portion of a color image taken on Jan. 9, 2007, by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter.

  11. Winter wren populations show adaptation to local climate

    PubMed Central

    Morrison, Catriona A.; Robinson, Robert A.; Pearce-Higgins, James W.

    2016-01-01

    Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λ = 1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain. PMID:27429782

  12. Winter wren populations show adaptation to local climate.

    PubMed

    Morrison, Catriona A; Robinson, Robert A; Pearce-Higgins, James W

    2016-06-01

    Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λ = 1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain. PMID:27429782

  13. Effects of winter feeding on growth, body composition, and processing traits of co-cultured blue catfish, channel catfish, and channel catfish x blue catfish hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many catfish farmers do not feed or feed fish very infrequently during the winter months because feeding activity is reduced at cold water temperatures. However, studies have demonstrated that winter feeding can improve catfish weight gain and processing yield relative to not feeding. We compared ...

  14. Fossils tell of mild winters in an ancient hothouse

    SciTech Connect

    Kerr, R.A.

    1993-08-06

    Fossil evidence from the Eocene points to a warmer winter climate in the continental interior (e.g. North Dakota) than that predicted by computer models. Paleobotanists have been able to quantify approximate winter mean temperatures by using leaf characteristics. As one example, leaves from colder climates have toothed edges. Leaf structure was correlated with modern climate regimes, and these relations were then applied to Eocene fossils. They found cold-month mean temperatures of 1-8[degrees]C in Wyoming and Montana, well above model predictions. Climate models can be manipulated to reproduce these temperatures, but not without overheating the entire globe. The problem could be that the Eocene atmospheric circulation was different from today, something not accounted for well by climate models.

  15. Sex-specific winter distribution in a sexually dimorphic shorebird is explained by resource partitioning

    PubMed Central

    Duijns, Sjoerd; van Gils, Jan A; Spaans, Bernard; ten Horn, Job; Brugge, Maarten; Piersma, Theunis

    2014-01-01

    Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, the bar-tailed godwit Limosa lapponica, in which females have a larger body and a longer bill than males. With respect to the trade-offs that these migratory shorebirds experience in their choice of wintering area, northern and colder wintering sites have the benefit of being closer to the Arctic breeding grounds. According to Bergmann's rule, the larger females should incur lower energetic costs per unit of body mass over males, helping them to winter in the cold. However, as the sexes have rather different bill lengths, differences in sex-specific wintering sites could also be due to the vertical distribution of their buried prey, that is, resource partitioning. Here, in a comparison between six main intertidal wintering areas across the entire winter range of the lapponica subspecies in northwest Europe, we show that the percentage of females between sites was not correlated with the cost of wintering, but was positively correlated with the biomass in the bottom layer and negatively with the biomass in the top layer. We conclude that resource partitioning, rather than relative expenditure advantages, best explains the differential spatial distribution of male and female bar-tailed godwits across northwest Europe. PMID:25505527

  16. Winter lipid depletion of juvenile walleye pollock Theragra chalcogramma in the Doto area, northern Japan.

    PubMed

    Kooka, K; Yamamura, O; Ohkubo, N; Honda, S

    2009-07-01

    Seasonal variation in body size and nutritional condition of juvenile walleye pollock Theragra chalcogramma was examined to elucidate the mechanism underlying their first-winter survival on the continental shelf of the Doto area, northern Japan, based on monthly samples collected over 2 years. Stored lipid mass was highest during autumn, but 93% (2004) and 80% (2005) of lipids were exhausted by the onset of winter. Lipid levels in the winter of 2004 remained low (7-14% of the autumnal maximum), and there was reduced growth rate until the spring, whereas in 2005 lipid levels were higher and more variable (10-46% of the maximum) and some growth occurred. An analysis of the allometric relationships between body size and stored energy showed that larger individuals accumulated disproportionately more energy in the autumn, but the advantage disappeared prior to the winter. In January 2004, stored lipid energy was low throughout the Doto continental shelf relative to the continental slope area. These results suggest that winter feeding opportunities on the shelf are severely limited but not completely absent. Previous studies have shown that winter temperatures on the shelf are lower than those in the slope area. It is possible that juvenile T. chalcogramma survive winter on the shelf without a high level of pre-winter lipid storage because the occasional feeding in the cold shelf water benefits energy conservation. PMID:20738491

  17. An optimal index for measuring the effect of East Asian winter monsoon on China winter temperature

    NASA Astrophysics Data System (ADS)

    Hu, Chundi; Yang, Song; Wu, Qigang

    2015-11-01

    Extreme cold events occur frequently in China. The authors define a representative yet simple index to reveal the monthly changes in China winter temperature associated with the East Asian winter monsoon (EAWM), which is represented by both the leading empirical orthogonal function (EOF) mode and the country-mean temperature index of Chinese 160 gauge stations. A combined technique of correlation and multivariate EOF (Corr-MVEOF) analyses is applied to capture the dominant coupled patterns of EAWM circulation system. Based on the atmospheric circulation features captured by the leading Corr-MVEOF mode, a new EAWM index referred to as CNWMI is derived by using a stepwise regression analysis. The CNWMI highlights the importance of (1) the Mongolia-Siberian High (MSH) and its southward expansion and (2) the Asia-wide meridional dipole anomaly of 500 hPa geopotential height. Compared with the 27 existing EAWM indices, the CNWMI not only best represents the leading modes of both EAWM circulation system and China winter temperature, but also reasonably tracks the intraseasonal-to-interdecadal variations of EAWM so that the monthly intensity of EAWM can be monitored conveniently. In particular, the Aleutian low (AL) is not strongly related to the MSH and may not be responsible for the variability of EAWM/MSH. Moreover, the indices that are highly correlated with the temperature over southern East Asia do not show significant relationships with the AL, which is different from the conventional concept that a strong EAWM/MSH is linked to a deepened AL. In contrast, the anomalous Australia-Maritime Continent low is in good agreement with the variation of EAWM/MSH.

  18. Cough and Cold Medicine Abuse

    MedlinePlus

    ... and Cold Medicine Abuse DrugFacts: Cough and Cold Medicine Abuse Email Facebook Twitter Revised May 2014 Some ... diverted for abuse. How Are Cough and Cold Medicines Abused? Cough and cold medicines are usually consumed ...

  19. Firing up the front line.

    PubMed

    Katzenbach, J R; Santamaria, J A

    1999-01-01

    For many organizations, achieving competitive advantage means eliciting superior performance from employees on the front line--the burger flippers, hotel room cleaners, and baggage handlers whose work has an enormous effect on customers. That's no easy task. Front line workers are paid low wages, have scant hope of advancement, and--not surprisingly--often care little about the company's performance. But then how do some companies succeed in engaging the emotional energy of rank-and-file workers? A team of researchers at McKinsey & Company and the Conference Board recently explored that question and discovered that one highly effective route is demonstrated by the U.S. Marine Corps. The Marines' approach to motivation follows the "mission, values, and pride" path, which researchers say is practical and relevant for the business world. More specifically, the authors say the Marines follow five practices: they over-invest in cultivating core value; prepare every person to lead, including front line supervisors; learn when to create teams and when to create single-leader work groups; attend to all employees, not just the top half; and encourage self-discipline as a way of building pride. The authors admit there are critical differences between the Marines and most businesses. But using vivid examples from companies such as KFC and Marriott International, the authors illustrate how the Marines' approach can be translated for corporate use. Sometimes, the authors maintain, minor changes in a company's standard operating procedure can have a powerful effect on front line pride and can result in substantial payoffs in company performance. PMID:10387573

  20. Deuterium content of snow as an index to winter climate in the Sierra Nevada area

    USGS Publications Warehouse

    Friedman, I.; Smith, G.I.

    1972-01-01

    The winter of 1968-69 produced two to three times the amount of precipitation in the Sierra Nevada area, California and Nevada, as the winter of 1969-70. The deuterium content in snow cores collected at the end of each winter at the same sites, which represents the total snowfall of each interval, shows a depletion in 1968-69 of approximately 20 per mil. The higher snowfall in 1968-69 and the depletion of deuterium can be explained by an uncommonly strong westward flow of cold air over and down the western slopes of the Sierras, which interacted with an eastward flow of moist Pacific air that overrode and mixed with the cold air; this resulted in precipitation that occurred in greater than normal amounts and at a lower than normal temperature. Pluvial periods of the Pleistocene may have had the same shift in air-mass trajectory as the wet 1968-69 year. Snow cores collected in the normal 1970-71 winter have deuterium concentrations that resemble those of the normal 1969-70 winter. Small and nonsystematic differences in samples from these two normal winters are due to variations in climatic character as well as to factors inherent in the sampling sites.

  1. Reproductive arrest and stress resistance in winter-acclimated Drosophila suzukii.

    PubMed

    Toxopeus, Jantina; Jakobs, Ruth; Ferguson, Laura V; Gariepy, Tara D; Sinclair, Brent J

    2016-06-01

    Overwintering insects must survive the multiple-stress environment of winter, which includes low temperatures, reduced food and water availability, and cold-active pathogens. Many insects overwinter in diapause, a developmental arrest associated with high stress tolerance. Drosophila suzukii (Diptera: Drosophilidae), spotted wing drosophila, is an invasive agricultural pest worldwide. Its ability to overwinter and therefore establish in temperate regions could have severe implications for fruit crop industries. We demonstrate here that laboratory populations of Canadian D. suzukii larvae reared under short-day, low temperature, conditions develop into dark 'winter morph' adults similar to those reported globally from field captures, and observed by us in southern Ontario, Canada. These winter-acclimated adults have delayed reproductive maturity, enhanced cold tolerance, and can remain active at low temperatures, although they do not have the increased desiccation tolerance or survival of fungal pathogen challenges that might be expected from a more heavily melanised cuticle. Winter-acclimated female D. suzukii have underdeveloped ovaries and altered transcript levels of several genes associated with reproduction and stress. While superficially indicative of reproductive diapause, the delayed reproductive maturity of winter-acclimated D. suzukii appears to be temperature-dependent, not regulated by photoperiod, and is thus unlikely to be 'true' diapause. The traits of this 'winter morph', however, likely facilitate overwintering in southern Canada, and have probably contributed to the global success of this fly as an invasive species. PMID:27039032

  2. Subjective musculoskeletal symptoms in winter and summer among indoor working construction electricians.

    PubMed

    Inaba, Ryoichi; Mirbod, Seyed Mohammad

    2010-01-01

    To evaluate the effects of cold exposure on the musculoskeletal system, two surveys on the subjective musculoskeletal symptoms among male electricians working in the buildings under construction were performed in winter (N=74) and summer seasons (N=83). A self-administered questionnaire was used to collect information on age, occupational career, working habit, present illness, and subjective musculoskeletal symptoms. Mean age, occupational career and daily smoking of the supervisors were significantly higher than those of the other subjects. In general, prevalence rates of stiffness, numbness, pain and Raynaud's phenomenon in the fingers, finger cold sensation, dull movement of the fingers, pain in the wrist, knee joint pain, pain and numbness in the foot and foot cold sensation in winter were significantly higher than those in summer. These results were marked especially in the workers except supervisors. In winter, there were no significant differences in the prevalence rates of subjective musculoskeletal complaints between the supervisors and the other workers. On the other hand, in summer, prevalence of stiffness and pain in the shoulder, stiffness and pain in the neck, dullness and pain in the arm, finger cold sensation, low back dullness and low back pain in the supervisors were significantly higher than those in the other workers. These results suggest that effects of cold on the musculoskeletal symptoms markedly appeared in the workers except supervisors. PMID:20160405

  3. A Pan-arctic Survey about the Meaning of Winter Respiration in Northern High Latitudes

    NASA Astrophysics Data System (ADS)

    Selbmann, A. K.; Natali, S.

    2015-12-01

    The arctic is warming at twice the rate of the rest of the planet, with the greatest warming occurring during the winter months. Despite the cold temperatures during the winter, microbial activity continues and leads to a release of soil carbon during a criticial period when plant uptake has ceased. Due to the warming climate, huge pools of carbon stored in permafrost soils are expected to be released to the atmosphere. To identify the annual carbon balance of arctic ecosystems and potential impacts caused by a rise in temperatures, understanding the magnitude of winter respiration is essential. In order to refine current and future estimates of carbon loss from permafrost ecosystems, we conducted a pan-arctic synthesis of winter respiration from northern high latitude regions. We examined differences in cumulative winter respiration among permafrost zones, biomes, ecosystem types, and effects of measurement method on winter respiration estimates. We also examined effect of air temperature and precipitation (Worldclim database) on rates of winter respiration. The database contained 169 measurement points from 46 study sites located throughout the permafrost zones. We found that 21.6 % of annual respiration is happening during non-growing season, which can shift ecosystems from annual sinks during the growing season to net sources of carbon on an annual basis. Across studies, the average carbon loss during the winter was 66 g CO2-C. There was a strong relationship between mean annual air temperature and winter respiration, and lower respiration in continuous compared to discontinuous permafrost zones and northern areas without permafrost. The present results clarify the contribution of winter respiration to annual carbon balance and show the sensitivity of carbon release to rising temperatures in northern high latitudes. These results suggest that permafrost degradation and increased temperature will lead to a higher release of carbon from the Arctic in wintertime

  4. The History of Winter: teachers as scientists

    NASA Astrophysics Data System (ADS)

    Koenig, L.; Courville, Z.; Wasilewski, P. J.; Gow, T.; Bender, K. J.

    2013-12-01

    The History of Winter (HOW) is a NASA Goddard Space Flight Center-funded teacher enrichment program that was started by Dr. Peter Wasilewski (NASA), Dr. Robert Gabrys (NASA) and Dr. Tony Gow (Cold Regions Research and Engineering Laboratory, or CRREL) in 2001 and continues with support and involvement of scientists from both the NASA Cryospheric Sciences Laboratory and CREEL. The program brings educators mostly from middle and high schools but also from state parks, community colleges and other institutions from across the US to the Northwood School (a small, private boarding school) in Lake Placid, NY for one week to learn about several facets of winter, polar, and snow research, including the science and history of polar ice core research, lake ice formation and structure, snow pack science, winter ecology, and remote sensing including current and future NASA cryospheric missions. The program receives support from the Northwood School staff to facilitate the program. The goal of the program is to create 'teachers as scientists' which is achieved through several hands-on field experiences in which the teachers have the opportunity to work with polar researchers from NASA, CRREL and partner Universities to dig and sample snow pits, make ice thin sections from lake ice, make snow shelters, and observe under-ice lake ecology. The hands-on work allows the teachers to use the same tools and techniques used in polar research while simultaneously introducing science concepts and activities to support their classroom work. The ultimate goal of the program is to provide the classroom teachers with the opportunity to learn about current and timely cryospheric research as well as to engage in real fieldwork experiences. The enthusiasm generated during the week-long program is translated into classroom activities with guidance from scientists, teachers and educational professionals. The opportunity to engage with polar researchers, both young investigators and renowned

  5. Why Being Cold Might Foster a Cold

    MedlinePlus

    ... These cells produce essential immune system proteins called interferons that respond to a cold virus. The cells ... several degrees below core body temperature, virus-fighting interferons were less able to do their job. The ...

  6. Nuclear winter attracts additional scrutiny

    SciTech Connect

    Smith, R.J.

    1984-07-06

    Prodded by the Natural Resources Defense Council, Congress has asked the Pentagon to provide what amounts to an environmental impact statement on the potential for nuclear weapons explosions to create enough soot and dust to cause a nuclear winter. The request has implications for arms control and civil defense as well as for weapons procurement and deployment. Little attention was given to the atmospheric and climatic effects of nuclear war until the nuclear winter concept was introduced in October of 1983. Only the Navy and the DOE took steps to follow up until pressure was put on Congress and the Pentagon for further study. Pentagon criticism of the nuclear winter presentation argues that the scenario assumptions that cities will be targeted and that a conflict will involve 5000-6500 megatons are incorrect.

  7. Winter Weather Frequently Asked Questions

    MedlinePlus

    ... All What is hypothermia? When exposed to cold temperatures, your body begins to lose heat faster than ... The result is hypothermia, or abnormally low body temperature. Body temperature that is too low affects the ...

  8. Winter storm-induced hydrodynamics and morphological response of a shallow transgressive shoal complex: Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Siadatmousavi, S. Mostafa; Jose, Felix

    2015-03-01

    before and after the deployment in spring 2009 consisted of more than 80% shell and shell hash, which again confirmed a stable bottom as predicted from the PCADP data. However, the fine sand and mud dominated bed at Trinity Shoal was highly dynamic and experienced a few cm of ephemeral sediment deposition during the passage of each cold front, as revealed from the analysis of acoustic backscatter data from the PCADP. Suspended sediment concentration estimated from Optical Backscatterance Sensors (OBS) and PCADP were in good agreement during low river discharge events in December 2008; but significantly diverged during the spring 2009 deployment, when a high suspended sediment load was discharged into the shelf from the Atchafalaya River, and subsequently pushed farther offshore into the deployment sites by wind-induced strong currents during the passage of cold fronts.

  9. How cold is cold dark matter?

    SciTech Connect

    Armendariz-Picon, Cristian; Neelakanta, Jayanth T. E-mail: jtneelak@syr.edu

    2014-03-01

    If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed.

  10. Winter Outdoor Education Activities: Snowshoes and Exploring the Winter Environment.

    ERIC Educational Resources Information Center

    Matthews, Bruce E.; And Others

    Designed as a resource base upon which elementary school educators can build outdoor learning experiences, this resource packet contains a basic, multidisciplinary snowshoeing lesson plan, pre- and post-trip suggestions, and suggestions for further winter outdoor study on snowshoes. Specifically, there are narratives and illustrations addressed at…

  11. Winter Storm Zones on Mars

    NASA Technical Reports Server (NTRS)

    Hollingsworth, J. L.; Haberle, R. M.; Barnes, J. R.; Bridger, A. F. C.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    Preferred regions of weather activity in Mars' winter middle latitudes-so called 'storm zones' are found in a general circulation model of Mars' atmospheric circulation. During northern winter, these storm zones occur in middle latitudes in the major planitia (low-relief regions) of the western and eastern hemisphere. In contrast, the highlands of the eastern hemisphere are mostly quiescent. Compared to Earth's storm zones where diabatic heating associated with land-sea thermal contrasts is crucial, orography on Mars is fundamental to the regionalization of weather activity. Future spacecraft missions aimed at assessing Mars' climate and its variability need to include such regions in observation strategies.

  12. Seasonal thermal fronts on the northern South China Sea shelf: Satellite measurements and three repeated field surveys

    NASA Astrophysics Data System (ADS)

    Jing, Zhiyou; Qi, Yiquan; Fox-Kemper, Baylor; Du, Yan; Lian, Shumin

    2016-03-01

    Seasonal thermal fronts associated with wind-driven coastal downwelling/upwelling in the northern South China Sea are investigated using satellite measurements and three repeated fine-resolution mapping surveys in winter, spring, and summer. The results show that vigorous thermal fronts develop over the broad shelf with variable widths and intensities in different seasons, which tend to be approximately aligned with the 20-100 m isobaths. Driven by the prevailing winter/summer monsoon, the band-shaped fronts were observed with a magnitude exceeding 0.1°C/km in the subsurface, and accompanied by energetic coastal downwelling/upwelling due to shoreward/offshore Ekman transport. The downward/upward tilting of seasonal thermoclines across the shelf exceeds 20 m, significantly contributing to the development of thermal fronts over the shelf. In addition, the diagnostic analysis of Potential Vorticity (PV) suggests that the summer frontal activities induced by the coastal upwelling are more stable to convection and symmetric instabilities in comparison to the winter fronts associated with downwelling-favorable monsoon forcing. This is primarily due to their essential differences in the upper ocean stratification and horizontal buoyancy gradients arising from wind forcing. At the same time, the coastal currents are substantially regulated by the seasonal winds. An expected lag correlation between the velocity from mooring measurements and alongshore wind stress is detected near the frontal region. These results indicate that seasonal wind forcing plays an important role in the frontal activities and coastal water transport over the shelf.

  13. Atmospheric density remote sensing of mesosphere and thermosphere to be used for spacecraft design by adopting VHF radar and HF Doppler sounder at low latitude West Pacific site during winter

    NASA Astrophysics Data System (ADS)

    Hung, R. J.; Lee, C. C.; Chen, A. J.

    The VHF radar and HF Doppler sounder located at the subtropical and low latitude observing site of Taiwan has been used to make a simultaneous observation for atmospheric parameters from the troposphere, to the middle atmosphere, and then to the thermosphere during the time period of the weak convective motions of cold front in winter time. For observations at mesospheric heights, time dependent wind velocities with three-dimensional profiles are detected in the backscattered power, radial velocities and Doppler spectral width. For observations at thermospheric heights, time-dependent phase path change of high frequency radio wave reflected from ionospheric heights is used to measure Doppler frequency variation of gravity wave parameters. The density perturbations caused by the propagation of the gravity waves due to the weak convective motions in winter time were calculated from the VHF radar and HF Doppler sounder observations simultaneously. These short-term middle atmospheric and thermospheric density changes are a key element needed for space vehicle design purposes. Projects such as the Space Shuttle, Shuttle II, Tethered Satellite, Hubble Space Telescope, Aerobraking Orbital Transfer Vehicle, and Aeroassisted Flight Experiment will benefit from such studies.

  14. Human responses to cold.

    PubMed

    Rintamäki, Hannu

    2007-01-01

    The thermoneutral ambient temperature for naked and resting humans is ca. 27 degrees C. Exposure to cold stimulates cold receptors of the skin which causes cold thermal sensations and stimulation of the sympathetic nervous system. Sympathetic stimulation causes vasoconstriction in skin, arms and legs. Diminished skin and extremity blood flow increases the thermal insulation of superficial tissues more than 300% corresponding to 0.9 clo (0.13 degrees C x m(-2) x W(-1)). With thermoregulatory vasoconstriction/ vasodilatation the body heat balance can be maintained within a range of ca. 4 degrees C, the middle of the range being at ca. 21 degrees C when light clothing is used. Below the thermoneutral zone metabolic heat production (shivering) is stimulated and above the zone starts heat loss by evaporation (sweating). Cold induced vasoconstriction increases blood pressure and viscosity and decreases plasma volume consequently increasing cardiac work. Cold induced hypertensive response can be counteracted by light exercise, while starting heavy work in cold markedly increases blood pressure. Under very cold conditions the sympathetic stimulation opens the anastomoses between arterioles and venules which increases skin temperatures markedly but temporarily, especially in finger tips. Adaptation to cold takes ca. 2 weeks, whereafter the physiological responses to cold are attenuated and cold exposure is subjectively considered less stressful. PMID:17929604

  15. Instability of evaporation fronts in the interstellar medium

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2013-12-10

    The neutral component of the interstellar medium is segregated into the cold neutral medium (CNM) and warm neutral medium (WNM) as a result of thermal instability. It was found that a plane-parallel CNM-WNM evaporation interface, across which the CNM undergoes thermal expansion, is linearly unstable to corrugational disturbances, in complete analogy with the Darrieus-Landau instability (DLI) of terrestrial flames. We perform a full linear stability analysis as well as nonlinear hydrodynamic simulations of the DLI of such evaporation fronts in the presence of thermal conduction. We find that the DLI is suppressed at short length scales by conduction. The length and time scales of the fastest growing mode are inversely proportional to the evaporation flow speed of the CNM and its square, respectively. In the nonlinear stage, the DLI saturates to a steady state where the front deforms to a finger-like shape protruding toward the WNM, without generating turbulence. The evaporation rate at nonlinear saturation is larger than the initial plane-parallel value by a factor of ∼2.4 when the equilibrium thermal pressure is 1800 k {sub B} cm{sup –3} K. The degrees of front deformation and evaporation-rate enhancement at nonlinear saturation are determined primarily by the density ratio between the CNM and WNM. We demonstrate that the Field length in the thermally unstable medium should be resolved by at least four grid points to obtain reliable numerical outcomes involving thermal instability.

  16. Distribution patterns during winter and fidelity to wintering areas of American black ducks

    USGS Publications Warehouse

    Diefenbach, D.R.; Nichols, J.D.; Hines, J.E.

    1988-01-01

    The distribution patterns during winter of American black ducks were compared among age-sex classes using band recivery data. In addition, fidelity to wintering areas was compared between sexes and between coastal and inland wintering sites.

  17. Enzymatic activity of rodents acclimated to cold and long scotophase

    NASA Astrophysics Data System (ADS)

    Fourie, F. Le R.; Haim, A.

    1980-09-01

    Rodents representative of a diurnal species ( Rhabdomys pumilio) as well as a nocturnal species ( Praomys natalensis) were acclimated to cold (Ta = 8°C) at a photoperiod of LD 12:12 and a long scotophase (LD 8; 16) at a temperature of 25° C(Ta). Control groups were kept for both species at Ta = 25° C and LD 12:12 and winter acclimated individuals were obtained during July and August to serve as further reference. Blood samples obtained from the tail were analysed for enzymes representative of three major biochemical pathways. The enzymatic activity of LDH (glycolytic pathway), MDH (Krebs cycle) and G6PDH (hexose monophosphate shunt, as an indicator of gonadal activity) were monitored to represent metabolic activity of the respective cycles. Cold acclimated as well as winter acclimatized mice revealed similar enzymatic patterns for both species and significant increases in LDH and MDH were recorded with a concurrent decrease in G6PDH activity. Specimens exposed to long scotophase exhibited similar enzymatic patterns for both species studied, but enzymatic activity was higher than those of cold acclimated individuals. From these results it is concluded that cold as well as long scotophase induce metabolic adaptations through biochemical activity in the experimental animals. The effect of long scotophase is assumed to be an important factor in the induction of winter acclimatization.

  18. Winter Snowfall Turns an Emerald White

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Ireland's climate is normally mild due to the nearby Gulf Stream, but the waning days of 2000 saw the Emerald Isle's green fields swathed in an uncommon blanket of white. The contrast between summer and winter is apparent in this pair of images of southwestern Ireland acquired by MISR's vertical-viewing (nadir) camera on August 23, 2000 (left) and December 29, 2000 (right). The corresponding Terra orbit numbers are 3628 and 5492, respectively.

    The year 2000 brought record-breaking weather to the British Isles. England and Wales experienced the wettest spring and autumn months since 1766. Despite being one of the warmest years in recent history, a cold snap arrived between Christmas and New Year's Day. According to the UK Meteorological Office, the 18 centimeters (7 inches) of snow recorded at Aldergrove, Northern Ireland, on December 27-28 was the deepest daily fall since 1930.

    Prominent geographical features visible in the MISR images include Galway Bay near the top left. Further south, the mouth of the River Shannon, the largest river in the British Isles, meets the Atlantic Ocean. In the lower portions of the images are the counties of Limerick, Kerry and Cork.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology

  19. Winter Frosted Dunes in Kaiser Crater

    NASA Technical Reports Server (NTRS)

    2001-01-01

    As the Mars Global Surveyor Primary Mission draws to an end, the southern hemisphere of Mars is in the depths of winter. At high latitudes, it is dark most, if not all, of the day. Even at middle latitudes, the sun shines only thinly through a veil of water and carbon dioxide ice clouds, and the ground is so cold that carbon dioxide frosts have formed. Kaiser Crater (47oS, 340oW) is one such place. At a latitude comparable to Seattle, Washington, Duluth, Minnesota, or Helena, Montana, Kaiser Crater is studied primarily because of the sand dune field found within the confines of its walls (lower center of the Mars Orbiter Camera image, above). The normally dark-gray or blue-black sand can be seen in this image to be shaded with light-toned frost. Other parts of the crater are also frosted. Kaiser Crater and its dunes were the subject of an earlier presentation of results. Close-up pictures of these and other dunes in the region show details of their snow-cover, including small avalanches. The two Mars Global Surveyor Mars Orbiter Camera images that comprise this color view (M23-01751 and M23-01752) were acquired on January 26, 2001.

  20. Shock-front broadening in polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Barber, J. L.; Kadau, K.

    2008-04-01

    We analyze a model for the evolution of shock fronts in polycrystalline materials. This model is based on the idea of Meyers and Carvalho [Mater. Sci. Eng. 24, 131 (1976)] that the shock velocity anisotropy within the polycrystal is the most important factor in shock front broadening. Our analysis predicts that the shock front width increases as the 1/2 power of the front penetration distance into the crystal. Our theoretical prediction is in plausible agreement with previous experimental results for the elastic precursor rise time, and it should therefore provide a useful shock width estimate. Furthermore, our theoretical framework is also applicable to other problems involving front propagation in heterogeneous media.

  1. The Winter 2010 and 2011 FRONT/NIRSS In-Flight Icing Hazard Detection Project

    NASA Technical Reports Server (NTRS)

    Serke, David; Hubbert, John; Reehorst, Andrew; Kennedy, Patrick; Politovich, Marcia

    2011-01-01

    The NASA Icing Remote Sensing System (NIRSS) deploys a vertically-pointing K-band radar, a lidar ceiliometer, and a profiling microwave radiometer to obtain measurements for diagnosing local inflight icing conditions. RAL is working with NASA GRC to develop algorithms and data ingest and display software for the system. NASA has an ongoing activity to develop remote sensing technologies for the detection and measurement of icing conditions aloft. As part of that effort NASA teamed with NCAR to develop software that fuses data from multiple instruments into a single detected icing condition product. The multiple instrument approach, which is the current emphasis of this activity, utilizes a K-band vertical staring radar, a microwave radiometer that detects twelve frequencies between 22 and 59 GHz, and a lidar ceilometer. The radar data determine cloud boundaries, the radiometer determines the sub-freezing temperature heights and total liquid water content, and the ceilometer refines the lower cloud boundary. Data is post-processed in C++ program with a Java-based web display of resultant supercooled LWC profile and aircraft hazard identification. In 2010, a multi-channel scanning radiometer, designed and built by Radiometrics, Inc. under a SBIR grant,,was added to the system to assess its utility in improving icing diagnoses.

  2. Reducing winter injury in blackberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the combination of primocane training and cane positioning techniques using a rotatable cross-arm (RCA) trellis system and covering plants in winter to protect buds and canes from freezing temperatures in ‘Apache’, ‘Boysenberry’, ‘Siskiyou’, and ‘Triple Crown’ blackberry. After tying p...

  3. Is "Warm Arctic, Cold Continent" A Fingerprint Pattern of Climate Change?

    NASA Astrophysics Data System (ADS)

    Hoerling, M. P.; Sun, L.; Perlwitz, J.

    2015-12-01

    Cold winters and cold waves have recently occurred in Europe, central Asia and the Midwest to eastern United States, even as global mean temperatures set record highs and Arctic amplification of surface warming continued. Since 1979, Central Asia winter temperatures have in fact declined. Conjecture has it that more cold extremes over the mid-latitude continents should occur due to global warming and the impacts of Arctic sea ice loss. A Northern Hemisphere temperature signal termed the "Warm Arctic, Cold Continent" pattern has thus been surmised. Here we use a multi-model approach to test the hypothesis that such a pattern is indeed symptomatic of climate change. Diagnosis of a large model ensemble of historical climate simulations shows some individual realizations to yield cooling trends over Central Asia, but importantly the vast majority show warming. The observed cooling has thus likely been a low probability state of internal variability, not a fingerprint of forced climate change. We show that daily temperature variations over continents decline in winter due to global warming, and cold waves become less likely. This is partly related to diminution of Arctic cold air reservoirs due to warming-induced sea ice loss. Nonetheless, we find some evidence and present a physical basis that Arctic sea ice loss alone can induce a winter cooling over Central Asia, though with a magnitude that is appreciably smaller than the overall radiative-forced warming signal. Our results support the argument that recent cooling trends over central Asia, and cold extreme events over the winter continents, have principally resulted from atmospheric internal variability and have been neither a forced response to Arctic seas ice loss nor a symptom of global warming. The paradigm of climate change is thus better expressed as "Warm Arctic, Warm Continent" for the NH winter.

  4. Coastal upwelling in the East China Sea in winter

    NASA Astrophysics Data System (ADS)

    Qiao, Fangli; Yang, Yongzeng; Lü, Xingang; Xia, Changshui; Chen, Xianyao; Wang, Baodong; Yuan, Yeli

    2006-11-01

    The dynamic mechanisms of the upwelling off the East China Sea (ECS) coast in wintertime are studied. First, the upwelling signals off the ECS coast are identified by the observed temperature, salinity, nutrients, and dissolved oxygen data obtained during the cruises in January 1999. The MASNUM wave-tide-circulation coupled model is then employed to simulate the hydrography of the ECS. Comparisons between the simulations and observations show that the model performance is satisfactory. On the basis of successful simulation, four numerical experiments are conducted to investigate the upwelling mechanisms. The results suggest that the density (or salinity) front, which separates the inshore Low Salinity Coastal Water and the offshore Taiwan Warm Current (TWC), is the primary inducement for the upwelling. Owing to strong density gradient, the baroclinic pressure gradient force (PGF) is quite large near the frontal zone, and this PGF elicits an upwelling branch along the topography slope. Wind, TWC, and tide affect the density front in extension and intensity, thus exerting subsidiary influences on the upwelling. According to Ekman's theory, the northerly monsoon is downwelling favorable. However, the net effects of wind on the upwelling off the ECS coast in winter are positive because it drives the Changjiang River Diluted Water (CDW) flowing southward and forms the density front. Similarly, the resultant effects of TWC on the upwelling are negative for obstructing the pathway of CDW. Tide contributes to the upwelling because tidal mixing facilitates the expansion of CDW.

  5. Nesting habitat of the Tule Greater White-fronted Goose Anser albifrons elgasi

    USGS Publications Warehouse

    Densmore, R.V.; Ely, C.R.; Bollinger, K.S.; Kratzer, S.; Udevitz, M.S.; Fehringer, D.J.; Rothe, T.C.

    2006-01-01

    This paper presents the first information on the availability and use of nesting habitat by the rare Tule Greater White-fronted Goose Anser albifrons elgasi. The breeding range was sampled by marking geese with radio transmitters on wintering and moulting areas, and tracking them to nest sites in Alaska. Nesting habitat was described at the scales of ecoregion, wetland ecosystem (National Wetlands Inventory (NWI) maps), vegetation type within wetland (Alaska Vegetation Classification (AVC) maps based on satellite imagery), and nest site. Tule Greater White-fronted Goose nests were located in boreal forest wetlands in the upper Cook Inlet Basin ecoregion. Nesting Tule Greater White-fronted Geese selected NWT Palustrine Seasonally Flooded wetlands and used NWI Palustrine Saturated wetlands in proportion to availability. Within these wetlands, Tule Greater White-fronted Geese used Needleleaf Forest, Low Shrub and Herbaceous (mostly graminoid) AVC classes for nest sites in proportion to availability Most (93%) Tule Greater White-fronted Geese nested > 75 m from open water ponds or lakes, and many nested in wetlands with little or no open water. Tule Greater White-fronted Geese nest only in a small breeding area near the most human-impacted area of the state, and continued development may limit the use of suitable nesting habitat.

  6. Cold pool dissipation

    NASA Astrophysics Data System (ADS)

    Grant, Leah D.; Heever, Susan C.

    2016-02-01

    The mechanisms by which sensible heat fluxes (SHFs) alter cold pool characteristics and dissipation rates are investigated in this study using idealized two-dimensional numerical simulations and an environment representative of daytime, dry, continental conditions. Simulations are performed with no SHFs, SHFs calculated using a bulk formula, and constant SHFs for model resolutions with horizontal (vertical) grid spacings ranging from 50 m (25 m) to 400 m (200 m). In the highest resolution simulations, turbulent entrainment of environmental air into the cold pool is an important mechanism for dissipation in the absence of SHFs. Including SHFs enhances cold pool dissipation rates, but the processes responsible for the enhanced dissipation differ depending on the SHF formulation. The bulk SHFs increase the near-surface cold pool temperatures, but their effects on the overall cold pool characteristics are small, while the constant SHFs influence the near-surface environmental stability and the turbulent entrainment rates into the cold pool. The changes to the entrainment rates are found to be the most significant of the SHF effects on cold pool dissipation. SHFs may also influence the timing of cold pool-induced convective initiation by altering the environmental stability and the cold pool intensity. As the model resolution is coarsened, cold pool dissipation is found to be less sensitive to SHFs. Furthermore, the coarser resolution simulations not only poorly but sometimes wrongly represent the SHF impacts on the cold pools. Recommendations are made regarding simulating the interaction of cold pools with convection and the land surface in cloud-resolving models.

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

    NASA Technical Reports Server (NTRS)

    Foster, J. L.

    1980-01-01

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

  8. Cold fusion, Alchemist's dream

    SciTech Connect

    Clayton, E.D.

    1989-09-01

    In this report the following topics relating to cold fusion are discussed: muon catalysed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalysed cold fusion; vibrational mechanisms in excited states of D{sub 2} molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D{sub 2} fusion at low energies; fusion of deuterons into {sup 4}He; secondary D+T fusion within the hydrogenated metal lattice; {sup 3}He to {sup 4}He ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of {sup 3}He/{sup 4}He.

  9. Divergence of the diapause transcriptome in apple maggot flies: winter regulation and post-winter transcriptional repression.

    PubMed

    Meyers, Peter J; Powell, Thomas H Q; Walden, Kimberly K O; Schieferecke, Adam J; Feder, Jeffrey L; Hahn, Daniel A; Robertson, Hugh M; Berlocher, Stewart H; Ragland, Gregory J

    2016-09-01

    The duration of dormancy regulates seasonal timing in many organisms and may be modulated by day length and temperature. Though photoperiodic modulation has been well studied, temperature modulation of dormancy has received less attention. Here, we leverage genetic variation in diapause in the apple maggot fly, Rhagoletis pomonella, to test whether gene expression during winter or following spring warming regulates diapause duration. We used RNAseq to compare transcript abundance during and after simulated winter between an apple-infesting population and a hawthorn-infesting population where the apple population ends pupal diapause earlier than the hawthorn-infesting population. Marked differences in transcription between the two populations during winter suggests that the 'early' apple population is developmentally advanced compared with the 'late' hawthorn population prior to spring warming, with transcripts participating in growth and developmental processes relatively up-regulated in apple pupae during the winter cold period. Thus, regulatory differences during winter ultimately drive phenological differences that manifest themselves in the following summer. Expression and polymorphism analysis identify candidate genes in the Wnt and insulin signaling pathways that contribute to population differences in seasonality. Both populations remained in diapause and displayed a pattern of up- and then down-regulation (or vice versa) of growth-related transcripts following warming, consistent with transcriptional repression. The ability to repress growth stimulated by permissive temperatures is likely critical to avoid mismatched phenology and excessive metabolic demand. Compared with diapause studies in other insects, our results suggest some overlap in candidate genes/pathways, though the timing and direction of changes in transcription are likely species specific. PMID:27312473

  10. Deadly Cold: Health Hazards Due to Cold Weather. An Information Paper by the Subcommittee on Health and Long-Term Care of the Select Committee on Aging. House of Representatives, Ninety-Eighth Congress, Second Session (February 1984).

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Select Committee on Aging.

    This paper, on the health hazards of cold weather for elderly persons, presents information from various sources on the death rates in winter throughout the United States. After reviewing the scope of the problem, specific health hazards associated with cold weather are discussed, i.e., hypothermia, fires, carbon monoxide poisoning, and influenza…

  11. Passive thermal refugia provided warm water for Florida manatees during the severe winter of 2009-2010

    USGS Publications Warehouse

    Stith, B.M.; Slone, D.H.; de Wit, M.; Edwards, H.H.; Langtimm, C.A.; Swain, E.D.; Soderqvist, L.E.; Reid, J.P.

    2012-01-01

    Haloclines induced by freshwater inflow over tidal water have been identified as an important mechanism for maintaining warm water in passive thermal refugia (PTR) used by Florida manatees Trichechus manatus latirostris during winter in extreme southwestern Florida. Record-setting cold during winter 2009–2010 resulted in an unprecedented number of manatee deaths, adding to concerns that PTR may provide inadequate thermal protection during severe cold periods. Hydrological data from 2009–2010 indicate that 2 canal systems in the Ten Thousand Islands (TTI) region acted as PTR and maintained warm bottom-water temperatures, even during severe and prolonged cold periods. Aerial survey counts of live and dead manatees in TTI during the winter of 2009–2010 suggest that these PTR were effective at preventing mass mortality from hypothermia, in contrast to the nearby Everglades region, which lacks similar artificial PTR and showed high manatee carcass counts. Hydrological data from winter 2008–2009 confirmed earlier findings that without haloclines these artificial PTR may become ineffective as warm-water sites. Tidal pumping of groundwater appears to provide additional heat to bottom water during low tide cycles, but the associated thermal inversion is not observed unless salinity stratification is present. The finding that halocline-driven PTR can maintain warm water even under extreme winter conditions suggests that they may have significant potential as warm-water sites. However, availability and conflicting uses of freshwater and other management issues may make halocline-driven PTR unreliable or difficult to manage during winter.

  12. Wintering ecology of adult North American ospreys

    USGS Publications Warehouse

    Washburn, Brian E.; Martell, Mark S.; Bierregaard, Richard O., Jr.; Henny, Charles J.; Dorr, Brian S.; Olexa, Thomas J.

    2014-01-01

    North American Ospreys (Pandion haliaetus) typically migrate long distances to their wintering grounds in the tropics. Beyond the general distribution of their wintering range (i.e., the Caribbean, South America, and Central America), very little is known about the wintering ecology of these birds. We used satellite telemetry to determine the duration of wintering period, to examine the characteristics of wintering areas used by Ospreys, and to quantify space use and activity patterns of wintering Ospreys. Adult Ospreys migrated to wintering sites and exhibited high wintering site fidelity among years. Overall, Ospreys wintered on river systems (50.6%) more than on lakes (19.0%), and use of coastal areas was (30.4%) intermediate. Ospreys remained on their wintering grounds for an average of 154 d for males and 167 d for females. Locations of wintering Ospreys obtained via GPS-capable satellite telemetry suggest these birds move infrequently and their movements are very localized (i.e., 2 and 1.4 km2, respectively. Overall, our findings suggest wintering adult North American Ospreys are very sedentary, demonstrating a pattern of limited daily movements and high fidelity to a few select locations (presumably roosts). We suggest this wintering strategy might be effective for reducing the risk of mortality and maximizing energy conservation.

  13. Winter movement dynamics of Black Brant

    USGS Publications Warehouse

    Lindberg, Mark S.; Ward, David H.; Tibbitts, T. Lee; Roser, John

    2007-01-01

    Although North American geese are managed based on their breeding distributions, the dynamics of those breeding populations may be affected by events that occur during the winter. Birth rates of capital breeding geese may be influenced by wintering conditions, mortality may be influenced by timing of migration and wintering distribution, and immigration and emigration among breeding populations may depend on winter movement and timing of pair formation. We examined factors affecting movements of black brant (Branta bernicla nigricans) among their primary wintering sites in Mexico and southern California, USA, (Mar 1998-Mar 2000) using capture-recapture models. Although brant exhibited high probability (>0.85) of monthly and annual fidelity to the wintering sites we sampled, we observed movements among all wintering sites. Movement probabilities both within and among winters were negatively related to distance between sites. We observed a higher probability both of southward movement between winters (Mar to Dec) and northward movement between months within winters. Between-winter movements were probably most strongly affected by spatial and temporal variation in habitat quality as we saw movement patterns consistent with contrasting environmental conditions (e.g., La Niña and El Niño southern oscillation cycles). Month-to-month movements were related to migration patterns and may also have been affected by differences in habitat conditions among sites. Patterns of winter movements indicate that a network of wintering sites may be necessary for effective conservation of brant.

  14. Double-Front Detonation Waves

    NASA Astrophysics Data System (ADS)

    Gubin, S. A.; Sumskoi, S. I.; Victorov, S. B.

    According to the theory of detonation, in a detonation wave there is a sound plane, named Chapman-Jouguet (CJ) plane. There are certain stationary parameters for this plane. In this work the possibility of the second CJ plane is shown. This second CJ plane is stationary as well. The physical mechanism of non-equilibrium transition providing the existence of the second CJ plane is presented. There is a non-equilibrium state, when the heat is removed from the reaction zone and the heat capacity decreases sharply. As a result of this non-equilibrium state, the sound velocity increases, and the local supersonic zone with second sonic plane (second CJ plane) appears. So the new mode of detonation wave is predicted. Equations describing this mode of detonation are presented. The exact analytical solution for the second CJ plane parameters is obtained. The example of double-front detonation in high explosive (TNT) is presented. In this double-front structure "nanodiamond-nanographite" phase transition takes place in condensed particles of detonation products.

  15. Dipolarization Fronts from Reconnection Onset

    NASA Astrophysics Data System (ADS)

    Sitnov, M. I.; Swisdak, M. M.; Merkin, V. G.; Buzulukova, N.; Moore, T. E.

    2012-12-01

    Dipolarization fronts observed in the magnetotail are often viewed as signatures of bursty magnetic reconnection. However, until recently spontaneous reconnection was considered to be fully prohibited in the magnetotail geometry because of the linear stability of the ion tearing mode. Recent theoretical studies showed that spontaneous reconnection could be possible in the magnetotail geometries with the accumulation of magnetic flux at the tailward end of the thin current sheet, a distinctive feature of the magnetotail prior to substorm onset. That result was confirmed by open-boundary full-particle simulations of 2D current sheet equilibria, where two magnetotails were separated by an equilibrium X-line and weak external electric field was imposed to nudge the system toward the instability threshold. To investigate the roles of the equilibrium X-line, driving electric field and other parameters in the reconnection onset process we performed a set of 2D PIC runs with different initial settings. The investigated parameter space includes the critical current sheet thickness, flux tube volume per unit magnetic flux and the north-south component of the magnetic field. Such an investigation is critically important for the implementation of kinetic reconnection onset criteria into global MHD codes. The results are compared with Geotail visualization of the magnetotail during substorms, as well as Cluster and THEMIS observations of dipolarization fronts.

  16. Winter and early spring CO2 efflux from tundra communities of northern Alaska

    NASA Astrophysics Data System (ADS)

    Fahnestock, J. T.; Jones, M. H.; Brooks, P. D.; Walker, D. A.; Welker, J. M.

    1998-11-01

    Carbon dioxide concentrations through snow were measured in different arctic tundra communities on the North Slope of Alaska during winter and early spring of 1996. Subnivean CO2 concentrations were always higher than atmospheric CO2. A steady state diffusion model was used to generate conservative estimates of CO2 flux to the atmosphere. The magnitude of CO2 efflux differed with tundra community type, and rates of carbon release increased from March to May. Winter CO2 efflux was highest in riparian and snow bed communities and lowest in dry heath, upland tussock, and wet sedge communities. Snow generally accrues earlier in winter and is deeper in riparian and snow bed communities compared with other tundra communities, which are typically windswept and do not accumulate much snow during the winter. These results support the hypothesis that early and deep snow accumulation may insulate microbial populations from very cold temperatures, allowing sites with earlier snow cover to sustain higher levels of activity throughout winter compared to communities that have later developing snow cover. Extrapolating our estimates of CO2 efflux to the entire snow-covered season indicates that total carbon flux during winter in the Arctic is 13-109 kg CO2-C ha-1, depending on the vegetation community type. Wintertime CO2 flux is a potentially important, yet largely overlooked, part of the annual carbon cycle of tundra, and carbon release during winter should be accounted for in estimates of annual carbon balance in arctic ecosystems.

  17. Informing the Front Line about Common Respiratory Viral Epidemics

    PubMed Central

    Gesteland, Per H; Samore, Matthew H; Pavia, Andrew T; Srivastava, Rajendu; Korgenski, Kent; Gerber, Kristine; Daly, Judy A; Mundorff, Michael B; Rolfs, Robert T; James, Brent C.; Byington, Carrie L.

    2007-01-01

    The nature of clinical medicine is to focus on individuals rather than the populations from which they originate. This orientation can be problematic in the context of acute healthcare delivery during routine winter outbreaks of viral respiratory disease where an individual’s likelihood of viral infection depends on knowledge of local disease incidence. The level of interest in and perceived utility of community and regional infection data for front line clinicians providing acute care is unclear. Based on input from clinicians, we developed an automated analysis and reporting system that delivers pathogen-specific epidemic curves derived from a viral panel that tests for influenza, RSV, adenovirus, parainfluenza and human metapneumovirus. Surveillance summaries were actively e-mailed to clinicians practicing in emergency, urgent and primary care settings and posted on a web site for passive consumption. We demonstrated the feasibility and sustainability of a system that provides both timely and clinically useful surveillance information. PMID:18693841

  18. Nonlinear effects of climate on boreal rodent dynamics: mild winters do not negate high-amplitude cycles.

    PubMed

    Korpela, Katri; Delgado, Maria; Henttonen, Heikki; Korpimäki, Erkki; Koskela, Esa; Ovaskainen, Otso; Pietiäinen, Hannu; Sundell, Janne; Yoccoz, Nigel G; Huitu, Otso

    2013-03-01

    Small rodents are key species in many ecosystems. In boreal and subarctic environments, their importance is heightened by pronounced multiannual population cycles. Alarmingly, the previously regular rodent cycles appear to be collapsing simultaneously in many areas. Climate change, particularly decreasing snow quality or quantity in winter, is hypothesized as a causal factor, but the evidence is contradictory. Reliable analysis of population dynamics and the influence of climate thereon necessitate spatially and temporally extensive data. We combined data on vole abundances and climate, collected at 33 locations throughout Finland from 1970 to 2011, to test the hypothesis that warming winters are causing a disappearance of multiannual vole cycles. We predicted that vole population dynamics exhibit geographic and temporal variation associated with variation in climate; reduced cyclicity should be observed when and where winter weather has become milder. We found that the temporal patterns in cyclicity varied between climatically different regions: a transient reduction in cycle amplitude in the coldest region, low-amplitude cycles or irregular dynamics in the climatically intermediate regions, and strengthening cyclicity in the warmest region. Our results did not support the hypothesis that mild winters are uniformly leading to irregular dynamics in boreal vole populations. Long and cold winters were neither a prerequisite for high-amplitude multiannual cycles, nor were mild winters with reduced snow cover associated with reduced winter growth rates. Population dynamics correlated more strongly with growing season than with winter conditions. Cyclicity was weakened by increasing growing season temperatures in the cold, but strengthened in the warm regions. High-amplitude multiannual vole cycles emerge in two climatic regimes: a winter-driven cycle in cold, and a summer-driven cycle in warm climates. Finally, we show that geographic climatic gradients alone may not

  19. Impact of the winter North Atlantic Oscillation (NAO) on the Western Pacific (WP) pattern in the following winter through Arctic sea ice and ENSO

    NASA Astrophysics Data System (ADS)

    Tachibana, Yoshihiro; Oshika, Miki; Nakamura, Tetsu

    2015-04-01

    This study tested the hypothesis that Asian weather and climate in a given winter can be predicted 1 year in advance. On the basis of a 51-year statistical analysis of reanalysis data, we propose for the first time that the positive phase of the Western Pacific (WP) pattern in the winter is linked to the negative phase of the North Atlantic Oscillation (NAO) in the previous winter, and vice versa. We show that there are two possible mechanisms responsible for this interannual remote linkage. One is an Arctic mechanism. Extensive Arctic sea ice in the summer after a negative NAO acts as a bridge to the positive phase of the WP in the next winter. The negative (positive) phase of the winter NAO changes oceanic currents in the North Atlantic and weakens (strengthens) oceanic heat transport into the Arctic. This weakened (strengthened) heat transport also slows down (speeds up) the reduction of sea ice in the spring. A condition of more (less) ice than normal then persists until the season of ice freezing in autumn. In winter, all of the Arctic Ocean is covered by sea ice, regardless of the autumn ice area. Less (more) ice production during the freezing season reduces (increases) the heat released from the ocean to the atmosphere in the Arctic. An anomalously small (large) heat flux excites stationary Rossby wave propagation, which induces warm (cold) advection to Japan. The other mechanism involves the tropics. An El Niño occurrence after a negative winter NAO acts as another bridge to the positive phase of the WP in the following winter. The timescale of the Arctic route is nearly decadal, whereas that of the tropical route is about 3-5 years. The tropical mechanism indicates that the NAO remotely excites an El Niño in the second half of the following year. A process perhaps responsible for the El Niño occurrence was investigated statistically. A negative NAO in the winter increases Eurasian snow cover. This anomalous snow cover then intensifies the cold air

  20. Cold stress and the cold pressor test.

    PubMed

    Silverthorn, Dee U; Michael, Joel

    2013-03-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This activity is easily adapted to an inquiry format that asks students to go to the scientific literature to learn about the test and then design a protocol for carrying out the test in classmates. The data collected are ideal for teaching graphical presentation of data and statistical analysis. PMID:23471256

  1. 1. VIEW SOUTHWARD FROM SOUTHWEST CORNER FRONT AND ARCH STREETS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW SOUTHWARD FROM SOUTHWEST CORNER FRONT AND ARCH STREETS (2. N. Front Street starts at left) - North Front Street Area Study, 2-66 North Front Street (Commercial Buildings), Philadelphia, Philadelphia County, PA

  2. Cold Weather Entomology.

    ERIC Educational Resources Information Center

    McLure, John W.

    1983-01-01

    Suggests instructional strategies and student activities related to the study of insects during the winter. Includes possible collecting sites and classroom activities once the insects have been collected. (JN)

  3. GOES Satellite Movie of 2014 Winter Storms

    NASA Video Gallery

    This new animation of NOAA's GOES-East satellite imagery shows the movement of winter storms from January 1 to March 24 making for a snowier-than-normal winter along the U.S. East coast and Midwest...

  4. Water masses, ocean fronts, and the structure of Antarctic seabird communities: putting the eastern Bellingshausen Sea in perspective

    USGS Publications Warehouse

    Ribic, Christine A.; Ainley, David G.; Ford, R. Glenn; Fraser, William R.; Tynan, Cynthia T.; Woehler, Eric J.

    2015-01-01

    Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April–September) and summer (October–March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins (Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group

  5. Water masses, ocean fronts, and the structure of Antarctic seabird communities: putting the eastern Bellingshausen Sea in perspective

    USGS Publications Warehouse

    Ribic, Christine A.; Ainley, David G.; Ford, R. Glenn; Fraser, William R.; Tynan, Cynthia T.; Woehler, Eric J.

    2011-01-01

    Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April–September) and summer (October–March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins (Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group

  6. Water masses, ocean fronts, and the structure of Antarctic seabird communities: Putting the eastern Bellingshausen Sea in perspective

    NASA Astrophysics Data System (ADS)

    Ribic, Christine A.; Ainley, David G.; Glenn Ford, R.; Fraser, William R.; Tynan, Cynthia T.; Woehler, Eric J.

    2011-07-01

    Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April-September) and summer (October-March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins ( Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group dominated

  7. Could Behaviour and Not Physiological Thermal Tolerance Determine Winter Survival of Aphids in Cereal Fields?

    PubMed Central

    Alford, Lucy; Andrade, Thiago Oliveira; Georges, Romain; Burel, Françoise; van Baaren, Joan

    2014-01-01

    Traits of physiological thermotolerance are commonly measured in the laboratory as predictors of the field success of ectotherms at unfavourable temperatures (e.g. during harsh winters, heatwaves, or under conditions of predicted global warming). Due to being more complicated to measure, behavioural thermoregulation is less commonly studied, although both physiology and behaviour interact to explain the survival of ectotherms. The aphids Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae are commercially important pests of temperate cereal crops. Although coexisting, these species markedly differ in winter success, with R. padi being the most abundant species during cold winters, followed by S. avenae and lastly M. dirhodum. To better understand the thermal physiology and behavioural factors contributing to differential winter success, the lethal temperature (physiological thermotolerance) and the behaviour of aphids in a declining temperature regime (behavioural thermotolerance) of these three species were investigated. Physiological thermotolerance significantly differed between the three species, with R. padi consistently the least cold tolerant and S. avenae the most cold tolerant. However, although the least cold tolerant of the study species, significantly more R. padi remained attached to the host plant at extreme sub-zero temperatures than S. avenae and M. dirhodum. Given the success of anholocyclic R. padi in harsh winters compared to its anholocyclic counterparts, this study illustrates that behavioural differences could be more important than physiological thermotolerance in explaining resistance to extreme temperatures. Furthermore it highlights that there is a danger to studying physiological thermotolerance in isolation when ascertaining risks of ectotherm invasions, the establishment potential of exotic species in glasshouses, or predicting species impacts under climate change scenarios. PMID:25490555

  8. Could behaviour and not physiological thermal tolerance determine winter survival of aphids in cereal fields?

    PubMed

    Alford, Lucy; Andrade, Thiago Oliveira; Georges, Romain; Burel, Françoise; van Baaren, Joan

    2014-01-01

    Traits of physiological thermotolerance are commonly measured in the laboratory as predictors of the field success of ectotherms at unfavourable temperatures (e.g. during harsh winters, heatwaves, or under conditions of predicted global warming). Due to being more complicated to measure, behavioural thermoregulation is less commonly studied, although both physiology and behaviour interact to explain the survival of ectotherms. The aphids Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae are commercially important pests of temperate cereal crops. Although coexisting, these species markedly differ in winter success, with R. padi being the most abundant species during cold winters, followed by S. avenae and lastly M. dirhodum. To better understand the thermal physiology and behavioural factors contributing to differential winter success, the lethal temperature (physiological thermotolerance) and the behaviour of aphids in a declining temperature regime (behavioural thermotolerance) of these three species were investigated. Physiological thermotolerance significantly differed between the three species, with R. padi consistently the least cold tolerant and S. avenae the most cold tolerant. However, although the least cold tolerant of the study species, significantly more R. padi remained attached to the host plant at extreme sub-zero temperatures than S. avenae and M. dirhodum. Given the success of anholocyclic R. padi in harsh winters compared to its anholocyclic counterparts, this study illustrates that behavioural differences could be more important than physiological thermotolerance in explaining resistance to extreme temperatures. Furthermore it highlights that there is a danger to studying physiological thermotolerance in isolation when ascertaining risks of ectotherm invasions, the establishment potential of exotic species in glasshouses, or predicting species impacts under climate change scenarios. PMID:25490555

  9. Light-Front Holographic QCD

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    The relation between the hadronic short-distance constituent quark and gluon particle limit and the long-range confining domain is yet one of the most challenging aspects of particle physics due to the strong coupling nature of Quantum Chromodynamics, the fundamental theory of the strong interactions. The central question is how one can compute hadronic properties from first principles; i.e., directly from the QCD Lagrangian. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time. Lattice numerical results follow from computation of frame-dependent moments of distributions in Euclidean space and dynamical observables in Minkowski spacetime, such as the time-like hadronic form factors, are not amenable to Euclidean lattice computations. The Dyson-Schwinger methods have led to many important insights, such as the infrared fixed point behavior of the strong coupling constant, but in practice, the analyses are limited to ladder approximation in Landau gauge. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. New theoretical tools are thus of primary interest for the interpretation of the results expected at the new mass scale and kinematic regions accessible to the JLab 12 GeV Upgrade Project. The AdS/CFT correspondence between gravity or string theory on a higher-dimensional anti-de Sitter (AdS) space and conformal field theories in physical space-time has led to a semiclassical approximation for strongly-coupled QCD, which provides physical insights into its nonperturbative dynamics. The correspondence is holographic in the sense that it determines a duality between theories in different number of space-time dimensions. This geometric approach leads in fact to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front

  10. Trends of cold and heat waves in Serbia

    NASA Astrophysics Data System (ADS)

    Unkašević, Miroslava; Tošić, Ivana

    2014-05-01

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

  11. Effects of weather on habitat selection and behavior of mallards wintering in Nebraska

    USGS Publications Warehouse

    Jorde, D.G.; Krapu, G.L.; Crawford, R.D.; Hay, M.A.

    1984-01-01

    Sex and age ratios, habitat selection, spatial characteristics, and time budgets of Mallards (Anas platyrhynchos) wintering on the Platte River in south central Nebraska were studied from mid-December to early April 1978-1980. The proportion of females and subadults in the population increased substantially from a cold to a mild winter. Radio-tagged Mallards shifted from riverine to canal roost sites during the coldest periods of the winter, seemingly because of more favorable microclimatic conditions there. Subadults ranged over larger areas during winter than did adults. Activity patterns varied with weather conditions, time of day, and habitat type. During cold periods, energetically costly activities such as aggression and courtship decreased at roost sites and the intensity of foraging activities in fields increased. Mallards were more active at riverine than canal sites during both years. High energy requirements and intense competition for scarce food appear to be primary factors limiting the northernmost distribution of Mallards in winter and causing their skewed sex and age ratios.

  12. Primary cold agglutinin disease.

    PubMed

    Mondal, Prabodh Chandra; Chakraborty, Partha Pratim; Bera, Mitali

    2011-07-01

    A 4-year-old girl presented with severe pallor and intermittent passage of cola-coloured urine. Routine investigations were suggestive of auto-immune haemolytic anaemia. Red cell agglutination was observed in peripheral smear and patient's serum was positive for cold agglutinins. Thorough work-up ruled out secondary cold agglutinin disease. Patient was treated successfully with corticosteroids. PMID:22315851

  13. Cold Sores (HSV-1)

    MedlinePlus

    ... Help a Friend Who Cuts? Cold Sores (HSV-1) KidsHealth > For Teens > Cold Sores (HSV-1) Print A A A Text Size What's in ... person's lips, are caused by herpes simplex virus-1 (HSV-1) . But they don't just show ...

  14. Liquid metal cold trap

    DOEpatents

    Hundal, Rolv

    1976-01-01

    A cold trap assembly for removing impurities from a liquid metal being provided with a hole between the incoming impure liquid metal and purified outgoing liquid metal which acts as a continuous bleed means and thus prevents the accumulation of cover gases within the cold trap assembly.

  15. Cold fusion research

    SciTech Connect

    1989-11-01

    I am pleased to forward to you the Final Report of the Cold Fusion Panel. This report reviews the current status of cold fusion and includes major chapters on Calorimetry and Excess Heat, Fusion Products and Materials Characterization. In addition, the report makes a number of conclusions and recommendations, as requested by the Secretary of Energy.

  16. How cold pool triggers deep convection?

    NASA Astrophysics Data System (ADS)

    Yano, Jun-Ichi

    2014-05-01

    The cold pool in the boundary layer is often considered a major triggering mechanism of convection. Here, presented are basic theoretical considerations on this issue. Observations suggest that cold pool-generated convective cells is available for shallow maritime convection (Warner et al. 1979; Zuidema et al. 2012), maritime deep convection (Barnes and Garstang 1982; Addis et al. 1984; Young et al. 1995) and continental deep convection (e.g., Lima and Wilson 2008; Flamant 2009; Lothon et al. 2011; Dione et al. 2013). Moreover, numerical studies appear to suggest that cold pools promote the organization of clouds into larger structures and thereby aid the transition from shallow to deep convection (Khairoutdinov and Randall 2006, Boing et al. 2012, Schlemmer and Hohenegger, 2014). Even a cold--pool parameterization coupled with convection is already proposed (Grandpeix and Lafore 2010: but see also Yano 2012). However, the suggested link between the cold pool and deep convection so far is phenomenological at the best. A specific process that the cold pool leads to a trigger of deep convection must still to be pinned down. Naively, one may imagine that a cold pool lifts up the air at the front as it propagates. Such an uplifting leads to a trigger of convection. However, one must realize that a shift of air along with its propagation does not necessarily lead to an uplifting, and even if it may happen, it would not far exceed a depth of the cold pool itself. Thus, the uplifting can never be anything vigorous. Its thermodynamic characteristics do help much either for inducing convection. The cold-pool air is rather under rapid recovering process before it can induce convection under a simple parcel-lifting argument. The most likely reason that the cold pool may induce convection is its gust winds that may encounter an air mass from an opposite direction. This induces a strong convergence, also leading to a strong uplifting. This is an argument essentially developed

  17. Field Demonstration of Automated Demand Response for Both Winter and Summer Events in Large Buildings in the Pacific Northwest

    SciTech Connect

    Piette, Mary Ann; Kiliccote, Sila; Dudley, Junqiao H.

    2011-11-11

    There are growing strains on the electric grid as cooling peaks grow and equipment ages. Increased penetration of renewables on the grid is also straining electricity supply systems and the need for flexible demand is growing. This paper summarizes results of a series of field test of automated demand response systems in large buildings in the Pacific Northwest. The objective of the research was two fold. One objective was to evaluate the use demand response automation technologies. A second objective was to evaluate control strategies that could change the electric load shape in both winter and summer conditions. Winter conditions focused on cold winter mornings, a time when the electric grid is often stressed. The summer test evaluated DR strategies in the afternoon. We found that we could automate both winter and summer control strategies with the open automated demand response communication standard. The buildings were able to provide significant demand response in both winter and summer events.

  18. Asymmetry in the response of central Eurasian winter temperature to AMO

    NASA Astrophysics Data System (ADS)

    Hao, Xin; He, Shengping; Wang, Huijun

    2015-12-01

    The asymmetry in the teleconnection of the central Eurasian winter surface air temperature (SAT) with the Atlantic multidecadal oscillation (AMO) is discussed using observations and model simulations. Observations indicate that the winter SAT over central Eurasia (30°-70°E, 30°-50°N) shows significant positive anomalies during the warm AMO period but weak and insignificant anomalies in the cold AMO period. In general, the warm winters in central Eurasia are associated with large-scale negative sea level pressure anomalies in Europe, anomalous southwesterly winds at 850 hPa over Europe, the "+ - +" geopotential height anomalies at 500 hPa in the south of Greenland, northern Europe, western Asia, and the slant north-south "+ -" pattern jet stream anomalies at 200 hPa in the north and south of the Caspian Sea. Reverse patterns occur during cold winters. These statistically significant features are observed in the warm phase of AMO. Reversed circulation anomalies are observed during the cold phase of AMO; however, these anomalies are weak and not statistically significant. Furthermore, the asymmetry in the atmospheric response to AMO is well supported by simulations with a suite of GFDL atmospheric model idealized experiments and four CMIP5 models historical experiments. Both observations and simulations indicate that Rossby waves propagating from the North Atlantic eastward to Eurasia emerge in the warm AMO and disappear in the cold AMO. Thus, the different propagations of Rossby waves, induced by the different surface thermal conditions of the warm and cold AMO, are the potential connection between the North Atlantic Ocean and central Eurasian climate, and may explain the asymmetry.

  19. Winter cover crops influence Amaranthus palmeri establishment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter cover crops were evaluated for their effect on Palmer amaranth (PA) suppression in cotton production. Cover crops examined included rye and four winter legumes: narrow-leaf lupine, crimson clover, Austrian winter pea, and cahaba vetch. Each legume was evaluated alone and in a mixture with rye...

  20. Attribution of UK Winter Floods to Anthropogenic Forcing

    NASA Astrophysics Data System (ADS)

    Schaller, N.; Alison, K.; Sparrow, S. N.; Otto, F. E. L.; Massey, N.; Vautard, R.; Yiou, P.; van Oldenborgh, G. J.; van Haren, R.; Lamb, R.; Huntingford, C.; Crooks, S.; Legg, T.; Weisheimer, A.; Bowery, A.; Miller, J.; Jones, R.; Stott, P.; Allen, M. R.

    2014-12-01

    Many regions of southern UK experienced severe flooding during the 2013/2014 winter. Simultaneously, large areas in the USA and Canada were struck by prolonged cold weather. At the time, the media and public asked whether the general rainy conditions over northern Europe and the cold weather over North America were caused by climate change. Providing an answer to this question is not trivial, but recent studies show that probabilistic event attribution is feasible. Using the citizen science project weather@home, we ran over 40'000 perturbed initial condition simulations of the 2013/2014 winter. These simulations fall into two categories: one set aims at simulating the world with climate change using observed sea surface temperatures while the second set is run with sea surface temperatures corresponding to a world that might have been without climate change. The relevant modelled variables are then downscaled by a hydrological model to obtain river flows. First results show that anthropogenic climate change led to a small but significant increase in the fractional attributable risk for 30-days peak flows for the river Thames. A single number can summarize the final result from probabilistic attribution studies indicating, for example, an increase, decrease or no change to the risk of the event occurring. However, communicating this to the public, media and other scientists remains challenging. The assumptions made in the chain of models used need to be explained. In addition, extreme events, like the UK floods of the 2013/2014 winter, are usually caused by a range of factors. While heavy precipitation events can be caused by dynamic and/or thermodynamic processes, floods occur only partly as a response to heavy precipitation. Depending on the catchment, they can be largely due to soil properties and conditions of the previous months. Probabilistic attribution studies are multidisciplinary and therefore all aspects need to be communicated properly.

  1. Progress in front propagation research

    NASA Astrophysics Data System (ADS)

    Fort, Joaquim; Pujol, Toni

    2008-08-01

    We review the progress in the field of front propagation in recent years. We survey many physical, biophysical and cross-disciplinary applications, including reduced-variable models of combustion flames, Reid's paradox of rapid forest range expansions, the European colonization of North America during the 19th century, the Neolithic transition in Europe from 13 000 to 5000 years ago, the description of subsistence boundaries, the formation of cultural boundaries, the spread of genetic mutations, theory and experiments on virus infections, models of cancer tumors, etc. Recent theoretical advances are unified in a single framework, encompassing very diverse systems such as those with biased random walks, distributed delays, sequential reaction and dispersion, cohabitation models, age structure and systems with several interacting species. Directions for future progress are outlined.

  2. Preventing cold-related morbidity and mortality in a changing climate

    PubMed Central

    Conlon, Kathryn C; Rajkovich, Nicholas B; White-Newsome, Jalonne L; Larsen, Larissa; Neill, Marie S O

    2011-01-01

    Winter weather patterns are anticipated to become more variable with increasing average global temperatures. Research shows that excess morbidity and mortality occurs during cold weather periods. We critically reviewed evidence relating temperature variability, health outcomes, and adaptation strategies to cold weather. Health outcomes included cardiovascular-, respiratory-, cerebrovascular-, and all-cause morbidity and mortality. Individual and contextual risk factors were assessed to highlight associations between individual- and neighborhood- level characteristics that contribute to a person’s vulnerability to variability in cold weather events. Epidemiologic studies indicate that the populations most vulnerable to variations in cold winter weather are the elderly, rural and, generally, populations living in moderate winter climates. Fortunately, cold-related morbidity and mortality are preventable and strategies exist for protecting populations from these adverse health outcomes. We present a range of adaptation strategies that can be implemented at the individual, building, and neighborhood level to protect vulnerable populations from cold-related morbidity and mortality. The existing research justifies the need for increased outreach to individuals and communities for education on protective adaptations in cold weather. We propose that future climate change adaptation research couple building energy and thermal comfort models with epidemiological data to evaluate and quantify the impacts of adaptation strategies. PMID:21592693

  3. Condensation Front Migration in a Protoplanetary Nebula

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.

    2004-01-01

    Condensation front dynamics are investigated in the mid-solar nebula region. A quasi-steady model of the evolving nebula is combined with equilibrium vapor pressure curves to determine evolutionary condensation fronts for selected species. These fronts are found to migrate inwards from the far-nebula to final positions during a period of 10(exp 7) years. The physical process governing this movement is a combination of local viscous heating and luminescent heating from the central star. Two luminescent heating models are used and their effects on the ultimate radial position of the condensation front are discussed. At first the fronts move much faster than the nebular accretion velocity, but after a time the accreting gas and dust overtakes the slowing condensation front.

  4. Front pinning in single vortex flows

    NASA Astrophysics Data System (ADS)

    Mahoney, John; Mitchell, Kevin

    2014-11-01

    We study fronts propagating in 2D fluid flows and show that there exist stable invariant front configurations for fairly generic flows. Here we examine the simple flow which combines a single vortex with an overall ``wind.'' We discuss how the invariant front can be derived from a simple 3D ODE. Existence of this front can then be understood in terms of bifurcations of fixed points, and the behavior of the invariant ``sliding front'' submanifold. Interestingly, the front bifurcation precedes the saddle-node bifurcation which gives rise to the vortex. This elementary structure has application in chemical reactor beds and laminar combustion in well-mixed fluids. We request that this talk follow the related talks by our collaborators Tom Solomon, Savannah Gowen, and Sarah Holler.

  5. Reaction front formation in contaminant plumes.

    PubMed

    Cribbin, Laura B; Winstanley, Henry F; Mitchell, Sarah L; Fowler, Andrew C; Sander, Graham C

    2014-12-15

    The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front. PMID:25461883

  6. Front propagation and rejuvenation in flipping processes

    SciTech Connect

    Ben-naim, Eli; Krapivsky, P I; Antal, T; Ben - Avrahm, D

    2008-01-01

    We study a directed flipping process that underlies the performance of the random edge simplex algorithm. In this stochastic process, which takes place on a one-dimensional lattice whose sites may be either occupied or vacant, occupied sites become vacant at a constant rate and simultaneously cause all sites to the right to change their state. This random process exhibits rich phenomenology. First, there is a front, defined by the position of the leftmost occupied site, that propagates at a nontrivial velocity. Second, the front involves a depletion zone with an excess of vacant sites. The total excess {Delta}{sub k} increases logarithmically, {Delta}{sub k} {approx_equal}ln k, with the distance k from the front. Third, the front exhibits ageing -- young fronts are vigorous but old fronts are sluggish. We investigate these phenomena using a quasi-static approximation, direct solutions of small systems and numerical simulations.

  7. Northern Front Range air quality study: Apportionment of carbonaceous particles

    SciTech Connect

    Fujita, E.M.; McDonald, J.D.; Hayes, T.L.; Zielinska, B.; Sagebiel, J.C.; Chow, J.C.; Watson, J.G.; Lawson, D.R.

    1998-12-31

    The Chemical Mass Balance (CMB) receptor model was applied to source profiles and ambient measurements taken during Winter 1997 at locations near Denver, CO. Chemical speciation included particulate and gaseous polycyclic aromatic hydrocarbons and other organic compounds (e.g., methoxylated phenols, hopanes, steranes, sterols, and lactones) in combination with inorganic particulate species and total elemental and organic carbon. Emissions were tested for more than 200 in-use vehicles, including heavy-duty trucks and buses, light-duty diesel vehicles and, smoking and high emitting gasoline vehicles. Separate profiles were obtained for light-duty vehicle for cold-start and hot stabilized modes. Wood burning and meat cooking emissions were also characterized. Motor vehicles account for about 85 percent of the ambient PM2.5 carbon in Denver and about 75 percent in areas north of Denver. Light-duty gasoline vehicles are the major sources of PM2.5 carbon in Denver, with cold starts (or high emitters) and smokers contributing about 30 percent each to PM2.5 carbon. Normal hot stabilized emissions and diesel exhaust contribute about 5 and 17 percent, respectively, and paved road dust contributes less than 5 percent. Smokers, and cold starts (or high emitters) are the largest contributors to PM2.5 organic carbon, and diesel exhaust, and cold starts (or high emitters) are the largest contributors to PM2.5 elemental carbon. PM2.5 emissions from the exhaust of light-duty gasoline vehicles are seriously underestimated in current inventories relative to diesel exhaust. Diesel exhaust, which is about two-thirds of the on-road vehicle PM2.5 emissions in the current inventory, account for only 18 percent according to the ambient source apportionment.

  8. Observations of seasonal subduction at the Iceland-Faroe Front

    NASA Astrophysics Data System (ADS)

    Beaird, N. L.; Rhines, P. B.; Eriksen, C. C.

    2016-06-01

    The polar front in the North Atlantic is bound to the ridge between Iceland and the Faroe Islands, where about one-half of the northward transport of warm Atlantic Water into the Nordic Seas occurs, as well as about one sixth of the equatorward dense overflow. We find a low salinity water mass at the surface of the Iceland-Faroe Front (IFF), which in wintertime subducts along outcropping isopycnals and is found in much modified form on the Atlantic side of the Iceland-Faroe Ridge (IFR) crest. The features found on the Atlantic side of the crest at depth have temperature and salinity characteristics which are clearly traceable to the surface outcrop of the IFF. The presence of coherent low salinity layers on the Atlantic side of the IFR crest has not been previously reported. Warm waters above the IFR primarily feed the Faroe Current, and injection of a low salinity water mass may play an early role in the water mass transformation taking place in the Nordic Seas. The seasonality of the intrusive features suggests a link between winter convection, mixed layer instability and deep frontal subduction. These low salinity anomalies (as well as a low oxygen water mass from the Iceland Basin) can be used as tracers of the intermediate circulation over the IFR.

  9. Muon front end for the neutrino factory

    NASA Astrophysics Data System (ADS)

    Rogers, C. T.; Stratakis, D.; Prior, G.; Gilardoni, S.; Neuffer, D.; Snopok, P.; Alekou, A.; Pasternak, J.

    2013-04-01

    In the neutrino factory, muons are produced by firing high-energy protons onto a target to produce pions. The pions decay to muons and pass through a capture channel known as the muon front end, before acceleration to 12.6 GeV. The muon front end comprises a variable frequency rf system for longitudinal capture and an ionization cooling channel. In this paper we detail recent improvements in the design of the muon front end.

  10. Hypothermia: A Cold Weather Hazard

    MedlinePlus

    ... Weather Hazard Heath and Aging Hypothermia: A Cold Weather Hazard What Are The Signs Of Hypothermia? Taking ... cold air. But, not everyone knows that cold weather can also lower the temperature inside your body. ...

  11. Ice-dependent winter survival of juvenile Atlantic salmon

    PubMed Central

    Hedger, R D; Næsje, T F; Fiske, P; Ugedal, O; Finstad, A G; Thorstad, E B

    2013-01-01

    Changes in snow and ice conditions are some of the most distinctive impacts of global warming in cold temperate and Arctic regions, altering the environment during a critical period for survival for most animals. Laboratories studies have suggested that reduced ice cover may reduce the survival of stream dwelling fishes in Northern environments. This, however, has not been empirically investigated in natural populations in large rivers. Here, we examine how the winter survival of juvenile Atlantic salmon in a large natural river, the River Alta (Norway, 70°N), is affected by the presence or absence of surface ice. Apparent survival rates for size classes corresponding to parr and presmolts were estimated using capture-mark-recapture and Cormack-Jolly-Seber models for an ice-covered and an ice-free site. Apparent survival (Φ) in the ice-covered site was greater than in the ice-free site, but did not depend on size class (0.64 for both parr and presmolt). In contrast, apparent survival in the ice-free site was lower for larger individuals (0.33) than smaller individuals (0.45). The over-winter decline in storage energy was greater for the ice-free site than the ice-covered site, suggesting that environmental conditions in the ice-free site caused a strong depletion in energy reserves likely affecting survival. Our findings highlight the importance of surface ice for the winter survival of juvenile fish, thus, underpinning that climate change, by reducing ice cover, may have a negative effect on the survival of fish adapted to ice-covered habitats during winter. PMID:23532172

  12. Deep Thermal Front (southeastern Brazilian coast) see through acoustics: a preliminary study from an operational oceanography perspective

    NASA Astrophysics Data System (ADS)

    Ponsoni, L.; Hermand, J.-P.; da Silveira, I. C. A.

    2012-04-01

    The continental shelf region off the southeastern Brazilian coast (between 20°S and 28°S) is characterized by intrusions of the relatively cold and fertile South Atlantic Central Water (SACW) from the open ocean. Prediction and monitoring of this water mass are topics of great interest given its importance, for example, on climate, carbon cycle, fishing, mariculture, nutrients and pollutants dispersion, and for the oil industry. The intersection of the 18°C isotherm with the seafloor is appointed in the literature as a good tracer for SACW presence on the continental shelf and also to characterize the Deep Thermal Front (DTF) [Castro, 1996]. Among different factors that drive the SACW penetration on the continental shelf, one prominent mechanism is the water transport driven by the conditions of NE-E wind forcing. These winds varies seasonally, and they are prevalent during the spring and summer months. During these months, the water column is generally stratified due the combined effects of solar heating and DTF presence. In contrast, the reverse effect is characteristic in winter, when the water column is nearly homogeneous, relatively colder on the surface and relatively warm close to the bottom. Consequently, the sound speed field changes and thus the acoustic rays are propagated with different characteristics depending on presence, absence or DTF position. Considering this information, acoustics may provide an additional source of data that supplements the other conventional methods (e.g., hydrographic moorings and cruises, buoys, gliders, and others) for tracking and monitoring the front movement. In addition, it is worth emphasizing that acoustic methods present one interesting advantage in that they are able to sample the water column over large three-dimensional distances on an effectively synoptic scale. In this paper, a preliminary study of acoustic propagation modelling through one vertical section off the Brazilian southeastern coast at Canan

  13. Interannual variation of East Asian Winter Monsoon and ENSO

    SciTech Connect

    Zhang, Yi; Sperber, Kenneth R.; Boyle, James S.

    1996-12-01

    This paper examines the interannual variation of the East Asian winter monsoon and its relationship with EJSO based on the 1979-1995 NCEP/NCAR reanalysis. Two stratifications of cold surges are used. The first one, described as the conventional cold surges, indicates that the surge frequency reaches a urn one year after El Nino events. The second one, originated from the same region as the first, is defined as the maximum wind events near the South China Sea. The variation of this stratification of surges is found to be in good agreement with the South Oscillation Index (SOI). Low SOI (high SOI) events coincide with years of low (high) surge frequency. The interannual variation of averaged meridional wind near the South China Sea and western Pacific is dominated by the South China Sea cold surges, and is also well correlated (R--O.82) with the SOI. Strong wind seasons are associated with La Nina and high SOI events; likewise, weak wind years are linked with El Nino and low SOI cases. This pattern is restricted north of the equator within the region of (OON-20 N, 11OOE-1300E), and is confined to the near surface layer. The surface Siberian high, 500 hPa trough and 200 hPa jetstream, all representing the large-scale monsoon flow, are found to be weaker than normal during El Nino years. In particular, the interannual variation of the Siberian high is in general agreement with the SOL.

  14. PBF Cooling Tower under construction. Cold water basin is five ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Cooling Tower under construction. Cold water basin is five feet deep. Foundation and basin walls are reinforced concrete. Camera facing west. Pipe openings through wall in front are outlets for return flow of cool water to reactor building. Photographer: John Capek. Date: September 4, 1968. INEEL negative no. 68-3473 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  15. Study of formation process of cold intermediate layer based on reanalysis of Black Sea hydrophysical fields for 1971-1993

    NASA Astrophysics Data System (ADS)

    Korotaev, G. K.; Knysh, V. V.; Kubryakov, A. I.

    2014-01-01

    A reanalysis of hydrophysical fields for 1971-1993 is used to study the formation mechanisms of the cold intermediate layer (CIL): the advective mechanism (associated with the advection of cold waters formed in the northwestern shelf (NWS)) and the convective mechanism (caused by wintertime convection inside cyclonic gyres in the central part of the sea). We consider the periods of alternating atmospheric conditions: the mild winter of 1980-1981, normal winter of 1987-1988, and cold winter of 1992-1993. Interannual features of replenishment and renewal of "old" CIL waters caused by these mechanisms are identified. In particular, cooled shelf waters sink along the continental slope and merge with "old" CIL waters during the mild winter of 1980-1981 more than 1 month later than during the cold winter 1992-1993 and more than 3 weeks later than during the normal winter of 1987-1988. The Sevastopol anticyclonic gyre and the northwest branch of the Black Sea Rim Current markedly influence the transformation of entrained cold NWS waters transported to the southwest and the central part of the water area. The local formation process of cold intermediate waters is found to be caused by the wintertime penetrating convection over domelike isosurfaces of temperature and salinity arising due to rising constant halocline (pycnocline) at the centers of cyclonic gyres because of the intensification of the wintertime circulation. Anomalously cold surface water, characterized by increased density, gradually sinks. An analysis of TS indices indicates that the transformed cold water spreads out over isopycnic surfaces with time, being entrained in cyclonic circulation and spreading throughout the sea, thus renewing "old" CIL waters.

  16. Communicating Certainty About Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, A.

    2013-12-01

    I have been spending much of my time in the past several years trying to warn the world about the continuing danger of nuclear weapons, and that the solution is a rapid reduction in the nuclear arsenal. I feel that a scientist who discovers dangers to society has an ethical duty to issue a warning, even if the danger is so scary that it is hard for people to deal with. The debate about nuclear winter in the 1980s helped to end the nuclear arms race, but the planet still has enough nuclear weapons, even after reductions planned for 2017 under the New START treaty, to produce nuclear winter, with temperatures plunging below freezing in the summer in major agricultural regions, threatening the food supply for most of the planet. New research by myself, Brian Toon, Mike Mills, and colleagues over the past six years has found that a nuclear war between any two countries, such as India and Pakistan, using 50 atom bombs each of the size dropped on Hiroshima could produce climate change unprecedented in recorded human history, and a world food crisis because of the agricultural effects. This is much less than 1% of the current global arsenal. Communicating certainty - what we know for sure - has been much more effective than communicating uncertainty. The limited success I have had has come from persistence and serendipity. The first step was to do the science. We have published peer-reviewed articles in major journals, including Science, Nature, Proceedings of the National Academy of Sciences, Journal of Geophysical Research, Atmospheric Chemistry and Physics, Physics Today, and Climatic Change. But policymakers do not read these journals. Through fairly convoluted circumstances, which will be described in this talk, we were able to get papers published in Scientific American and the Bulletin of Atomic Scientists. I have also published several encyclopedia articles on the subject. As a Lead Author of Chapter 8 (Radiative Forcing) of the recently published Fifth Assessment

  17. The Remarkable 2003-2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Krueger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

    2004-01-01

    The 2003-2004 Arctic winter was remarkable in the 40-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly two months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with two previous years, 1984-1985 and 1986-1987, with prolonged mid-winter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over two standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (seven in the past six years) is unprecedented. Lower stratospheric temperatures were unusually high during six of the past seven years, with five having much lower than usual potential for PSC formation and ozone loss (nearly none in 1998-1999, 2001-2002 and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of five of the last seven years with very low PSC potential would be expected to occur randomly once every approximately 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

  18. The Argentine ant persists through unfavorable winters via a mutualism facilitated by a native tree.

    PubMed

    Brightwell, Robert J; Silverman, Jules

    2011-10-01

    Mutualisms and facilitations can fundamentally change the relationship between an organism's realized and fundamental niche. Invasive species may prove particularly suitable models for investigating this relationship as many are dependent on finding new partners for successful establishment. We conducted field-based experiments testing whether a native tree facilitates the successful survival of the invasive Argentine ant, Linepithema humile (Mayr), through unfavorable winter conditions in the southeastern United States. We found Argentine ant nests aggregated around the native loblolly pine, Pinus taeda L., during the winter months. The bark of this tree absorbed enough radiant solar energy to reach temperatures suitable for Argentine ant foraging even when ambient temperatures should have curtailed all foraging. Conversely, foraging ceased when the trunk was shaded. The sun-warmed bark of this tree gave the Argentine ant access to a stable honeydew resource. Argentine ants were not found on or near deciduous trees even though bark temperatures were warm enough to permit Argentine ant foraging on cold winter days. Augmenting deciduous trees with sucrose water through the winter months lead to Argentine ant nests remaining at their base and Argentine ants foraging on the tree. The Argentine ant requires both foraging opportunity and a reliable winter food source to survive through unfavorable winter conditions in the southeastern United States. The loblolly pine provided both of these requirements extending the realized niche of Argentine ants beyond its fundamental niche. PMID:22251714

  19. Winter diversity and expression of proteorhodopsin genes in a polar ocean.

    PubMed

    Nguyen, Dan; Maranger, Roxane; Balagué, Vanessa; Coll-Lladó, Montserrat; Lovejoy, Connie; Pedrós-Alió, Carlos

    2015-08-01

    Mixotrophy is a valuable functional trait used by microbes when environmental conditions vary broadly or resources are limited. In the sunlit waters of the ocean, photoheterotrophy, a form of mixotrophy, is often mediated by proteorhodopsin (PR), a seven helices transmembrane protein binding the retinal chromophore. Altogether, they allow bacteria to capture photic energy for sensory and proton gradient formation cell functions. The seasonal occurrence and diversity of the gene coding for PR in cold oligotrophic polar oceans is not known and PR expression has not yet been reported. Here we show that PR is widely distributed among bacterial taxa, and that PR expression decreased markedly during the winter months in the Arctic Ocean. Gammaproteobacteria-like PR sequences were always dominant. However, within the second most common affiliation, there was a transition from Flavobacteria-like PR in early winter to Alphaproteobacteria-like PR in late winter. The phylogenetic shifts followed carbon dynamics, where patterns in expression were consistent with community succession, as identified by DNA community fingerprinting. Although genes for PR were always present, the trend in decreasing transcripts from January to February suggested reduced functional utility of PR during winter. Under winter darkness, sustained expression suggests that PR may continue to be useful for non-ATP forming functions, such as environmental sensing or small solute transport. The persistence of PR expression in winter among some bacterial groups may offer a competitive advantage, where its multifunctionality enhances microbial survival under harsh polar conditions. PMID:25700336

  20. Relations between winter 700-mb height anomalies and mass balance of South Cascade Glacier, Washington

    SciTech Connect

    McCabe, G.J.; Fountain, A.G.

    1995-12-31

    The yearly net mass balance of South Cascade Glacier, Washington, decreased during the mid-1970`s. Results show that the decrease is primarily caused by a significant decrease in the winter mass balance. The decrease in winter mass balance is caused, in part, by changes in winter mean atmospheric circulation that began during the mid-1970`s. Since the mid-1970`s, there has been an increase in winter mean atmospheric pressure over western Canada and the northern western contiguous US and a decrease in winter mean atmospheric pressure in the eastern North Pacific Ocean centered near the Aleutian islands. These changes in atmospheric circulation indicate a decrease in the movement of storms and moisture from the Pacific Ocean into the western contiguous US. In addition, the increase in atmospheric pressure over western Canada and the northern western contiguous US indicates an increase in subsidence, which results in a warming and drying of the air that further reduces precipitation and also increases the ratio of rain to snow during the cold season. These factors contribute to below-average winter mass balances.

  1. Interannual variability of winter eddy patterns in the eastern South China Sea

    NASA Astrophysics Data System (ADS)

    He, Yinghui; Xie, Jieshuo; Cai, Shuqun

    2016-05-01

    Merged altimetry data collected over 21 years are analyzed to study the interannual variability of winter eddy activities in the eastern South China Sea (SCS) associated with the El Niño-Southern Oscillation. Composite analyses of eddy probability reveal that a Luzon cold eddy (LCE) northwest of the Luzon Island, an anticyclonic eddy northwest of the Mindoro Island (referred as MAE) and a cyclonic eddy west of the Mindoro Island (referred as MCE) are common for winter. Further studies indicate that LCE and MAE weaken and MCE strengthens in El Niño winters, whereas data show the opposite behavior for La Niña winters. In addition, the geographical pattern of MAE and MCE in an El Niño winter is different from that in a La Niña winter. The interannual wind curl anomalies west of the Luzon and Mindoro Islands and the outflow from the SCS via the Mindoro Strait may be responsible for the interannual eddy variability.

  2. Effects of fluctuations on propagating fronts

    NASA Astrophysics Data System (ADS)

    Panja, Debabrata

    Propagating fronts are seen in varieties of nonequilibrium pattern forming systems in Physics, Chemistry and Biology. In the last two decades, many researchers have contributed to the understanding of the underlying dynamics of the propagating fronts. Of these, the deterministic and mean-field dynamics of the fronts were mostly understood in late 1980s and 1990s. On the other hand, although the earliest work on the effect of fluctuations on propagating fronts dates back to early 1980s, the subject of fluctuating fronts did not reach its adolescence until the mid 1990s. From there onwards the last few years witnessed a surge in activities in the effect of fluctuations on propagating fronts. Scores of papers have been written on this subject since then, contributing to a significant maturity of our understanding, and only recently a full picture of fluctuating fronts has started to emerge. This review is an attempt to collect all the works on fluctuating (propagating) fronts in a coherent and cogent manner in proper perspective. It is based on the idea of making our knowledge in this field available to a broader audience, and it is also expected to help to collect bits and pieces of loose thread-ends together for possible further investigation.

  3. Febrile/cold agglutinins

    MedlinePlus

    ... diagnose certain infections and find the cause of hemolytic anemia (a type of anemia that occurs when red ... or cold agglutinins can help explain why the hemolytic anemia is occurring and direct treatment.

  4. Improving the health forecasting alert system for cold weather and heat-waves in England: a case-study approach using temperature-mortality relationships

    NASA Astrophysics Data System (ADS)

    Masato, Giacomo; Cavany, Sean; Charlton-Perez, Andrew; Dacre, Helen; Bone, Angie; Carmicheal, Katie; Murray, Virginia; Danker, Rutger; Neal, Rob; Sarran, Christophe

    2015-04-01

    The health forecasting alert system for cold weather and heatwaves currently in use in the Cold Weather and Heatwave plans for England is based on 5 alert levels, with levels 2 and 3 dependent on a forecast or actual single temperature action trigger. Epidemiological evidence indicates that for both heat and cold, the impact on human health is gradual, with worsening impact for more extreme temperatures. The 60% risk of heat and cold forecasts used by the alerts is a rather crude probabilistic measure, which could be substantially improved thanks to the state-of-the-art forecast techniques. In this study a prototype of a new health forecasting alert system is developed, which is aligned to the approach used in the Met Office's (MO) National Severe Weather Warning Service (NSWWS). This is in order to improve information available to responders in the health and social care system by linking temperatures more directly to risks of mortality, and developing a system more coherent with other weather alerts. The prototype is compared to the current system in the Cold Weather and Heatwave plans via a case-study approach to verify its potential advantages and shortcomings. The prototype health forecasting alert system introduces an "impact vs likelihood matrix" for the health impacts of hot and cold temperatures which is similar to those used operationally for other weather hazards as part of the NSWWS. The impact axis of this matrix is based on existing epidemiological evidence, which shows an increasing relative risk of death at extremes of outdoor temperature beyond a threshold which can be identified epidemiologically. The likelihood axis is based on a probability measure associated with the temperature forecast. The new method is tested for two case studies (one during summer 2013, one during winter 2013), and compared to the performance of the current alert system. The prototype shows some clear improvements over the current alert system. It allows for a much greater

  5. Front end for GPS receivers

    NASA Technical Reports Server (NTRS)

    Thomas, Jr., Jess Brooks (Inventor)

    1999-01-01

    The front end in GPS receivers has the functions of amplifying, down-converting, filtering and sampling the received signals. In the preferred embodiment, only two operations, A/D conversion and a sum, bring the signal from RF to filtered quadrature baseband samples. After amplification and filtering at RF, the L1 and L2 signals are each sampled at RF at a high selected subharmonic rate. The subharmonic sample rates are approximately 900 MHz for L1 and 982 MHz for L2. With the selected subharmonic sampling, the A/D conversion effectively down-converts the signal from RF to quadrature components at baseband. The resulting sample streams for L1 and L2 are each reduced to a lower rate with a digital filter, which becomes a straight sum in the simplest embodiment. The frequency subsystem can be very simple, only requiring the generation of a single reference frequency (e.g. 20.46 MHz minus a small offset) and the simple multiplication of this reference up to the subharmonic sample rates for L1 and L2. The small offset in the reference frequency serves the dual purpose of providing an advantageous offset in the down-converted carrier frequency and in the final baseband sample rate.

  6. Stability of cosmological detonation fronts

    NASA Astrophysics Data System (ADS)

    Mégevand, Ariel; Membiela, Federico Agustín

    2014-05-01

    The steady-state propagation of a phase-transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.

  7. Stability of cosmological deflagration fronts

    NASA Astrophysics Data System (ADS)

    Mégevand, Ariel; Membiela, Federico Agustín

    2014-05-01

    In a cosmological first-order phase transition, bubbles of the stable phase nucleate and expand in the supercooled metastable phase. In many cases, the growth of bubbles reaches a stationary state, with bubble walls propagating as detonations or deflagrations. However, these hydrodynamical solutions may be unstable under corrugation of the interface. Such instability may drastically alter some of the cosmological consequences of the phase transition. Here, we study the hydrodynamical stability of deflagration fronts. We improve upon previous studies by making a more careful and detailed analysis. In particular, we take into account the fact that the equation of motion for the phase interface depends separately on the temperature and fluid velocity on each side of the wall. Fluid variables on each side of the wall are similar for weakly first-order phase transitions, but differ significantly for stronger phase transitions. As a consequence, we find that, for large enough supercooling, any subsonic wall velocity becomes unstable. Moreover, as the velocity approaches the speed of sound, perturbations become unstable on all wavelengths. For smaller supercooling and small wall velocities, our results agree with those of previous works. Essentially, perturbations on large wavelengths are unstable, unless the wall velocity is higher than a critical value. We also find a previously unobserved range of marginally unstable wavelengths. We analyze the dynamical relevance of the instabilities, and we estimate the characteristic time and length scales associated with their growth. We discuss the implications for the electroweak phase transition and its cosmological consequences.

  8. Connections Between Cold Air Pools and Mountain Valley Fog Events in Salt Lake City

    NASA Astrophysics Data System (ADS)

    Chachere, Catherine N.; Pu, Zhaoxia

    2016-05-01

    The aim of this study is to investigate the connection between cold air pools and fog events in Salt Lake City, Utah, United States. Statistical analyses are conducted using soundings and reported automated surface observing system data from Salt Lake International Airport for the last eighteen cold seasons (October to March, during 1997-2015). A Chi-square test of independence is performed on identified cold air pool, and fog events to determine whether the two events are correlated. Conditional probabilities are then computed to investigate the occurrence of fog, given the presence of a cold pool. These probabilities are compared against that of random fog generation in the mid-winter. It is concluded that the dependence between cold air pools and fog events is statistically significant. The presence of a cold pool makes the formation of fog more likely than random generation.

  9. Differential expression of proteins in response to molybdenum deficiency in winter wheat leaves under low-temperature stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum (Mo) is an essential micronutrient for plants. To obtain a better understanding of the molecular mechanisms of cold resistance enhanced by molybdenum application in winter wheat, we applied a proteomic approach to investigate the differential expression of proteins in response to molybden...

  10. Differences in vernalization duration requirement in soft winter wheat associated with variation at the vrn-B1 locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In winter wheat (Triticum aestivum L.), the timing of flowering initiation is governed by the action two main environmentally controlled group of genes; vernalization that defines a plant’s requirement for a prolonged exposure to cold temperatures and photoperiod sensitivity defining the need for a ...

  11. Seasonal and decadal variations of ice-shelf front positions in Dronning Maud Land, East Antarctica

    NASA Astrophysics Data System (ADS)

    Deschamps-Berger, César; Matsuoka, Kenichi; Moholdt, Geir; König, Max

    2015-04-01

    Most of recent rapid changes of the Antarctic ice sheet have been triggered from the ice shelves through enhanced basal melting and/or iceberg calving. The Dronning Maud Land (DML) coastal region is encompassed by many semi-continuous ice shelves, and its mass balance is thus particularly sensitive to changes in the coastal environment. Better knowledge on the region's ice shelves is necessary to predict future behavior of the ice sheet. Here, we present temporal changes of the ice-shelf front positions in DML over the past decade. RADARSAT-2 imagery was used to delineate the front positions at six times between August 2012 and December 2013. Displacements of the ice-shelf edges over this period are mostly in good agreement with displacements derived from satellite interferometery observations. Yet we observe in several sub-regions that displacement during the austral summer is larger than that during the winter. We also observe winter-growth of sea ice from the ice-shelf fronts and outwards to icebergs that are grounded on the continental shelf. Fast sea ice growth and break-up is seasonal and could influence ice-shelf flow close to the fronts. On a longer term, comparison between 2004 and 2009 MOA coast line datasets and our 2012-13 dataset highlights the general stability of the area in the past decade. Between 2004 and 2013, only six ice shelves experienced considerable retreat due to calving of tabular icebergs, leaving the remaining 90 % of the region's ice-shelf fronts advancing in accordance with their local flow.

  12. Shock front broadening in polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Barber, John; Kadau, Kai

    2008-03-01

    We analyze a model for the evolution of weak shock fronts (or elastic precursor waves) in polycrystalline materials. This model is based on the idea of Meyers and Carvalho [Mater. Sci. Eng. 24, 131 (1976)] that the shock velocity anisotropy within the polycrystal is the most important factor in shock front broadening. Our analysis predicts that the shock front width increases as the 1/2 power of the front penetration distance into the crystal. Our theoretical prediction is in plausible agreement with previous experimental results for the elastic precursor rise time, and it should therefore provide a useful shock width estimate. Furthermore, our theoretical framework is also applicable to other problems involving front propagation in heterogeneous media.

  13. Relativistic ionization fronts in gas jets

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Dias, J. M.; Gallacher, J. G.; Issac, R. C.; Fonseca, R. A.; Lopes, N. C.; Silva, L. O.; Mendonça, J. T.; Jaroszynski, D. A.

    2006-10-01

    A high-power ultra-short laser pulse propagating through a gas jet, ionizes the gas by tunnelling ionization, creating a relativistic plasma-gas interface. The relativistic ionization front that is created can be used to frequency up-shift electromagnetic radiation either in co-propagation or in counter-propagation configurations. In the counter-propagation configuration, ionization fronts can act as relativistic mirrors for terahertz radiation, leading to relativistic double Doppler frequency up-shift to the visible range. In this work, we identified and explored, the parameters that optimize the key features of relativistic ionization fronts for terahertz radiation reflection. The relativistic ionization front generated by a high power laser (TOPS) propagating in a supersonic gas jet generated by a Laval nozzle has been fully characterized. We have also performed detailed two-dimensional relativistic particle-in-cell simulations with Osiris 2.0 to analyze the generation and propagation of the ionization fronts.

  14. Comparison of the impact of the Arctic Oscillation and Eurasian teleconnection on interannual variation in East Asian winter temperatures and monsoon

    NASA Astrophysics Data System (ADS)

    Lim, Young-Kwon; Kim, Hae-Dong

    2016-04-01

    The large-scale impacts of the Arctic Oscillation (AO) and the Eurasian teleconnection (EU) on the East Asian winter climate are compared for the past 34 winters, focusing on (1) interannual monthly to seasonal temperature variability, (2) East Asian winter monsoon (EAWM), and (3) the Siberian high (SH) and cold surge. Regression analysis reveals warming by AO and cooling by EU over mid-latitude East Asia during their positive phase and vice versa (i.e., warm phase: +AO, -EU; cold phase: -AO, +EU). The EU impact was found to be comparable to the AO impact. For example, warm (cold) months during the warm (cold) AO phase are found clearly when the AO is in the same warm (cold) EU phase. No significant correlation was found between East Asian temperature and the AO when the warm (cold) AO coincided with the cold (warm) EU. The well-known relationship of strong (weak) SH during the cold (warm) AO phase was observed significantly more often when the AO was in the same cold (warm) EU phase. Also, the indices of EAWM, cold surge, and SH were more highly correlated with the EU than with the AO. The advective temperature change and associated circulation demonstrate that the large-scale field including the SH over the mid-latitude Asian inland is better represented by the EU, influencing the East Asian climate. These results suggest that the impact of EU should be considered more important than previously thought for a better understanding of East Asian winter temperature and monsoon variability.

  15. Seasonal variation in nutritional characteristics of the diet of greater white-fronted geese

    USGS Publications Warehouse

    Ely, C.R.; Raveling, D.G.

    2011-01-01

    We studied diet and habitat use of greater white-fronted geese (Anser albifrons) from autumn through spring on their primary staging and wintering areas in the Pacific Flyway, 1979-1982. There have been few previous studies of resource use and forage quality of wintering greater white-fronted geese in North America, and as a consequence there has been little empirical support for management practices pertaining to habitat conservation of this broadly distributed species. Observations of >2,500 flocks of geese and collections of foraging birds revealed seasonal and geographic variation in resource use reflective of changes in habitat availability, selection, and fluctuating physiological demands. Autumn migrants from Alaska arrived first in the Klamath Basin of California and southern Oregon, where they fed on barley, oats, wheat, and potatoes. Geese migrated from the Klamath Basin into the Central Valley of California in late autumn where they exploited agricultural crops rich in soluble carbohydrates, with geese in the Sacramento Valley feeding almost exclusively on rice and birds on the Sacramento-San Joaquin Delta primarily utilizing corn. White-fronted geese began their northward migration in late winter, and by early spring most had returned to the Klamath Basin where 37% of flocks were found in fields of new growth cultivated and wild grasses. Cereal grains and potatoes ingested by geese were low in protein (7-14%) and high in soluble nutrients (17-47% neutral detergent fiber [NDF]), whereas grasses were low in available energy (47-49% NDF) but high in protein (26-42%). Greater white-fronted geese are generalist herbivores and can exploit a variety of carbohydrate-rich cultivated crops, likely making these geese less susceptible to winter food shortages than prior to the agriculturalization of the North American landscape. However, agricultural landscapes can be extremely dynamic and may be less predictable in the long-term than the historic environments to

  16. Seasonal variation in nutritional characteristics of the diet of greater white-fronted geese

    USGS Publications Warehouse

    Ely, Craig R.; Raveling, Dennis G.

    2011-01-01

    We studied diet and habitat use of greater white-fronted geese (Anser albifrons) from autumn through spring on their primary staging and wintering areas in the Pacific Flyway, 1979-1982. There have been few previous studies of resource use and forage quality of wintering greater white-fronted geese in North America, and as a consequence there has been little empirical support for management practices pertaining to habitat conservation of this broadly distributed species. Observations of >2,500 flocks of geese and collections of foraging birds revealed seasonal and geographic variation in resource use reflective of changes in habitat availability, selection, and fluctuating physiological demands. Autumn migrants from Alaska arrived first in the Klamath Basin of California and southern Oregon, where they fed on barley, oats, wheat, and potatoes. Geese migrated from the Klamath Basin into the Central Valley of California in late autumn where they exploited agricultural crops rich in soluble carbohydrates, with geese in the Sacramento Valley feeding almost exclusively on rice and birds on the Sacramento-San Joaquin Delta primarily utilizing corn. White-fronted geese began their northward migration in late winter, and by early spring most had returned to the Klamath Basin where 37% of flocks were found in fields of new growth cultivated and wild grasses. Cereal grains and potatoes ingested by geese were low in protein (7-14%) and high in soluble nutrients (17-47% neutral detergent fiber [NDF]), whereas grasses were low in available energy (47-49% NDF) but high in protein (26-42%). Greater white-fronted geese are generalist herbivores and can exploit a variety of carbohydrate-rich cultivated crops, likely making these geese less susceptible to winter food shortages than prior to the agriculturalization of the North American landscape. However, agricultural landscapes can be extremely dynamic and may be less predictable in the long-term than the historic environments to

  17. The impact of the 2008 cold spell on mortality in Shanghai, China

    NASA Astrophysics Data System (ADS)

    Ma, Wenjuan; Yang, Chunxue; Chu, Chen; Li, Tiantian; Tan, Jianguo; Kan, Haidong

    2013-01-01

    No prior studies in China have investigated the health impact of cold spell. In Shanghai, we defined the cold spell as a period of at least seven consecutive days with daily temperature below the third percentile during the study period (2001-2009). Between January 2001 and December 2009, we identified a cold spell between January 27 and February 3, 2008 in Shanghai. We investigated the impact of cold spell on mortality of the residents living in the nine urban districts of Shanghai. We calculated the excess deaths and rate ratios (RRs) during the cold spell and compared these data with a winter reference period (January 6-9, and February 28 to March 2). The number of excess deaths during the cold spell period was 153 in our study population. The cold spell caused a short-term increase in total mortality of 13 % (95 % CI: 7-19 %). The impact was statistically significant for cardiovascular mortality (RR = 1.21, 95 % CI: 1.12-1.31), but not for respiratory mortality (RR = 1.14, 95 % CI: 0.98-1.32). For total mortality, gender did not make a statistically significant difference for the cold spell impact. Cold spell had a significant impact on mortality in elderly people (over 65 years), but not in other age groups. Conclusively, our analysis showed that the 2008 cold spell had a substantial effect on mortality in Shanghai. Public health programs should be tailored to prevent cold-spell-related health problems in the city.

  18. The low temperature response pathways for cold acclimation and vernalization are independent.

    PubMed

    Bond, Donna M; Dennis, Elizabeth S; Finnegan, E Jean

    2011-10-01

    Vernalization is the promotion of flowering in response to the prolonged cold of winter. To survive sub-zero winter temperatures, plants must first acclimate to low, non-freezing temperatures (cold acclimation). Induction of VERNALIZATION INSENSITIVE 3 (VIN3), the first gene in the vernalization pathway, is initiated within the same time frame as the induction of genes in the cold acclimation pathway raising the question of whether there are common elements in the signal transduction pathways that activate these two responses to cold. We show that none of the signalling components required for cold acclimation, including the 'master regulator'INDUCTION OF CBF EXPRESSION1 (ICE1) or HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE1 (HOS1), which has been described as a link between cold acclimation and vernalization, play a role in VIN3 induction. We also show that the hormone abscisic acid (ABA) does not modulate VIN3 induction, consistent with earlier reports that ABA signalling plays no role in the vernalization response. The cold acclimation pathway is activated at 12 °C, at which temperature there is no induction of VIN3 expression. Taken together, our data demonstrate that the responses to low temperatures leading to cold acclimation and vernalization are controlled by distinct signalling pathways. PMID:21631537

  19. The effect of ocean fronts on acoustic wave propagation in the Celtic Sea

    NASA Astrophysics Data System (ADS)

    Shapiro, G.; Chen, F.; Thain, R.

    2014-11-01

    Underwater noise is now classed as pollution in accordance with the Marine Strategy Framework Directive. Noise from shipping is a major contributor to the ambient noise levels in ocean, particularly at low (< 300 Hz) frequencies. This paper studies patterns and seasonal variations of underwater noise in the Celtic Sea by using a coupled ocean model (POLCOMS) and an acoustic model (HARCAM) in the year 2010. Two sources of sound are considered: (i) representing a typical large cargo ship and (ii) noise from pile-driving activity. In summer, when the source of sound is on the onshore side of the front, the sound energy is mostly concentrated in the near-bottom layer. In winter, the sound from the same source is distributed more evenly in the vertical. The difference between the sound level in summer and winter at 10 m depth is as high as 20 dB at a distance of 40 km. When the source of sound is on the seaward side of the front, the sound level is nearly uniform in the vertical. The transmission loss is also greater (~ 16 dB) in the summer than in the winter for shallow source while it is up to ~ 20 dB for deep source at 30 km.

  20. Tolerance to multiple climate stressors: a case study of Douglas-fir drought and cold hardiness.

    PubMed

    Bansal, Sheel; Harrington, Constance A; St Clair, John Bradley

    2016-04-01

    Drought and freeze events are two of the most common forms of climate extremes which result in tree damage or death, and the frequency and intensity of both stressors may increase with climate change. Few studies have examined natural covariation in stress tolerance traits to cope with multiple stressors among wild plant populations.We assessed the capacity of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), an ecologically and economically important species in the northwestern USA, to tolerate both drought and cold stress on 35 populations grown in common gardens. We used principal components analysis to combine drought and cold hardiness trait data into generalized stress hardiness traits to model geographic variation in hardiness as a function of climate across the Douglas-fir range.Drought and cold hardiness converged among populations along winter temperature gradients and diverged along summer precipitation gradients. Populations originating in regions with cold winters had relatively high tolerance to both drought and cold stress, which is likely due to overlapping adaptations for coping with winter desiccation. Populations from regions with dry summers had increased drought hardiness but reduced cold hardiness, suggesting a trade-off in tolerance mechanisms.Our findings highlight the necessity to look beyond bivariate trait-climate relationships and instead consider multiple traits and climate variables to effectively model and manage for the impacts of climate change on widespread species. PMID:27099710

  1. Tolerance to multiple climate stressors: A case study of Douglas-fir drought and cold hardiness

    USGS Publications Warehouse

    Bansal, Sheel; Harrington, Constance A; St. Clair, John Bradley

    2016-01-01

    Summary: 1. Drought and freeze events are two of the most common forms of climate extremes which result in tree damage or death, and the frequency and intensity of both stressors may increase with climate change. Few studies have examined natural covariation in stress tolerance traits to cope with multiple stressors among wild plant populations. 2. We assessed the capacity of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), an ecologically and economically important species in the northwestern USA, to tolerate both drought and cold stress on 35 populations grown in common gardens. We used principal components analysis to combine drought and cold hardiness trait data into generalized stress hardiness traits to model geographic variation in hardiness as a function of climate across the Douglas-fir range. 3. Drought and cold hardiness converged among populations along winter temperature gradients and diverged along summer precipitation gradients. Populations originating in regions with cold winters had relatively high tolerance to both drought and cold stress, which is likely due to overlapping adaptations for coping with winter desiccation. Populations from regions with dry summers had increased drought hardiness but reduced cold hardiness, suggesting a trade-off in tolerance mechanisms. 4. Our findings highlight the necessity to look beyond bivariate trait–climate relationships and instead consider multiple traits and climate variables to effectively model and manage for the impacts of climate change on widespread species.

  2. Immune responses to exercising in a cold environment.

    PubMed

    LaVoy, Emily C P; McFarlin, Brian K; Simpson, Richard J

    2011-12-01

    Cold temperature and exercise independently impose stress on the human body that can lead to circulatory and metabolic changes, and depress the immune system. Multiple stressors applied together may amplify this immunodepression, causing greater immune impairment and heightened infection risk than with either stressor alone. As such, winter athletes and other persons who work or physically exert themselves in cold temperatures may have greater levels of stress-induced immune impairment than would be expected under mild temperatures. This review examines the literature regarding changes to physiological and immunological parameters arising from exposure to cold temperatures and to exercise. Even brief exposure to cold leads to increased levels of norepinephrine and cortisol, lymphocytosis, decreased lymphoproliferative responses, decreased levels of TH1 cytokines and salivary IgA, and increased lactate levels during exercise. Whether these changes lead to increased susceptibility to infection, as suggested by some epidemiological reports, remains to be determined. Although there is some evidence that exercising in temperatures near 5°C leads to greater immune impairment compared to exercising in milder temperatures, there is a need to explore the effects of exercise on immunity in the subfreezing conditions typically encountered by winter athletes. This is required to fully determine the extent to which performing vigorous exercise in subfreezing temperatures amplifies exercise-induced immune impairment and infection risk. PMID:21982757

  3. Teaching in a Cold Environment.

    ERIC Educational Resources Information Center

    Ewert, Alan

    1979-01-01

    Designed to help teachers deal with students in a cold environment, this article explains cold physiology and fundamental laws of heat; describes 14 common cold injuries and their current treatment; and lists a number of useful teaching techniques for cold environments. (SB)

  4. Teaching in a Cold Environment.

    ERIC Educational Resources Information Center

    Ewert, Alan

    Instructors who teach outdoors in an environment so cold as to cause injury must satisfy program objectives while avoiding cold injury to themselves and students, help students focus on learning instead of discomfort, and alleviate some students' intense fear of the cold. Dealing with the cold successfully requires a thorough knowledge of:…

  5. Io in Front of Jupiter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope.

    Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet.

    This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel.

    The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.

    Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

  6. Front Range of the Rockies

    NASA Technical Reports Server (NTRS)

    2001-01-01

    These MISR images from May 12, 2001 (Terra orbit 7447) include portions of southern Wyoming, central Colorado, and western Nebraska. The top view is from the instrument's vertical-viewing (nadir) camera. The bottom image is a stereo 'anaglyph' generated using data from the nadir and 46-degree-forward cameras. Viewing the anaglyph with red/blue glasses (red filter over your left eye) gives a 3-D effect. To facilitate stereo viewing, the images have been oriented with north at the left. Each image measures 422 kilometers x 213 kilometers.

    The South Platte River enters just to the right of center at the top of the images. It wends its way westward (down), then turns southward (right) where it flows through the city of Denver. Located at the western edge of the Great Plains, Denver is nicknamed the 'Mile High City', a consequence of its 1609-meter (5280-foot) elevation above sea level. It shows up in the imagery as a grayish patch surrounded by numerous agricultural fields to the north and east. Denver is situated just east of the Front Range of the Rocky Mountains, located in the lower right of the images. The Rockies owe their present forms to tectonic uplift and sculpting by millions of years of erosion. Scattered cumulus clouds floating above the mountain peaks are visible in these images, and stand out most dramatically in the 3-D stereo view.

    To the north of Denver, other urban areas included within these images are Boulder, Greeley, Longmont, and Fort Collins, Colorado; Cheyenne and Laramie, Wyoming; and Scottsbluff, Nebraska.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

  7. Life on the front lines.

    PubMed

    Hern, W M

    1994-01-01

    Warren Hern's reminiscences about his experiences as medical director of the Boulder (Colorado) Abortion Clinic and as an abortion provider in private practice provide support for his statement, "Every doctor in America who does abortions lives under a death threat." Shortly after the clinic was opened, a group of anti-abortion physicians pressured the Boulder County Medical Society to pass a resolution declaring the clinic a "clear and present danger" that should be shut down by local health boards. As the only freestanding abortion clinic in the state in the mid-1970's, the Boulder center was targeted by the Right-to-Life Committee picketers and Dr. Hern was harassed in his home and in public. When Dr. Hern left the clinic a year later to establish a private practice specializing in pregnancy termination, the picketers followed. After release of a textbook he prepared on abortion practice, the publisher was deluged with hate mail and threats of boycott, leading them to withdraw the text from its list. Violent attacks on abortion clinics accelerated after Reagan's election and bullets were fired into Hern's waiting room. Randall Terry, national head of Operation Rescue, prayed for Hern's death at a rally in front of his clinic. By the time Dr. David Gunn was assassinated by an anti-abortionist in March 1993, there had been over 1285 acts of violence against abortion facilities and more than 100 facilities had been completely destroyed. The transgression for which Dr. Gunn was murdered was that he sought to save the lives and futures of countless women and support their right to become full participants in society. PMID:8186726

  8. Distribution patterns of American black duck and mallard winter band recoveries

    USGS Publications Warehouse

    Diefenbach, D.R.; Nichols, J.D.; Hines, J.E.

    1988-01-01

    We compared the distribution patterns of winter band recoveries of American black ducks (Anas rubripes) and mallards (A. platyrhynchos) banded in the same breeding areas. Young black ducks wintered northeast of young mallards but no differences in distribution patterns were detected between adult birds of the 2 species. Mallards exhibited greater temporal variation in distribution patterns and less fidelity to wintering areas. We speculate that these differences in distribution patterns are related to different behavioral responses by mallards and black ducks to variation in resource availability. Black ducks may reduce energy expenditure during periods of extreme cold and wait for conditions to improve, whereas mallards may migrate to areas that are warmer of where more food is available. The availability of quality habitat may be critical to the survival of black ducks during harsh weather conditions because of their relative lack of migrational flexibility, whereas mallards may be able to respond by migrating to favorable environments.

  9. Simulating the formation and fate of dense water in a midlatitude marginal sea during normal and warm winter conditions

    NASA Astrophysics Data System (ADS)

    Querin, Stefano; Cossarini, Gianpiero; Solidoro, Cosimo

    2013-02-01

    Dense shelf water production and the deep convection process in the Adriatic Sea are investigated, considering two case studies: the first is representative of the present climatic situation, whereas the second may be expected in a scenario characterized by mild winter conditions over the basin. Dense water production and spreading are studied using a high-resolution implementation of the Massachusetts Institute of Technology general circulation model that is initialized and forced with realistic conditions. This paper provides qualitative and quantitative information on mass transport, dense water pathways, thermohaline structures, and the mixing properties of the basin. In the northern Adriatic shelf, seawater temperature is the key element for winter dense water production because it contributes more relevantly than salinity in determining density. In the southern Adriatic Sea, a small amount of dense water that cascades directly into the pit can be formed on the narrow western shelf only during cold winter conditions. Moreover, open ocean deepwater formation occurs in the middle of the southern basin. In late winter and spring, although only when winter conditions have been sufficiently cold, northern Adriatic dense shelf water forms a subsurface stream of which the densest part rapidly sinks in the southern pit along the shelf break, whereas its lighter part flows southward and reaches the Otranto Strait. The frequent occurrence of mild winter conditions could lead to lower dense water production, with a reduced dense water flow from the Adriatic Sea to the Ionian Sea and a potential great impact on the eastern Mediterranean thermohaline circulation.

  10. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard

    PubMed Central

    Semenchuk, Philipp R; Elberling, Bo; Cooper, Elisabeth J

    2013-01-01

    Abstract The High Arctic winter is expected to be altered through ongoing and future climate change. Winter precipitation and snow depth are projected to increase and melt out dates change accordingly. Also, snow cover and depth will play an important role in protecting plant canopy from increasingly more frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5 years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas octopetala. However, the affected species were resilient and individuals did not experience any long term effects. In the case of short or cold summers, a subset of species suffered reduced reproductive success, which may affect future plant composition through possible cascading competition effects. Extreme winter warming events were shown to expose the canopy to cold winter air. The following summer most of the overwintering flower buds could not produce flowers. Thus reproductive success is reduced if this occurs in subsequent years. We conclude that snow depth influences flower abundance by altering season length and by protecting or exposing flower buds to cold winter air, but most species studied are resistant to changes. Winter warming events, often

  11. Climate Change Affects Winter Chill for Temperate Fruit and Nut Trees

    PubMed Central

    Luedeling, Eike; Girvetz, Evan H.; Semenov, Mikhail A.; Brown, Patrick H.

    2011-01-01

    Background Temperate fruit and nut trees require adequate winter chill to produce economically viable yields. Global warming has the potential to reduce available winter chill and greatly impact crop yields. Methodology/Principal Findings We estimated winter chill for two past (1975 and 2000) and 18 future scenarios (mid and end 21st century; 3 Global Climate Models [GCMs]; 3 greenhouse gas emissions [GHG] scenarios). For 4,293 weather stations around the world and GCM projections, Safe Winter Chill (SWC), the amount of winter chill that is exceeded in 90% of all years, was estimated for all scenarios using the “Dynamic Model” and interpolated globally. We found that SWC ranged between 0 and about 170 Chill Portions (CP) for all climate scenarios, but that the global distribution varied across scenarios. Warm regions are likely to experience severe reductions in available winter chill, potentially threatening production there. In contrast, SWC in most temperate growing regions is likely to remain relatively unchanged, and cold regions may even see an increase in SWC. Climate change impacts on SWC differed quantitatively among GCMs and GHG scenarios, with the highest GHG leading to losses up to 40 CP in warm regions, compared to 20 CP for the lowest GHG. Conclusions/Significance The extent of projected changes in winter chill in many major growing regions of fruits and nuts indicates that growers of these commodities will likely experience problems in the future. Mitigation of climate change through reductions in greenhouse gas emissions can help reduce the impacts, however, adaption to changes will have to occur. To better prepare for likely impacts of climate change, efforts should be undertaken to breed tree cultivars for lower chilling requirements, to develop tools to cope with insufficient winter chill, and to better understand the temperature responses of tree crops. PMID:21629649

  12. Cold moderators at ORNL

    SciTech Connect

    Lucas, A. T.

    1997-09-01

    The Advanced Neutron Source (ANS) cold moderators were not an 'Oak Ridge first', but would have been the largest both physically and in terms of cold neutron flux. Two cold moderators were planned each 410 mm in diameter and containing about 30L of liquid deuterium. They were to be completely independent of each other. A modular system design was used to provide greater reliability and serviceability. When the ANS was terminated, up–grading of the resident High Flux Isotope Reactor (HFIR) was examined and an initial study was made into the feasibility of adding a cold source. Because the ANS design was modular, it was possible to use many identical design features. Sub-cooled liquid at 4 bar abs was initially chosen for the HFIR design concept, but this was subsequently changed to 15 bar abs to operate above the critical pressure. As in the ANS, the hydrogen will operate at a constant pressure throughout the temperature range and a completely closed loop with secondary containment was adopted. The heat load of 2 kW made the heat flux comparable with that of the ANS. Subsequent studies into the construction of cryogenic moderators for the proposed new Synchrotron Neutron source indicated that again many of the same design concepts could be used. By connecting the two cold sources together in series, the total heat load of 2 kW is very close to that of the HFIR allowing a very similar supercritical hydrogen system to be configured. The two hydrogen moderators of the SNS provide a comparable heat load to the HFIR moderator. It is subsequently planned to connect the two in series and operate from a single cold loop system, once again using supercritical hydrogen. The spallation source also provided an opportunity to re-examine a cold pellet solid methane moderator operating at 20K.

  13. The hard winter of 1880-1881: Climatological context and communication via a Laura Ingalls Wilder narrative

    NASA Astrophysics Data System (ADS)

    Boustead, Barbara E.

    The Hard Winter of 1880-1881 was featured in the Laura Ingalls Wilder historical fiction account, The Long Winter, as well as in several town histories across the region. Both meteorological records and historical accounts indicate that the winter was particularly long, snowy, and cold. The question of how "hard" a winter is for a given location depends on the climatological context, which relies on an objective characterization of winter severity. The Accumulated Winter Season Severity Index (AWSSI) allows comparison of the winter of 1880-1881 among sites across the region, as well as in the context of the period of record, to quantify its severity. Additionally, investigating the impacts of both the El Nino/Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) in the central United States provides context for the influence of both a strongly negative NAO and an El Nino event during the winter of 1880-1881. With an understanding of the climatological factors influencing the Hard Winter, along with the context for its severity, a more thorough analysis then was conducted to quantify and describe its severity. The connection of the winter of 1880-1881 to a popular book written by an author who is a cultural icon provides a natural vehicle with which to communicate weather and climate concepts to multiple non-technical audiences. The communication of complex weather and climate concepts is a well-documented challenge. One method to bridge between science concepts and public understanding is to relate those concepts to familiar subjects and stories, including Laura Ingalls Wilder's books. A narrative constructed around the books, particularly The Long Winter, provides a means of audience engagement and interest in weather- and climate-related topics, which was at least partially quantified by surveying audiences of the narrative. Overall, the scientific background, combined with a familiar narrative voice, provides a means to transmit weather and

  14. Cosmic Pressure Fronts Mapped by Chandra

    NASA Astrophysics Data System (ADS)

    2000-03-01

    A colossal cosmic "weather system" produced by the collision of two giant clusters of galaxies has been imaged by NASA's Chandra X-ray Observatory. For the first time, the pressure fronts in the system can be traced in detail, and they show a bright, but relatively cool 50 million degree Celsius central region embedded in large elongated cloud of 70 million degree Celsius gas, all of which is roiling in a faint "atmosphere"of 100 million degree Celsius gas. "We can compare this to an intergalactic cold front," said Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. and leader of the international team involved in the analysis of the observations. "A major difference is that in this case, cold means 70 million degree Celsius." The gas clouds are in the core of a galaxy cluster known as Abell 2142. The cluster is six million light years across and contains hundreds of galaxies and enough gas to make a thousand more. It is one of the most massive objects in the universe. Galaxy clusters grow to vast sizes as smaller clusters are pulled inward under the influence of gravity. They collide and merge over the course of billions of years, releasing tremendous amounts of energy that heats the cluster gas to 100 million degrees Celsius. The Chandra data provides the first detailed look at the late stages of this merger process. Previously, scientists had used the German-US Roentgensatellite to produce a broad brush picture of the cluster. The elongated shape of the bright cloud suggested that two clouds were in the process of coalescing into one, but the details remained unclear. Chandra is able to measure variations of temperature, density, and pressure with unprecedented resolution. "Now we can begin to understand the physics of these mergers, which are among the most energetic events in the universe," said Markevitch. "The pressure and density maps of the cluster show a sharp boundary that can only exist in the moving environment of a

  15. Nutrient dynamics in the winter thermohaline frontal zone of the northern shelf region of the South China Sea

    NASA Astrophysics Data System (ADS)

    Liu, Su Mei; Guo, Xinyu; Chen, Qi; Zhang, Jing; Bi, Yan Feng; Luo, Xin; Li, Jian Bing

    2010-11-01

    As the first attempt to estimate the nutrient transport across the winter thermohaline frontal zone on the northern shelf of the South China Sea, the nutrient dynamics around the front and the effects of cross-frontal water exchange on nutrient transport were investigated using wintertime field observations. Both water temperature and salinity increased from coastal to oceanic waters, showing the presence of a thermohaline front. The concentrations of dissolved inorganic nutrients decreased oceanward, especially across the thermohaline front, while those of dissolved organic nutrients (i.e., dissolved organic nitrogen (DON) and dissolved organic phosphorus) showed patchy distributions. Ammonium was the major constituent of dissolved inorganic nitrogen, and DON was the main component of total dissolved nitrogen. Molar ratios of PO43-/total dissolved phosphorus decreased from coastal to oceanic waters, indicating that PO43- was rapidly removed and/or consumed from the water column and that organic matter degradation increased offshore, replenishing PO43-. Molar ratios of NO3-/(NH4+ + DON) were 0.01-0.6, indicating dominance of regenerated nitrogen. Surface water convergence and bottom water divergence were identified in the across-shore velocity field, and the calculated across-shore nutrient fluxes suggest that the presence of the winter thermohaline front promotes the offshore transport of nutrients from coastal waters. The transport path begins with convergence of surface coastal waters toward the front, followed by the sinking in the frontal region and the oceanward movement through the bottom layer of the front offshore side. With an assumption of 500 km as the length of thermohaline front on the northern shelf of the South China Sea, the calculated offshore fluxes of nutrients across the entire front are larger than those from the Zhujiang (Pearl River) and the Changjiang (Yangtze River).

  16. COLD WEATHER PLUME STUDY

    EPA Science Inventory

    While many studies of power plant plume transport and transformation have been performed during the summer, few studies of these processes during the winter have been carried out. Accordingly, the U.S. Environmental Protection Agency and the Electric Power Research Institute join...

  17. Distribution and diurnal behavior of Steller's Eiders wintering on the Alaska Peninsula

    USGS Publications Warehouse

    Laubhan, M.K.; Metzner, K.A.

    1999-01-01

    We studied the distribution and activities of adult Steller's Eiders (Polysticta stelleri) during winter and spring on a deep-water embayment and a shallow lagoon along the Alaska Peninsula from September 1980 to May 1981. During the remigial molt, eiders were observed on Izembek Lagoon but not on Cold Bay. Following the flightless period, Izembek Lagoon continued to support 63-100% of eiders encountered during surveys. As ice cover on Izembek Lagoon increased, the number of birds decreased on Izembek Lagoon but increased on Cold Bay, suggesting that some eiders disperse to nearshore, deep-water habitats in close proximity to Izembek Lagoon during severe weather. Diurnal activity budgets indicated that the amount of time resting or engaged in aggression and alert activities was similar among locations, seasons, tidal stages, and sexes. In contrast, time spent foraging differed among seasons and locations but did not differ among tidal stages or sexes. Although time spent foraging was similar during winter and spring on Izembek Lagoon, eiders on Cold Bay foraged more during winter compared to spring. Synchronous diving was the dominant foraging strategy.

  18. Winter warming from large volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Robock, Alan; Mao, Jianping

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95-percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  19. Winter warming from large volcanic eruptions

    SciTech Connect

    Robock, A.; Mao, J.

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  20. Winter leaf reddening in 'evergreen' species.

    PubMed

    Hughes, Nicole M

    2011-05-01

    Leaf reddening during autumn in senescing, deciduous tree species has received widespread attention from the public and in the scientific literature, whereas leaf reddening in evergreen species during winter remains largely ignored. Winter reddening can be observed in evergreen herbs, shrubs, vines and trees in Mediterranean, temperate, alpine, and arctic regions, and can persist for several months before dissipating with springtime warming. Yet, little is known about the functional significance of this colour change, or why it occurs in some species but not others. Here, the biochemistry, physiology and ecology associated with winter leaf reddening are reviewed, with special focus on its possible adaptive function. Photoprotection is currently the favoured hypothesis for winter reddening, but alternative explanations have scarcely been explored. Intraspecific reddening generally increases with sunlight incidence, and may also accompany photosynthetic inferiority in photosynthetically 'weak' (e.g. low-nitrogen) individuals. Red leaves tend to show symptoms of shade acclimation relative to green, consistent with a photoprotective function. However, winter-red and winter-green species often cohabitate the same high-light environments, and exhibit similar photosynthetic capacities. The factors dictating interspecific winter leaf colouration therefore remain unclear. Additional outstanding questions and future directions are also highlighted, and possible alternative functions of winter reddening discussed. PMID:21375534

  1. Assessing the Geomorphic Evolution and Hydrographic Changes Induced by Winter Storms along the Louisiana Coast

    NASA Technical Reports Server (NTRS)

    Menzel, W. Paul; Moeller, Christopher, C; Huh, Oscar K.; Roberts, Harry H.

    1998-01-01

    The influence that cold front passages have on Louisiana coastal environments, including land loss and land building processes, has been the primary topic of this multidisciplinary research. This research has combined meteorological, remote sensing, and coastal expertise from the University of Wisconsin (UW) and Louisiana State University (LSU). Analyzed data sets include remotely sensed radiometric data (AVHRR on NOAA-12,13,14, Multispectral Atmospheric Mapping Sensor (MAMS) and MODIS Airborne Simulator (MAS) on NASA ER-2), U.S. Army Corps of Engineers (USACE) water level data, water quality data from the Coastal Studies Institute (CSI) at LSU, USACE river discharge data, National Weather Service (NWS) and CSI wind in sitzi measurements, geomorphic measurements from aerial photography (NASA ER-2 and Learjet), and CSI ground based sediment burial pipes (for monitoring topographic change along the Louisiana coast) and sediment cores. The work reported here-in is a continuation of an initial investigation into coastal Louisiana landform modification by cold front systems. That initial effort demonstrated the importance of cold front winds in the Atchafalaya Bay sediment plume distribution (Moeller et al.), documented the sediment transport and deposition process of the western Louisiana coast (Huh et al.) and developed tools (e.g. water types identification, suspended solids estimation) from multispectral radiometric data for application to the current study. This study has extended that work, developing a Geomorphic Impact Index (GI(sup 2)) for relating atmospheric forcing to coastal response and new tools to measure water motion and sediment transport.

  2. "Cold training" affects rat liver responses to continuous cold exposure.

    PubMed

    Venditti, Paola; Napolitano, Gaetana; Barone, Daniela; Di Meo, Sergio

    2016-04-01

    Continuous exposure of homeothermic animals to low environmental temperatures elicits physiological adaptations necessary for animal survival, which are associated to higher generation of pro-oxidants in thermogenic tissues. It is not known whether intermittent cold exposure (cold training) is able to affect tissue responses to continuous cold exposure. Therefore, we investigated whether rat liver responses to continuous cold exposure of 2 days are modified by cold training (1h daily for 5 days per week for 3 consecutive weeks). Continuous cold increased liver oxidative metabolism by increasing tissue content of mitochondrial proteins and mitochondrial aerobic capacity. Cold training did not affect such parameters, but attenuated or prevented the changes elicited by continuous cold exposure. Two-day cold exposure increased lipid hydroperoxide and protein-bound carbonyl levels in homogenates and mitochondria, whereas cold training decreased such effects although it decreased only homogenate protein damage in control rats. The activities of the antioxidant enzymes GPX and GR and H2O2 production were increased by continuous cold exposure. Despite the increase in GPX and GR activities, livers from cold-exposed rats showed increased susceptibility to in vitro oxidative challenge. Such cold effects were decreased by cold training, which in control rats reduced only H2O2 production and susceptibility to stress. The changes of PGC-1, NRF-1, and NRF-2 expression levels were consistent with those induced by cold exposure and cold training in mitochondrial protein content and antioxidant enzyme activities. However, the mechanisms by which cold training attenuates the effects of the continuous cold exposure remain to be elucidated. PMID:26808664

  3. Xanthophyll cycle pigment and antioxidant profiles of winter-red (anthocyanic) and winter-green (acyanic) angiosperm evergreen species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaves of many angiosperm evergreen species turn red during winter, corresponding with synthesis of anthocyanin pigments. The function of winter color change, and why it occurs in some species and not others, is not yet understood. We hypothesized that anthocyanins play a compensatory photoprotect...

  4. Warmer winters modulate life history and energy storage but do not affect sensitivity to a widespread pesticide in an aquatic insect.

    PubMed

    Arambourou, Hélène; Stoks, Robby

    2015-10-01

    Despite the increased attention for the effects of pesticides under global warming no studies tested how winter warming affects subsequent sensitivity to pesticides. Winter warming is expected to cause delayed negative effects when it increases metabolic rates and thereby depletes energy reserves. Using a common-garden experiment, we investigated the combined effect of a 4 °C increase in winter temperature and subsequent exposure to chlorpyrifos in the aquatic larvae of replicated low- and high-latitude European populations of the damselfly Ischnura elegans. The warmer winter (8 °C) resulted in a higher winter survival and higher growth rates compared to the cold winter (4 °C) commonly experienced by European high-latitude populations. Low-latitude populations were better at coping with the warmer winter, indicating thermal adaptation to the local winter temperatures. Subsequent chlorpyrifos exposure at 20 °C induced strong negative effects on survival, growth rate, lipid content and acetylcholinesterase activity while phenoloxidase activity increased. These pesticide effects were not affected by winter warming. Our results suggest that for species where winter warming has positive effects on life history, no delayed effects on the sensitivity to subsequent pesticide exposure should be expected. PMID:26261878

  5. Marine fronts at the continental shelves of austral South America - Physical and ecological processes

    NASA Astrophysics Data System (ADS)

    Acha, Eduardo M.; Mianzan, Hermes W.; Guerrero, Raúl A.; Favero, Marco; Bava, José

    2004-01-01

    Neritic fronts are very abundant in austral South America, covering several scales of space and time. However, this region is poorly studied from a systemic point of view. Our main goal is to develop a holistic view of physical and ecological patterns and processes at austral South America, regarding frontal arrangements. Satellite information (sea surface temperature and chlorophyll concentration), and historical hydrographic data were employed to show fronts. We compiled all existing evidence (physical and biological) about fronts to identify regions defined by similar types of coastal fronts and to characterize them. Fronts in austral South America can be arranged in six zones according to their location, main forcing, key physical variables, seasonality, and enrichment mechanisms. Four zones, the Atlantic upwelling zone; the temperate estuarine zone; the Patagonian tidal zone and the Argentine shelf-break zone, occupy most of the Atlantic side. The Chile-Peru upwelling zone, on the Pacific, is the largest and best-known region. The Patagonian cold estuarine zone encompasses the tip of South America, connecting the Pacific and Atlantic oceans, and remains poorly studied. When observed at a continental scale, the Pacific coast dominated by two large frontal zones appears simplest than the Atlantic coast in terms of frontal richness. The extension of the continental shelf in the Atlantic coast allows for the development of a great diversity of mesoscale fronts. Though frontal zones we defined are extensive areas of the continental shelves, fronts inside the zones are comparatively small areas. Even so, they play a paramount role in ecological processes, allowing for high biological production; offering feeding and/or reproductive habitats for fishes, squids, and birds; acting as retention areas for larvae of benthic species; and promoting establishment of benthic invertebrates that benefit from the organic production in the frontal area.

  6. Massive cold cloud clusters

    NASA Astrophysics Data System (ADS)

    Toth, L. Viktor; Marton, Gabor; Zahorecz, Sarolta

    2015-08-01

    The all-sky Planck catalogue of Galactic Cold Clumps (PGCC, Planck 2015 results XXVIII 2015) allows an almost unbiased study of the early phases of star-formation in our Galaxy. Several thousand of the clumps have also distance estimates allowing a mass, and density determination. The nature of Planck clumps varies from IRDCs to tiny nearby cold clouds with masses ranging from one to several tens of thousands solar masses. Some of the clumps are embedded in GMCs, others are isolated. Some are close or even very close to OB associations, while others lay far from any UV luminous objects.The small scale clustering of these objects was studied with the improved Minimum Spanning Tree method of Cartwright & Whitworth identifying groups in 3D space. As a result also massive cold cloud clusters were identified. We analyse the MST structures, and discuss their relation to ongoing and future massive star formation.

  7. Cold-responsive gene regulation during cold acclimation in plants.

    PubMed

    Lissarre, Mickael; Ohta, Masaru; Sato, Aiko; Miura, Kenji

    2010-08-01

    Regulation of the transcriptome is necessary for plants to acquire cold tolerance, and cold induces several genes via a cold signaling pathway. The transcription factors CBF/DREB1 (C-repeat binding factor/dehydration responsive element binding1) and ICE1 (inducer of CBF expression1) have important roles in the regulation of cold-responsive gene expression. ICE1 is post-translationally regulated by ubiquitylation-mediated proteolysis and sumoylation. This mini-review highlights some recent studies on plant cold signaling. The relationships among cold signaling, salicylic acid accumulation and stomatal development are also discussed. PMID:20699657

  8. Automatic detection of low altitude wind shear due to gust fronts in the terminal Doppler weather radar operational demonstration

    NASA Technical Reports Server (NTRS)

    Klingle-Wilson, Diana

    1990-01-01

    A gust front is the leading edge of the cold air outflow from a thunderstorm. Wind shears and turbulence along the gust front may produce potentially hazardous conditions for an aircraft on takeoff or landing such that runway operations are significantly impacted. The Federal Aviation Administration (FAA) has therefore determined that the detection of gust fronts in the terminal environment be an integral part of the Terminal Doppler Weather Radar (TDWR) system. Detection of these shears by the Gust Front Algorithm permits the generation of warnings that can be issued to pilots on approach and departure. In addition to the detection capability, the algorithm provides an estimate of the wind speed and direction following the gust front (termed wind shift) and the forecasted location of the gust front up to 20 minutes before it impacts terminal operations. This has shown utility as a runway management tool, alerting runway supervisors to approaching wind shifts and the possible need to change runway configurations. The formation and characteristics of gust fronts and their signatures in Doppler radar data are discussed. A brief description of the algorithm and its products for use by Air Traffic Control (ATC), along with an assessment of the algorithm's performance during the 1988 Operational Test and Evaluation, is presented.

  9. Heat conduction fronts in planetary nebulae

    NASA Technical Reports Server (NTRS)

    Soker, Noam

    1994-01-01

    We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

  10. Front-End Analysis Cornerstone of Logistics

    NASA Technical Reports Server (NTRS)

    Nager, Paul J.

    2000-01-01

    The presentation provides an overview of Front-End Logistics Support Analysis (FELSA), when it should be performed, benefits of performing FELSA and why it should be performed, how it is conducted, and examples.

  11. On the stability of subsonic thermal fronts

    SciTech Connect

    Ibanez S, Miguel H.; Shchekinov, Yuri; Bessega L, Maria C.

    2005-08-15

    The stability of subsonic thermal fronts against corrugation is analyzed and an exact dispersion relation is obtained taking into account the compressibility of the gas. For heat fronts, this dispersion equation has an unstable root ({omega}{sub ex}) corresponding to the Landau-Darrieus unstable mode ({omega}{sub 0}) modified by the compressional effects. In particular, the exact solution shows a conspicuous maximum very close to the value of the intake Mach number M{sub 1} at which a Chapman-Jouguet deflagration wave behind the heat front is formed. Cooling fronts are stable for corrugation-like disturbances. A maximum damping as well as a maximum in the frequency occur at a value of M{sub 1} depending on the value of the normalized cooling q.

  12. Coarsening to chaos-stabilized fronts

    NASA Astrophysics Data System (ADS)

    Poon, Ka-Fai; Wittenberg, Ralf W.

    2011-01-01

    We investigate a model for pattern formation in the presence of Galilean symmetry proposed by Matthews and Cox [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.62.R1473 62, R1473 (2000)], which has the form of coupled generalized Burgers- and Ginzburg-Landau-type equations. With only the system size L as a parameter, we find distinct “small-L” and “large-L” regimes exhibiting clear differences in their dynamics and scaling behavior. The long-time statistically stationary state contains a single L-dependent front, stabilized globally by spatiotemporally chaotic dynamics confined away from the front. For sufficiently large domains, the transient dynamics include a state consisting of several viscous shocklike structures that coarsens gradually, before collapsing to a single front when one front absorbs the others.

  13. Nonperturbative light-front Hamiltonian methods

    NASA Astrophysics Data System (ADS)

    Hiller, J. R.

    2016-09-01

    We examine the current state-of-the-art in nonperturbative calculations done with Hamiltonians constructed in light-front quantization of various field theories. The language of light-front quantization is introduced, and important (numerical) techniques, such as Pauli-Villars regularization, discrete light-cone quantization, basis light-front quantization, the light-front coupled-cluster method, the renormalization group procedure for effective particles, sector-dependent renormalization, and the Lanczos diagonalization method, are surveyed. Specific applications are discussed for quenched scalar Yukawa theory, ϕ4 theory, ordinary Yukawa theory, supersymmetric Yang-Mills theory, quantum electrodynamics, and quantum chromodynamics. The content should serve as an introduction to these methods for anyone interested in doing such calculations and as a rallying point for those who wish to solve quantum chromodynamics in terms of wave functions rather than random samplings of Euclidean field configurations.

  14. 33 CFR 100.109 - Winter Harbor Lobster Boat Race, Winter Harbor, ME.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Winter Harbor Lobster Boat Race, Winter Harbor, ME. 100.109 Section 100.109 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Lobster Boat Race, Winter Harbor, ME. (a) Regulated area. The regulated area includes all waters of...

  15. Introducing winter canola to the winter wheat-fallow region of the Pacific Northwest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growers in the low-rainfall, winter wheat-fallow region of the Pacific Northwest are in need of an alternative crop to diversify their markets, manage pests, and increase wheat yields. Winter canola may be a viable crop option for growers in the region. However, agronomic research for winter canol...

  16. Induction of DREB2A pathway with repression of E2F, Jasmonic acid biosynthetic and photosynthesis pathways in cold acclimation specific freeze resistant wheat crown

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter wheat lines can achieve cold acclimation (development of tolerance to freezing temperatures) and vernalization (delay in transition from vegetative to reproductive phase) in response to low non-freezing temperatures. To describe cold acclimation specific processes and pathways, we utilized co...

  17. Immunolocalization of Antifreeze Proteins in Winter Rye Leaves, Crowns, and Roots by Tissue Printing.

    PubMed Central

    Antikainen, M.; Griffith, M.; Zhang, J.; Hon, W. C.; Yang, DSC.; Pihakaski-Maunsbach, K.

    1996-01-01

    During cold acclimation, antifreeze proteins (AFPs) that are similar to pathogenesis-related proteins accumulate in the apoplast of winter rye (Secale cereale L. cv Musketeer) leaves. AFPs have the ability to modify the growth of ice. To elucidate the role of AFPs in the freezing process, they were assayed and immunolocalized in winter rye leaves, crowns, and roots. Each of the total soluble protein extracts from cold-acclimated rye leaves, crowns, and roots exhibited antifreeze activity, whereas no antifreeze activity was observed in extracts from nonacclimated rye plants. Antibodies raised against three apoplastic rye AFPs, corresponding to a glucanase-like protein (GLP, 32 kD), a chitinase-like protein (CLP, 35 kD), and a thaumatin-like protein (TLP, 25 kD), were used in tissue printing to show that the AFPs are localized in the epidermis and in cells surrounding intercellular spaces in cold-acclimated plants. Although GLPs, CLPs, and TLPs were present in nonacclimated plants, they were found in different locations and did not exhibit antifreeze activity, which suggests that different isoforms of pathogenesis-related proteins are produced at low temperature. The location of rye AFPs may prevent secondary nucleation of cells by epiphytic ice or by ice propagating through the xylem. The distributions of pathogenesis-induced and cold-accumulated GLPs, CLPs, and TLPs are similar and may reflect the common pathways by which both pathogens and ice enter and propagate through plant tissues. PMID:12226223

  18. RF Front End Interface and AGC Modification

    NASA Technical Reports Server (NTRS)

    Yost, S. R.

    1982-01-01

    The latest RF front end built by Burhans (Mini-L-82) was successfully interfaced to the Ohio University LORAN-C receiver. In order for the front end to operate optimally, modifications were made to existing automatic gain control (AGC) circuitry already developed for the Ohio University LORAN-C receiver. The hardware modifications to the AGC and other interface circuitry, as well as some preliminary results are discussed.

  19. Does Your Front Desk Staff Maximize Collections?

    PubMed

    Weinstock, Donna

    2015-01-01

    As collections become more difficult, practices need to use the front desk to help collect payments from patients when they are face to face. Training staff and giving them the tools to ask for money allows them to collect efficiently. Improve your collections by involving your front desk employees. Educate your patients to allow them to come to their visits prepared. It will save the practice time and money. PMID:26399028

  20. Foliar applied abscisic acid increases 'Chardonnay' grapevines (Vitis vinifera) bud freezing tolerance during Autumn cold acclimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Economic loss due to cold weather events is a major constraint to winegrape-related industries where extreme and/or fluctuating winter temperatures induce injury and required remedial retraining and replanting increases production costs and lowers yield and fruit quality. The purpose of this study ...