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Sample records for 2510p dell latitude

  1. Dell's Different Direction.

    PubMed

    Price, Sean

    2017-05-01

    The unique curriculum at The University of Texas at Austin Dell Medical School practically does away with traditional lectures and focuses instead on solving problems and working together with other health care professionals.

  2. The power of virtual integration: an interview with Dell Computer's Michael Dell. Interview by Joan Magretta.

    PubMed

    Dell, M

    1998-01-01

    Michael Dell started his computer company in 1984 with a simple business insight. He could bypass the dealer channel through which personal computers were then being sold and sell directly to customers, building products to order. Dell's direct model eliminated the dealer's markup and the risks associated with carrying large inventories of finished goods. In this interview, Michael Dell provides a detailed description of how his company is pushing that business model one step further, toward what he calls virtual integration. Dell is using technology and information to blur the traditional boundaries in the value chain between suppliers, manufacturers, and customers. The individual pieces of Dell's strategy--customer focus, supplier partnerships, mass customization, just-in-time manufacturing--may be all be familiar. But Michael Dell's business insight into how to combine them is highly innovative. Direct relationships with customers create valuable information, which in turn allows the company to coordinate its entire value chain back through manufacturing to product design. Dell describes how his company has come to achieve this tight coordination without the "drag effect" of ownership. Dell reaps the advantages of being vertically integrated without incurring the costs, all the while achieving the focus, agility, and speed of a virtual organization. As envisioned by Michael Dell, virtual integration may well become a new organizational model for the information age.

  3. Streaking into Middle School Science: The Dell Streak Pilot Project

    ERIC Educational Resources Information Center

    Austin, Susan Eudy

    2012-01-01

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the…

  4. Streaking into Middle School Science: The Dell Streak Pilot Project

    ERIC Educational Resources Information Center

    Austin, Susan Eudy

    2012-01-01

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the…

  5. High Latitude Polygons

    NASA Technical Reports Server (NTRS)

    2005-01-01

    26 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows polygonal patterned ground on a south high-latitude plain. The outlines of the polygons, like the craters and hills in this region, are somewhat enhanced by the presence of bright frost left over from the previous winter. On Earth, polygons at high latitudes would usually be attributed to the seasonal freezing and thawing cycles of ground ice. The origin of similar polygons on Mars is less certain, but might also be an indicator of ground ice.

    Location near: 75.3oS, 113.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  6. High latitude scintillations

    NASA Astrophysics Data System (ADS)

    Basu, Santimay; Basu, Sunanda

    High-latitude phase and amplitude scintillations have been observed with quasi-geostationary polar beacon satellites, high-altitude orbiting GPS satellites, and low-altitude orbiting HiLat and Polar Bear satellites. The scintillation behavior observed in the polar cap, cusp, and nightside auroral oval is described. Consideration is given to the possible mechanisms for the generation of irregularities that cause scintillations. The importance of coordinated multitechnique measurements for scintillation studies is stressed.

  7. High Latitude Ionospheric Structures

    DTIC Science & Technology

    2006-06-01

    CADI are a mixture of ionograms and ‘fixed’ frequency. The fixed frequency is chosen so as to get continuous ionospheric echoes throughout the day...because of the very dynamic ionospheric behaviour at high latitudes. Ionograms (interleaved with the fixed frequency observations) are at less frequent...intervals, typically each minute. In general it is easier to identify structures on the fixed frequency recordings. Ionograms are mainly useful when

  8. Liven up Your Student Dramatics with Commedia dell' Arte.

    ERIC Educational Resources Information Center

    Potter, Jonathan

    1980-01-01

    Suggests using the ancient Commedia dell' Arte technique of establishing characters and a plot and then allowing the actors to create their own play. Indicates that this improves student performances even in more traditional plays. (TJ)

  9. 11. REPRESENTATIVE VIEW OF DELL AVENUE VEHICULAR BRIDGES, LOOKING WEST ...

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

    11. REPRESENTATIVE VIEW OF DELL AVENUE VEHICULAR BRIDGES, LOOKING WEST FROM SOUTH SIDE OF LINNIE CANAL. THIS PARTICULAR BRIDGE IS LOCATED OVER LINNIE CANAL. - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA

  10. Liven up Your Student Dramatics with Commedia dell' Arte.

    ERIC Educational Resources Information Center

    Potter, Jonathan

    1980-01-01

    Suggests using the ancient Commedia dell' Arte technique of establishing characters and a plot and then allowing the actors to create their own play. Indicates that this improves student performances even in more traditional plays. (TJ)

  11. Mid-latitude Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    7 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark sand dunes on the floor of a southern mid-latitude impact crater. Craters are commonly the site of sand dunes, as sand may become trapped in these topographic depressions. In this case, the winds responsible for the dunes generally blew from the south/southeast (bottom/lower right),

    Location near: 51.8oS, 105.5oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  12. Mid-latitude Gullies

    NASA Technical Reports Server (NTRS)

    2005-01-01

    25 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of south mid-latitude gullies on a crater wall. Gullies such as these may have formed by runoff of liquid water.

    Location near: 38.0oS, 167.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  13. The Sinkholes at "Piano dell'Acqua

    NASA Astrophysics Data System (ADS)

    Iovine, G. G. R.; Parise, M.; Caloiero, T.; Lanza, G.; Suriano, S.

    2012-04-01

    Five sinkholes have recently been identified in the territory of San Basile (Northern Calabria, Southern Italy), in locality "Piano dell'Acqua". The sinkholes are located in a hilly setting, where the main landform is represented by a slight valley draining toward the east. The sinkholes are limited in size, with maximum diameter of 10 m, and maximum depth of 2.5 m. Two of them are elongated, whilst the remaining three are circular. The area where the sinkholes develop is characterized by Pliocene conglomerate and sand, likely dislocated by tectonic lines. The sinkholes were initially examined by means of multi-temporal aerial photos, and the outcomes from this analysis were checked in the field through geological, structural and geomorphological surveys. At the same time, an historical analysis was started in order to collect and critically evaluate the existing information and testimonies about age of occurrence of the phenomena. At this aim, several interviews with local inhabitants were performed, and a number of archives scrutinized. As a result, the study allowed to hypothesize that two sinkholes developed during the winter 2000-2001, with likely rapid formation. Two other cases probably originated during the 70's, as also suggested by the age of the vegetation hosted within the sinkholes. The last sinkhole, eventually, opened sometime between February 2001 and November 2007. According to the collected testimonies, a further phase of sinkhole development might have occurred in the first half of the past Century, but no field evidence of this older phase has been found so far. Analysis of the seismic catalogues showed that no earthquake can be identified as possible trigger of any of the sinkholes at Piano dell'Acqua. Therefore, the origin of the studied phenomena should be related to sub-cutaneous erosion, within an area that is rich in groundwater (as also shown by the site name, meaning "Water Plain"). Local changes in the water table, both related to

  14. Solar Diameter Latitude Dependence

    NASA Astrophysics Data System (ADS)

    Emilio, M.; Leister, N. V.; Laclare, F.

    The observing programs of the Sun for determining the fundamental system of reference enable, as a by-product, to measure the apparent solar diameter (Poppe, P.C.R. et al. 1996; Leister et al. 1996; Laclare et al. 1991). The diameter obtained at the Calern Observatory (φ = 43-circ 44' 55''.9; λ = -0h 27m 42s.44) and at Abrahao de Moraes Observatory (OAM) (φ = -23-circ 00'6''.0; λ = 3h 07m 52s.22) was analyzed searching for periodicity evidences. For this we utilized the temporal methods CLEAN and CLEANEST. The analysis in function of heliographic latitude shows a dependence that may be correlated to mode of pulsation non-radial gravity. A discussion is made in terms of physical parameters like temperature luminosity and magnetic field involving the solar radius (Emilio M. 1997; Laclare et al. 1996).

  15. Ulysses breaks latitude record

    NASA Astrophysics Data System (ADS)

    1993-06-01

    Ulysses is gathering important new information concerning the Sun and its environment. Its prime mission objective is to carry out the first systematic exploration of the inner part of the heliosphere - the region of space carved out of the interstellar medium by the solar wind - at all latitudes from the solar equator to the poles. The spacecraft, launched by the space shuttle Discovery on 6 October 1990 in the framework of an ESA-NASA collaborative venture, underwent a gravity assist manoeuvre at Jupiter in February 1992 and is now in a highly inclined solar orbit that will bring it over the south pole of the Sun in September 1994. At that time, Ulysses will establish a new record as it climbs to its maximum latitude of just over 80 degrees. The spacecraft and its scientific instruments are in excellent condition and the data coverage since launch has been consistently close to 100% thanks to the dedicated efforts of the joint ESA-NASA Mission Operations Team and NASA's Deep Space Network. Although the most exciting phase of the mission - the study of the Sun's polar regions - will only begin in mid-1994, Ulysses has already produced a wealth of new scientific results. These include : * - The first direct detection of neutral helium atoms arriving from interstellar space. * - The measurement of micron-sized dust grains arriving from interstellar space. * - The first measurement of singly-charged H, N, O and Ne ions which entered the heliosphere as interstellar neutral atoms and were then ionised. * - The highest-resolution measurements to date of the isotopic composition of cosmic ray nuclei (e.g. C, N, O, Ne, Si and Mg). In addition to the above, the traversal of Jupiter's magnetosphere at the time of the fly-by enabled the Ulysses investigators to acquire new and highly valuable data concerning this very complex and dynamic plasma environment. Among the more exciting results to emerge are the possible entry into the polar cap of Jupiter's magnetosphere near the

  16. Implementing an ROI Measurement Process at Dell Computer.

    ERIC Educational Resources Information Center

    Tesoro, Ferdinand

    1998-01-01

    This return-on-investment (ROI) evaluation study determined the business impact of the sales negotiation training course to Dell Computer Corporation. A five-step ROI measurement process was used: Plan-Develop-Analyze-Communicate-Leverage. The corporate sales information database was used to compare pre- and post-training metrics for both training…

  17. Implementing an ROI Measurement Process at Dell Computer.

    ERIC Educational Resources Information Center

    Tesoro, Ferdinand

    1998-01-01

    This return-on-investment (ROI) evaluation study determined the business impact of the sales negotiation training course to Dell Computer Corporation. A five-step ROI measurement process was used: Plan-Develop-Analyze-Communicate-Leverage. The corporate sales information database was used to compare pre- and post-training metrics for both training…

  18. Playing Funny: An Introduction to "Commedia dell' Arte."

    ERIC Educational Resources Information Center

    Grantham, Barry

    2001-01-01

    Discusses the use of "Commedia," a way of performing inspired by the historical "Commedia dell' Arte." Notes that it has proved a fertile source of inspiration for all types of physical and stylized theatre and a useful training tool for performers in many fields. Presents a series of exercises designed to introduce the student to Commedia…

  19. Playing Funny: An Introduction to "Commedia dell' Arte."

    ERIC Educational Resources Information Center

    Grantham, Barry

    2001-01-01

    Discusses the use of "Commedia," a way of performing inspired by the historical "Commedia dell' Arte." Notes that it has proved a fertile source of inspiration for all types of physical and stylized theatre and a useful training tool for performers in many fields. Presents a series of exercises designed to introduce the student to Commedia…

  20. 75 FR 28657 - Dell Products LP-Parmer North Location, a Subsidiary of Dell, Inc., Including On-Site Leased...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    ...., Including On-Site Leased Workers From Belcan Services Group, Hawkins Associates, Inc., Integrated Human Capital, MagRabbit, Manpower and Spherion Corporation; Round Rock, TX; Dell Products LP--Parmer North One...., including on-site leased workers from Belcan Services Group, Hawkins Associates Inc., Integrated...

  1. Analysis of daily latitude variations

    NASA Technical Reports Server (NTRS)

    Graber, M. A.

    1979-01-01

    The daily latitude measurements of the International Polar Motion Service are analyzed. The annual oscillation in the data was modeled by separate oscillations in each observatory's latitude data. The separate oscillations varied in amplitude from 0.05 sec to 0.15 sec with standard deviations of about 0.007 sec. Within the resolution of the latitude residuals (150 cm), there is no indication of the sharp changes which might be associated with earthquake effects. Then, applying Schuster's test to a periodogram of the residuals indicates that there are probably several processes occurring at amplitudes between 0.007 sec and 0.03 sec whose solution awaits a more precise measurement technique.

  2. Latitudes: new Indian transnational cinema.

    PubMed

    Villarejo, Amy

    2014-01-01

    This article examines films and video art that speak to conditions of exile and displacement, including the work of Mona Hatoum, Sonali Gulati, and Onir. It proposes the term "latitude" to interrogate the aesthetic and formal properties of these artworks, seeking to understand how lesbian and same-sex eroticism and identities are central to their efficacy.

  3. When Poetry became Ethnography and Other Flying Pig Tales in Honor of Dell Hymes

    ERIC Educational Resources Information Center

    Cahnmann-Taylor, Melisa

    2011-01-01

    Cahnmann-Taylor remembers her first encounter with Dell Hymes at an open mic event at the annual meeting of the American Anthropological Association. She puzzles his complex stance on the role ethnographic poems might play in one's ethnographic project. In Dell Hymes's honor, she shares a poetic rendering of a speech event from her bilingual…

  4. A Literary and Linguistic Analysis of Scott O'Dell's "The Captive".

    ERIC Educational Resources Information Center

    Stewig, John Warren

    This paper carefully examines the literary elements Scott O'Dell uses in his children's novel "The Captive," that so successfully engage even a reluctant reader. The paper explores the writer's style and subtle use of detail and foreshadowing. Quoting specific examples, the paper points out O'Dell's imaginative syntax and his ability to…

  5. Enabling Customization through Web Development: An Iterative Study of the Dell Computer Corporation Website

    ERIC Educational Resources Information Center

    Liu, Chang; Mackie, Brian G.

    2008-01-01

    Throughout the last decade, companies have increased their investment in electronic commerce (EC) by developing and implementing Web-based applications on the Internet. This paper describes a class project to develop a customized computer website which is similar to Dell Computer Corporation's (Dell) website. The objective of this project is to…

  6. Enabling Customization through Web Development: An Iterative Study of the Dell Computer Corporation Website

    ERIC Educational Resources Information Center

    Liu, Chang; Mackie, Brian G.

    2008-01-01

    Throughout the last decade, companies have increased their investment in electronic commerce (EC) by developing and implementing Web-based applications on the Internet. This paper describes a class project to develop a customized computer website which is similar to Dell Computer Corporation's (Dell) website. The objective of this project is to…

  7. When Poetry became Ethnography and Other Flying Pig Tales in Honor of Dell Hymes

    ERIC Educational Resources Information Center

    Cahnmann-Taylor, Melisa

    2011-01-01

    Cahnmann-Taylor remembers her first encounter with Dell Hymes at an open mic event at the annual meeting of the American Anthropological Association. She puzzles his complex stance on the role ethnographic poems might play in one's ethnographic project. In Dell Hymes's honor, she shares a poetic rendering of a speech event from her bilingual…

  8. A Literary and Linguistic Analysis of Scott O'Dell's "The Captive".

    ERIC Educational Resources Information Center

    Stewig, John Warren

    This paper carefully examines the literary elements Scott O'Dell uses in his children's novel "The Captive," that so successfully engage even a reluctant reader. The paper explores the writer's style and subtle use of detail and foreshadowing. Quoting specific examples, the paper points out O'Dell's imaginative syntax and his ability to…

  9. Joule heating at high latitudes

    NASA Technical Reports Server (NTRS)

    Foster, J. C.; St.-Maurice, J.-P.; Abreu, V. J.

    1983-01-01

    Calculations based on simultaneous observations of the electric field magnitude, and individual measurements of ion drift velocity and particle precipitation, over the lifetime of the AE-C satellite, are used to determine high latitude Joule heating. Conductivities produced by an averaged seasonal illumination were included with those calculated from particle precipitation. It is found that high latitude Joule heating occurs in an approximately oval pattern, and consists of dayside cleft, dawn and dusk sunward convection, and night sector heating regions. On average, heating in the cleft and dawn-dusk regions contributes the largest heat input, and there is no apparent difference between hemispheres for similar seasons. Joule heat input is 50 percent greater in summer than in winter, due primarily to the greater conductivity caused by solar production.

  10. Titan's Mid-latitude Clouds

    NASA Astrophysics Data System (ADS)

    Roe, Henry G.; Schaller, E. L.; Trujillo, C. A.; Brown, M. E.

    2007-10-01

    In the first few years of spatially resolved observations of Titan's tropospheric methane clouds (2001-2003) all of the clouds were clustered in the south polar region. This time period coincided with the southern summer solstice (October 2002) and these south polar clouds are almost certainly a seasonal phenomenon. Starting in December 2003 we began seeing clouds in a narrow latitude range centered at 40°S latitude. In Roe et al. (2005a) we published this initial discovery and speculated that the clouds might be due either to changes in the seasonal circulation pattern or a process linked to surface geography. Further observations soon revealed that the clouds were significantly clustered over one region of longitude (near 350°W), strongly suggesting a geographically controlled origin (Roe et al. 2005b), although Cassini observations suggest a circulation-induced convergence origin (Griffith et al. 2005). The actual answer is most likely a combination of geographic surface effects with the atmospheric circulation. We report here on our continuing ground-based observation campaign, including observations on 65 nights in the 2006-2007 apparition with the Gemini 8-m telescope. With two more years of observations since the data shown in Roe et al. (2005b) we now have much firmer conclusions with respect to the spatial distribution and temporal characteristics of the mid-latitude clouds. We will present our latest understanding of Titan's mid-latitude clouds given the entire dataset now available to us. References Griffith, C.A., & 26 co-authors 2005. Science, 310, 474. Roe, H.G., A.H. Bouchez, C.A. Trujillo, E.L. Schaller, & M.E. Brown 2005a. ApJL, 618, 49. Roe, H.G., M.E. Brown, E.L. Schaller, A.H. Bouchez, & C.A. Trujillo 2005b. Science, 310, 477. This work is supported by NASA under Grant #NNX07AK74G issued through the Planetary Astronomy Program.

  11. 76 FR 27366 - CEVA Freight, LLC, Dell Logistics Division, Including On-Site Leased Workers From Prologistix...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-11

    ... Employment and Training Administration CEVA Freight, LLC, Dell Logistics Division, Including On-Site Leased..., LLC, Dell Logistics Division, including on-site leased workers from Prologistix, Winston-Salem, North... intent of the Department's certification is to include all workers employed at CEVA Freight, LLC, Dell...

  12. 75 FR 38128 - Ceva Freight, LLC, Dell Logistics Division, Including On-Site Leased Workers From Prologistix and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... Employment and Training Administration Ceva Freight, LLC, Dell Logistics Division, Including On-Site Leased..., LLC, Dell Logistics Division, including on-site leased workers from Prologistix, Winston-Salem, North..., Dell Logistics Division. The Department has determined that these workers were sufficiently under the...

  13. Streaking into middle school science: The Dell Streak pilot project

    NASA Astrophysics Data System (ADS)

    Austin, Susan Eudy

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the Streak could be used as an effective instructional tool, and if it could be considered an effective instructional resource for reviewing and preparing for the science assessments. A mixed method research design was used for the study to analyze both quantitative and qualitative results to determine if the Dell Streaks' utilization could achieve the following: 1. instructional strategies would change, 2. it would be an effective instructional tool, and 3. a comparison of the students' test scores and benchmark assessments' scores would provide statistically significant difference. Through the use of an ANOVA it was determined a statistically significant difference had occurred. A Post Hoc analysis was conducted to identify where the difference occurred. Finally a T-test determined was there was no statistically significance difference between the mean End-of-Grade tests and four quarterly benchmark scores of the control and the experimental groups. Qualitative research methods were used to gather results to determine if the Streaks were an effective instructional tool. Classroom observations identified that the teacher's teaching styles and new instructional strategies were implemented throughout the pilot project. Students had an opportunity to complete a questionnaire three times during the pilot project. Results revealed what the students liked about using the devices and the challenges they were facing. The teacher completed a reflective questionnaire throughout the pilot project and offered valuable reflections about the use of the devices in an educational setting. The reflection data supporting the case study was drawn

  14. Latitude, Birth Date, and Allergy

    PubMed Central

    Wjst, Matthias; Dharmage, Shyamali; André, Elisabeth; Norback, Dan; Raherison, Chantal; Villani, Simona; Manfreda, Jure; Sunyer, Jordi; Jarvis, Deborah; Burney, Peter; Svanes, Cecilie

    2005-01-01

    Background The space and time distribution of risk factors for allergic diseases may provide insights into disease mechanisms. Allergy is believed to vary by month of birth, but multinational studies taking into account latitude have not been conducted. Methods and Findings A questionnaire was distributed in 54 centres to a representative sample of 20- to 44-y-old men and women mainly in Europe but also including regions in North Africa, India, North America, Australia, and New Zealand. Data from 200,682 participants were analyzed. The median prevalence of allergic rhinitis was 22%, with a substantial variation across centres. Overall, allergic rhinitis decreased with geographical latitude, but there were many exceptions. No increase in prevalence during certain winters could be observed. Also, no altered risk by birth month was found, except borderline reduced risks in September and October. Effect estimates obtained by a multivariate analysis of total and specific IgE values in 18,085 individuals also excluded major birth month effects and confirmed the independent effect of language grouping. Conclusion Neither time point of first exposure to certain allergens nor early infections during winter months seems to be a major factor for adult allergy. Although there might be effects of climate or environmental UV exposure by latitude, influences within language groups seem to be more important, reflecting so far unknown genetic or cultural risk factors. PMID:16190778

  15. High Latitude Mottling on Jupiter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The familiar banded appearance of Jupiter at low and middle latitudes gradually gives way to a more mottled appearance at high latitudes in this striking true color image taken Dec. 13, 2000, by NASA's Cassini spacecraft.

    The intricate structures seen in the polar region are clouds of different chemical composition, height and thickness. Clouds are organized by winds, and the mottled appearance in the polar regions suggests more vortex-type motion and winds of less vigor at higher latitudes.

    The cause of this difference is not understood. One possible contributor is that the horizontal component of the Coriolis force, which arises from the planet's rotation and is responsible for curving the trajectories of ocean currents and winds on Earth, has its greatest effect at high latitudes and vanishes at the equator. This tends to create small, intense vortices at high latitudes on Jupiter. Another possibility may lie in that fact that Jupiter overall emits nearly as much of its own heat as it absorbs from the Sun, and this internal heat flux is very likely greater at the poles. This condition could lead to enhanced convection at the poles and more vortex-type structures. Further analysis of Cassini images, including analysis of sequences taken over a span of time, should help us understand the cause of equator-to-pole differences in cloud organization and evolution.

    By the time this picture was taken, Cassini had reached close enough to Jupiter to allow the spacecraft to return images with more detail than what's possible with the planetary camera on NASA's Earth-orbiting Hubble Space Telescope. The resolution here is 114 kilometers (71 miles) per pixel. This contrast-enhanced, edge-sharpened frame was composited from images take at different wavelengths with Cassini's narrow-angle camera, from a distance of 19 million kilometers (11.8 million miles). The spacecraft was in almost a direct line between the Sun and Jupiter, so the solar illumination on

  16. Relationship between Latitude and Melanoma in Italy

    PubMed Central

    Crocetti, Emanuele; Buzzoni, Carlotta; Chiarugi, Alessandra; Nardini, Paolo; Pimpinelli, Nicola

    2012-01-01

    Objective. Evaluate the ecological relationship between skin melanoma epidemiology and latitude in Italy. Methods. We used data from the Italian network of cancer registries (Airtum). In a Poisson model, we evaluated the effect on incidence, mortality, and survival of latitude, adjusting for some demographic, social, phenotypic, and behavioural variables. Results. Incidence increased in Italy by 17% for each degree of increase in latitude. The effect of latitude was statistically significantly present also adjusting for other variables (incidence rate ratio = 1.08). The effect of latitude on increasing mortality (mortality rate ratio = 1.27) and improving survival (relative excess risk of death = 0.93) was no longer present in the multivariate model. Conclusion. Melanoma incidence, mortality, and survival vary in Italy according to latitude. After adjustment for several confounders, incidence still grows with growing latitude. Presumably, latitude expresses other variables that might be related to individual susceptibility and/or local care. PMID:22389841

  17. Relationship between Latitude and Melanoma in Italy.

    PubMed

    Crocetti, Emanuele; Buzzoni, Carlotta; Chiarugi, Alessandra; Nardini, Paolo; Pimpinelli, Nicola

    2012-01-01

    Objective. Evaluate the ecological relationship between skin melanoma epidemiology and latitude in Italy. Methods. We used data from the Italian network of cancer registries (Airtum). In a Poisson model, we evaluated the effect on incidence, mortality, and survival of latitude, adjusting for some demographic, social, phenotypic, and behavioural variables. Results. Incidence increased in Italy by 17% for each degree of increase in latitude. The effect of latitude was statistically significantly present also adjusting for other variables (incidence rate ratio = 1.08). The effect of latitude on increasing mortality (mortality rate ratio = 1.27) and improving survival (relative excess risk of death = 0.93) was no longer present in the multivariate model. Conclusion. Melanoma incidence, mortality, and survival vary in Italy according to latitude. After adjustment for several confounders, incidence still grows with growing latitude. Presumably, latitude expresses other variables that might be related to individual susceptibility and/or local care.

  18. Analysis of daily latitude variations

    NASA Technical Reports Server (NTRS)

    Graber, M. A.

    1978-01-01

    The daily latitude measurements of the International polar motion service are analyzed. The results indicate that the annual polar oscillation is probably due to local phenomena with amplitudes varying from 0.05 to 0.15 min. Within the resolution of the residuals (150 cm), there is no indication of the sharp changes which might be associated with earthquake effects. Then, applying Schuster's test to a periodogram of the residuals indicates that there are probably several processes occurring at amplitudes between 0.007 and 0.03 min whose solution awaits a more precise measurement technique.

  19. Latitude and longitude vertical disparity

    PubMed Central

    Read, Jenny C. A.; Phillipson, Graeme P.; Glennerster, Andrew

    2010-01-01

    The literature on vertical disparity is complicated by the fact that several different definitions of the term “vertical disparity” are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparity. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out. We present analytical approximations for each type of vertical disparity, valid for more general conditions than previous derivations in the literature: we do not restrict ourselves to objects near the fixation point or near the plane of regard, and we allow for non-zero torsion, cyclovergence and vertical misalignments of the eyes. We use these expressions to derive estimates of the latitude and longitude vertical disparity expected at each point in the visual field, averaged over all natural viewing. Finally, we present analytical expressions showing how binocular eye position – gaze direction, convergence, torsion, cyclovergence, and vertical misalignment – can be derived from the vertical disparity field and its derivatives at the fovea. PMID:20055544

  20. South Mid-latitude Gullies

    NASA Technical Reports Server (NTRS)

    2005-01-01

    19 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows deep gullies cut into the wall of a south mid-latitude crater. Erosion has exposed layers in the upper wall of the crater; it is possible that groundwater seeping through a layer or layers in the wall led to the genesis of the gullies. The banked nature of the gully channels suggests that a liquid was involved.

    Location near: 35.5oS, 194.8oW Image width: width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Spring

  1. Surviving Rescue: A Feminist Reading of Scott O'Dell's "Island of the Blue Dolphins"

    ERIC Educational Resources Information Center

    Baecker, Diann L.

    2007-01-01

    Scott O'Dell's "Island of the Blue Dolphins" tells the archetypal story of the young, virgin, orphan girl who is vulnerable to either debauchery or rescue. That such a girl must succumb to either one or the other is a necessary element of the archetype. In O'Dell's work--one intended, after all, for children--the heroine is rescued by a…

  2. Surviving Rescue: A Feminist Reading of Scott O'Dell's "Island of the Blue Dolphins"

    ERIC Educational Resources Information Center

    Baecker, Diann L.

    2007-01-01

    Scott O'Dell's "Island of the Blue Dolphins" tells the archetypal story of the young, virgin, orphan girl who is vulnerable to either debauchery or rescue. That such a girl must succumb to either one or the other is a necessary element of the archetype. In O'Dell's work--one intended, after all, for children--the heroine is rescued by a…

  3. Low-latitude ionospheric effects on SBAS

    NASA Astrophysics Data System (ADS)

    Arenas, J.; Sardón, E.; Sainz, A.; Ochoa, B.; Magdaleno, S.

    2016-06-01

    Satellite-based augmentation systems (SBAS) provide augmentation to Global Navigation Satellite Systems (GNSS) users in three areas: (1) broadcasting accurate corrections to GNSS satellite ephemeris, (2) providing a real-time empirical ionospheric model in the service area, and (3) providing integrity information in the form of estimates of the confidence of the ephemeris corrections and ionospheric delays. Ionospheric effects on SBAS are twofold: (a) the input data used by the SBAS will be affected by ionospheric effects, and (b) the more perturbed the ionosphere is, the more difficult it will be to provide accurate and reliable ionospheric information to the users. The ionosphere at low latitudes presents larger variability and more intense phenomena than at midlatitudes. Therefore, SBAS providing service to low-latitude regions will be more affected than those at other latitudes. From the different low-latitude ionospheric effects, this paper will focus on those having the largest impact on SBAS, which are total electron content temporal and spatial gradients, ionospheric scintillations, and depletions. This paper will present the impact of these effects on EGNOS (European Global Navigation Overlay System), the European SBAS. Although EGNOS can be considered as a midlatitude SBAS, it has to provide coverage down to rather low latitudes, so sometimes low-latitude ionospheric effects are observed in the EGNOS data. It will be shown how EGNOS performs under nominal conditions and how its performance is degraded when low-latitude ionospheric phenomena occur. Real EGNOS data affected by low-latitude ionospheric phenomena will be used.

  4. Low latitude electrodynamic plasma drifts - A review

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.

    1991-01-01

    The characteristics and driving mechanisms of low latitude ExB plasma drifts and electric fields particularly at F-region heights are reviewed. It is concluded that the general characteristics of the quiet-time plasma can be explained as resulting from E- and F-region dynamo and interhemispheric coupling processes. The disturbance dynamo effects are found to be responsible for the drift perturbations following the periods of enhanced magnetic activity. The prompt penetration of high-latitude electric fields to lower latitudes produces large perturbations on the upward/poleward drifts, but has no significant effect on the low-latitude and the equatorial zonal drifts. Detailed low-latitude and global numerical models for studying the characteristics of plasma drifts are capable of reproducing the latitudinal variation of the perturbation electric fields and their diurnal variations.

  5. ``Polar'' and ``high-latitude'' substorms

    NASA Astrophysics Data System (ADS)

    Despirak, Irina; Lubchich, Andris; Kleimenova, Natalia

    All substorms observed at high latitudes can be divided into 2 types - "polar" (observed only at > 70º latitudes in the absence of substorms at <70º latitudes during the day) and "high-latitude" substorms (propagating from auroral (<70º) to polar (> 70º) geomagnetic latitudes). The aim of this study was to compare solar wind conditions during these two types of substorms. For this purpose, we used the data of IMAGE magnetometers and OMNI solar wind data for 1995, 2000, 2006-2011 periods. There were selected 105 "polar" and 55 "high-latitude" substorms. It is shown that "polar" substorms observed during the late recovery phase of a geomagnetic storm, after passing of the high speed stream of the solar wind (when the velocity is reduced from high to low values). "High-latitude" substorms, on the contrary, are observed during passing of the recurrent high-speed stream of the solar wind, increased values of the southward B _{Z }component of the IMF and E _{Y} component of the electric field, increased temperature and pressure of the solar wind. Also, it is noted that variability of these solar wind parameters for the “high-latitude” substorms is stronger than for “polar” substorms.

  6. Jupiter's Temperatures--Broad Latitude

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is one of the highest resolution images ever recorded of Jupiter's temperature field. It was obtained by NASA's Galileo mission, with its Photopolarimeter-Radiometer (PPR) experiment, during the seventh of its 10 orbits around Jupiter to date. This map, shown in the left panel, indicates the forces powering Jovian winds, and differentiates between areas of strongest upwelling and downwelling winds in the upper part of the atmosphere. A Hubble Space Telescope Planetary Camera color composite of this same region, taken within 10 hours of the PPR map, is shown in the right panel for the same region, as a reference to the visual clouds. An outline of the region mapped by the PPR is also shown.

    This atmospheric observation covered a broad latitude region, and it shows that the visually dark regions generally have warmer temperatures than the visually light ones, indicating that they are regions of downwelling, dry air which clear out cloud condensate particles. The 'little red spot' at the northernmost part of this image is colder than its surroundings, consistent with it being a region of upwelling and cooling gas. The smaller spots to its southeast (lower right) and other lighter spots in the HST image are all colder than their surroundings, consistent with regions of upwelling and cooling gas. The northern half of the brightest band in the map is brighter than the southern half, and it reveals some detailed structure, down to the 1900- kilometer (1200-mile) resolution of the PPR, which is not always readily correlated with variations of the visual cloud field.

    One surprise of this temperature map involved temperatures near the dark blue-gray feature in the map, an area like the one into which the Probe descended. While large regions of downwelling wind heat the local area elsewhere in Jupiter, this region of vigorous downwelling appears close to being thermally neutral. The drying, downwelling winds may be deeper in the atmosphere than sensed by the PPR

  7. Jupiter's Temperatures--Broad Latitude

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This is one of the highest resolution images ever recorded of Jupiter's temperature field. It was obtained by NASA's Galileo mission, with its Photopolarimeter-Radiometer (PPR) experiment, during the seventh of its 10 orbits around Jupiter to date. This map, shown in the left panel, indicates the forces powering Jovian winds, and differentiates between areas of strongest upwelling and downwelling winds in the upper part of the atmosphere. A Hubble Space Telescope Planetary Camera color composite of this same region, taken within 10 hours of the PPR map, is shown in the right panel for the same region, as a reference to the visual clouds. An outline of the region mapped by the PPR is also shown.

    This atmospheric observation covered a broad latitude region, and it shows that the visually dark regions generally have warmer temperatures than the visually light ones, indicating that they are regions of downwelling, dry air which clear out cloud condensate particles. The 'little red spot' at the northernmost part of this image is colder than its surroundings, consistent with it being a region of upwelling and cooling gas. The smaller spots to its southeast (lower right) and other lighter spots in the HST image are all colder than their surroundings, consistent with regions of upwelling and cooling gas. The northern half of the brightest band in the map is brighter than the southern half, and it reveals some detailed structure, down to the 1900- kilometer (1200-mile) resolution of the PPR, which is not always readily correlated with variations of the visual cloud field.

    One surprise of this temperature map involved temperatures near the dark blue-gray feature in the map, an area like the one into which the Probe descended. While large regions of downwelling wind heat the local area elsewhere in Jupiter, this region of vigorous downwelling appears close to being thermally neutral. The drying, downwelling winds may be deeper in the atmosphere than sensed by the PPR

  8. Warming: mechanism and latitude dependence

    NASA Astrophysics Data System (ADS)

    Barkin, Yury

    2010-05-01

    flows distribution with respect the Earth's hemispheres in first caused by eccentric position of the Earth core with respect to the mantle (displaced in present geological epoch in direction to Brasil). Of course the asymmetric distribution of heat loss is a long-term phenomenon in the geological history. But in present epoch due to drift of the core to the North we must observe some increasing of the heat flow of the Northern hemisphere and decreasing of the heat flow of the Southern hemisphere. In reality mentioned changes of heat flows are contrast (asymmetrical) and can have general tendency of increasing heat flows in both hemispheres (due to activization of relative oscillations of the core and mantle relatively polar axis). Contrast secular warming of Northern and Southern hemispheres of the Earth in present epoch. Dependence of warming from latitude. And warm flows are asymmetrically, more intensively warm is redistributed in northern hemisphere of the Earth and less intensively in a southern hemisphere. From here it follows, that the phenomenon of more intensive warming up of northern hemisphere, rather than southern in present period should be observed. Data of climatic observations (in first temperature trends for various latitude belts). More detailed analysis shows, that the phenomenon of warming in different form is shown in various latitudinal belts of the Earth. This phenomenon is more clearly shown in latitudinal belts further situated on latitude from South Pole, i.e. in high northern latitudes. Really, the trend of increase of temperature in northern hemisphere is characterized by greater rate, than a trend of temperature in a southern hemisphere. And not only trend components of temperatures increase with increasing of latitudes from southern pole to northern pole, but also amplitudes of decade fluctuations of temperature in high northern breadthes are more bigger than in southern hemisphere. Thus again it is necessary to expect a contrast and

  9. Electrodynamics of the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, Richard A.

    1989-01-01

    The discovery of apparent large (V/m) electric fields within the mesosphere suggests that this region is more active electrically than originally suspected. High-latitude observations have been particularly productive in developing new concepts regarding mesospheric electrodynamics. Several high-latitude observations of large mesospheric fields have been made under both quiet and aurorally active conditions but always below heights where enhanced ionizing radiations could significantly penetrate. Two measurements from Andoya, Norway, have also produced an anticorrelation of horizontal electric field directions with neutral wind velocities, leading to the theoretical description of a newly defined mechanism for V/m electric field generation involving wind-induced separation of charged aerosols. Evidence for mesospheric aerosols and winds exists at all latitudes but is most evident at high latitudes during the appearance of noctilucent and/or polar mesospheric clouds.

  10. Apianus' latitude volvelles - how were they made?

    NASA Astrophysics Data System (ADS)

    Gislén, Lars

    2017-04-01

    This paper studies the working and construction of the volvelles in Petrus Apianus' Astronomicum Caesareum that describe the latitudes of the planets. It is found that they can be constructed using a graphical method.

  11. Latitude and depth variation of solar rotation

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Harvey, J. W.; Pomerantz, M. A.

    1986-01-01

    New measurements of frequencies of various modes of acoustic waves trapped within the sun are reported for degrees up to 98 which allow the convective envelope to be isolated. For degrees between 20 anad 98, no evidence is found that internal rotation differs significantly with depth or latitude from the rotation of surface magnetic field patterns. Modes covering a wide latitude range have systematically lower frequencies than those confined near the equator, indicating the existence of a structural asymmetry within the sun.

  12. Low Latitude Aurora: Index of Solar Activity

    NASA Astrophysics Data System (ADS)

    Bekli, M. R.; Aissani, D.; Chadou, I.

    2010-10-01

    Observations of aurora borealis at low latitudes are rare, and are clearly associated with high solar activity. In this paper, we analyze some details of the solar activity during the years 1769-1792. Moreover, we describe in detail three low latitude auroras. The first event was reported by ash-Shalati and observed in North Africa (1770 AD). The second and third events were reported by l'Abbé Mann and observed in Europe (1770 and 1777 AD).

  13. Latitude character and evolution of Gnevyshev gap

    NASA Astrophysics Data System (ADS)

    Pandey, K. K.; Hiremath, K. M.; Yellaiah, G.

    2017-06-01

    The time interval, between two highest peaks of the sunspot maximum, during which activity energy substantially absorbed is called Gnevyshev gap. In this study we focus on mysterious evolution of the Gnevyshev gap by analyzing and comparing the integrated (over the whole Sun) characteristics of magnetic field strength of sunspot groups, soft x-ray flares, filaments or prominences and polar faculae. The time latitude distribution of these solar activities from photosphere to coronal height, for the low (≤50°) and high (≥50°) latitudes, shows the way Gnevyshev gap is evolved. The presence of double peak structure is noticed in high latitude (≥50°) activity. During activity maximum the depression (or valley) appearing, in different activity processes, probably due to shifting, spreading, and transfer of energy from higher to lower latitudes with the progress of solar cycle. The morphology of successive lower latitude zones, considering it as a wave pulse, appears to be modified/scattered, by certain degree due to shifting of magnetic energy to empower higher or lower latitudes.

  14. Tracer exchange between tropics and middle latitudes

    NASA Technical Reports Server (NTRS)

    Rood, Richard; Douglass, Anne; Weaver, Clark

    1992-01-01

    The interaction between the tropics and middle latitudes is studied using a tracer emitted at 50 hPa along a great circle route between Los Angeles, USA and Sydney, Australia. Though designed to examine the impact of stratospheric aircraft, the study more generally addresses the transport between tropics and middle latitudes for a three month period from January through March 1989. The results show that air is transported from the tropics to middle latitudes by planetary scale and tropospheric cyclonic scale waves. Except for intrusions by these wave events, the tropics are substantially isolated throughout the lower stratosphere. These waves draw material out of the tropics which ends up in the middle latitude westerly jets, with little material entering the winter polar latitudes prior to the springtime transition. The summer Southern Hemisphere is characterized by tracer being drawn out in streamers that extend from north and west to south and east. The material in the tropics is zonally asymmetric. The material that reaches the troposphere comes down in the synoptic scale eddies and is concentrated in the middle latitude jet stream. These characteristics are similar to those observed during the dispersion of volcanic clouds.

  15. An Unintentional System of Gaps: A Phenomenological Reading of Scott O'Dell's "Island of the Blue Dolphins."

    ERIC Educational Resources Information Center

    Tarr, C. Anita

    1997-01-01

    Argues that, in "Island of the Blue Dolphins," Scott O'Dell offers a skeleton main character (Karana). Contends that O'Dell has sketched Karana as a stereotype and that readers complete her characterization, filling out the skeleton by perpetuating the stereotypes. Points out this trading of stereotype for true character development in…

  16. An Unintentional System of Gaps: A Phenomenological Reading of Scott O'Dell's "Island of the Blue Dolphins."

    ERIC Educational Resources Information Center

    Tarr, C. Anita

    1997-01-01

    Argues that, in "Island of the Blue Dolphins," Scott O'Dell offers a skeleton main character (Karana). Contends that O'Dell has sketched Karana as a stereotype and that readers complete her characterization, filling out the skeleton by perpetuating the stereotypes. Points out this trading of stereotype for true character development in…

  17. High Latitude Dust in the Earth System

    NASA Technical Reports Server (NTRS)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; McKenna-Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (> or = 50degN and > or = 40degS) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 sq km and contribute at least 80-100 Tg/yr1 of dust to the Earth system (approx. 5% of the global dust budget); both are projected to increase under future climate change scenarios.

  18. High Latitude Dust in the Earth System

    NASA Technical Reports Server (NTRS)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; hide

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (> or = 50degN and > or = 40degS) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 sq km and contribute at least 80-100 Tg/yr1 of dust to the Earth system (approx. 5% of the global dust budget); both are projected to increase under future climate change scenarios.

  19. Polarization of competition increases with latitude.

    PubMed Central

    Barnes, David K A

    2002-01-01

    Many organisms overlap in their use of resources in space and time. Where and when resources are restricted, species must compete for them. Living space, often a critical resource controlling food and mate availability, is directly contested by organisms in most habitats. The ensuing animal interactions generally result in a winner gaining space and a loser, which may die. Contact matrices from studies of interference competition in encrusting marine Bryozoa (clonal and colonial animals), spanning at least 60 degrees latitude in both hemispheres, were analysed and subjected to a modern transitivity index. Only data for Bryozoa were used because (i) use of a single taxon with restricted ecology simplifies the scope for types of encounters, (and therefore) interpretation; and (ii) ecological bias is reduced because bryozoans are abundant at all latitudes. The analysis shows that assemblage competition is more hierarchical towards both poles. Thus, poorer competitors fail more frequently in interactions with increasing latitude. The cause of this trend is the simplification of overall outcomes between competitors, such as fewer ties, reversals in outcome or competitive loops (where low-ranking competitors beat those of higher ranking). The implication of such a trend is that the maintenance of biological diversity at high latitudes may principally be by physical rather than biological (competition) processes. Certainly, ocean surface energy increases with latitude through wind and wave action (and ice scour in polar regions). PMID:12396506

  20. Interplanetary causes of middle latitude ionospheric disturbances

    NASA Astrophysics Data System (ADS)

    Tsurutani, Bruce T.; Echer, Ezequiel; Guarnieri, Fernando L.; Verkhoglyadova, Olga P.

    The solar and interplanetary causes of major middle latitude ionospheric disturbances are reviewed. Solar flare photons can cause abrupt (within ˜5 min), 30% increases in ionospheric total electron content, a feature that can last for tens of minutes to hours, depending on the altitude of concern. Fast interplanetary coronal mass ejection sheath fields and magnetic clouds can cause intense magnetic storms if the field in either region is intensely southward for several hours or more. If the field conditions in both regions are southward, "double storms" will occur. Multiple interplanetary fast forward shocks "pump up" the sheath magnetic field, leading to conditions that can lead to superstorms. Magnetic storm auroral precipitation and Joule heating cause pressure waves that propagate from subauroral latitudes to middle and equatorial latitudes. Shocks can create middle latitude dayside auroras as well as trigger nightside subauroral supersubstorms. Solar wind ram pressure increases after fast shocks can lead to the formation of new radiation belts under proper conditions. Prompt penetration electric fields can cause a dayside ionospheric superfountain, leading to plasma transport from the equatorial region to middle latitudes. The large amplitude Alfvén waves present in solar wind high-speed streams cause sporadic magnetic reconnection, plasma injections, and electromagnetic chorus wave generation. Energetic electrons interacting with chorus (and PC5) waves are accelerated to hundreds of keV up to MeV energies.

  1. A mid-latitude scintillation model

    NASA Astrophysics Data System (ADS)

    Robins, Robert E.; Secan, James A.; Fremouw, E. J.

    1986-10-01

    Radiowave scintillation in the presence of ionospheric disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report describes development of a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed mid latitude F layer. The model will be incorporated into Program WBMOD, which includes subroutines for computing both link geometry and scintillation indices, the latter by means of phase screen diffraction theory. Earlier versions of WBMOD, were based on extensive analysis of scintillation data collected in the auroral and equatorial zones in Wideband Satellite Mission. The model described herein is based on similarly extensive analysis of Wideband data from one mid latitude station and of data collected from HiLat satellite at another mid latitude station. The model describes irregularities at an effective height of 350 km that are isotropic across the geomagnetic field and elongated by a factor of 10 along the field and whose one-dimensional spatial power spectrum obeys a single regime power law with a (negative) spectral index of 1.5. The height-integrated spectral strength of the irregularities is modeled as a function apex latitude of the point. The report highlights a disagreement by a factor of approximately three between irregularity strength inferred from the two satellites in a region of overlap between the two mid-latitude stations.

  2. Magnetic field rotation at high solar latitudes

    NASA Technical Reports Server (NTRS)

    Howard, R.

    1978-01-01

    Measurements of the rotation rate of polar magnetic features during 1974-76 lead to a significantly slower rotation rate than that found earlier for polar faculae in 1951-54. Similarly, the rotation rate of these features is slower than the Doppler-determined rate at polar latitudes or the rotation rate of polar filaments. It is suggested that the strong latitude rotation gradient in the subsurface magnetic flux tubes which is implied by these results may presage a very active solar maximum for cycle 21.

  3. Dell H. Hymes: His Scholarship and Legacy in Anthropology and Education

    ERIC Educational Resources Information Center

    Hornberger, Nancy H., Ed.

    2011-01-01

    Dell Hathaway Hymes, linguistic anthropologist and educational visionary extraordinaire, passed away in November 2009, leaving behind a voluminous scholarship and inspirational legacy in the study of language and inequality, ethnography, sociolinguistics, Native American ethnopoetics, and education. This essay provides a brief account of Hymes's…

  4. Reflections--Dell C. Kjer: A Pioneer Teacher Educator and Association Leader.

    ERIC Educational Resources Information Center

    Gilstrap, Robert L.

    2000-01-01

    Reflects upon the role of Dell C. Kjer, a leader in teacher education and president of the Association for Childhood Education International (ACEI) from 1965-1967. Describes his early years in Wisconsin, military duties and student life at George Peabody, his contributions to teacher education, and his contributions to ACEI and other professional…

  5. Dell Hymes and the New Language Policy Studies: Update from an Underdeveloped Country

    ERIC Educational Resources Information Center

    McCarty, Teresa L.; Collins, James; Hopson, Rodney K.

    2011-01-01

    This essay updates Dell Hymes's "Report from an Underdeveloped Country" (the USA), positioning our analysis in the New Language Policy Studies. Taking up Hymes's call for comparative, critical studies of language use, we examine three cases, organizing our analysis around Hymes's questions: What "counts" as a language, a language problem, and…

  6. Dell H. Hymes: His Scholarship and Legacy in Anthropology and Education

    ERIC Educational Resources Information Center

    Hornberger, Nancy H., Ed.

    2011-01-01

    Dell Hathaway Hymes, linguistic anthropologist and educational visionary extraordinaire, passed away in November 2009, leaving behind a voluminous scholarship and inspirational legacy in the study of language and inequality, ethnography, sociolinguistics, Native American ethnopoetics, and education. This essay provides a brief account of Hymes's…

  7. Reflections--Dell C. Kjer: A Pioneer Teacher Educator and Association Leader.

    ERIC Educational Resources Information Center

    Gilstrap, Robert L.

    2000-01-01

    Reflects upon the role of Dell C. Kjer, a leader in teacher education and president of the Association for Childhood Education International (ACEI) from 1965-1967. Describes his early years in Wisconsin, military duties and student life at George Peabody, his contributions to teacher education, and his contributions to ACEI and other professional…

  8. Dell Hymes and the New Language Policy Studies: Update from an Underdeveloped Country

    ERIC Educational Resources Information Center

    McCarty, Teresa L.; Collins, James; Hopson, Rodney K.

    2011-01-01

    This essay updates Dell Hymes's "Report from an Underdeveloped Country" (the USA), positioning our analysis in the New Language Policy Studies. Taking up Hymes's call for comparative, critical studies of language use, we examine three cases, organizing our analysis around Hymes's questions: What "counts" as a language, a language problem, and…

  9. Investigating the Relationship between Latitude and Temperature

    ERIC Educational Resources Information Center

    McGivney-Burelle, Jean; McGivney, Raymond J.; McGivney, Katherine G.

    2008-01-01

    This article describes an engaging, data-gathering activity that allows students to explore relationships between latitude and average monthly temperatures of cities in the Western Hemisphere. This data-gathering activity covered interesting and important mathematical ground and engaged students from the start. While students searched for their…

  10. Higher Education in the High Latitudes.

    ERIC Educational Resources Information Center

    Bollag, Burton

    2002-01-01

    Describes how colleges in 16 countries have joined in a network to serve the educational and research needs of the circumpolar region; the University of the Arctic is a band of high-latitude colleges which seeks to serve indigenous people and preserve a fragile environment. (EV)

  11. Higher Education in the High Latitudes.

    ERIC Educational Resources Information Center

    Bollag, Burton

    2002-01-01

    Describes how colleges in 16 countries have joined in a network to serve the educational and research needs of the circumpolar region; the University of the Arctic is a band of high-latitude colleges which seeks to serve indigenous people and preserve a fragile environment. (EV)

  12. Investigating the Relationship between Latitude and Temperature

    ERIC Educational Resources Information Center

    McGivney-Burelle, Jean; McGivney, Raymond J.; McGivney, Katherine G.

    2008-01-01

    This article describes an engaging, data-gathering activity that allows students to explore relationships between latitude and average monthly temperatures of cities in the Western Hemisphere. This data-gathering activity covered interesting and important mathematical ground and engaged students from the start. While students searched for their…

  13. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    SciTech Connect

    Peek, J. E. G.; Schiminovich, David

    2013-07-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  14. Preferred latitudes of the intertropical convergence zone

    NASA Technical Reports Server (NTRS)

    Waliser, Duane E.; Somerville, C. J.

    1994-01-01

    The latitude preference of the intertropical convergence zone (ITCZ) is examined on the basis of observations, theory, and a modeling analysis. Observations show that convection is enhanced at latitudes of about 4 deg to 10 deg relative to the equator, even in regions where the sea surface temperature (SST) is maximum on the equator. Both linear shallow-water theory and a moist primitive equation model suggest a new explanation for the off-equatorial latitude preference of the ITCZ that requires neither the existence of zonally propagating disturbances nor an off-equatorial maximum in SST. The shallow-water theory indicates that a finite-width, zonally oriented, midtropospheric heat source (i.e., an ITCZ) produces the greatest local low-level convergence when placed a finite distance away from the equator. This result suggests that an ITCZ is most likely to be supported via low-level convergence of moist energy when located at these "preferred" latitudes away from the equator. For a plausible range of heating widths and damping parameters, the theoretically predicted latitude is approximately equal to the observed position (s) of the ITCZ (s). Analysis with an axially symmetric, moist, primitive equation model indicates that when the latent heating field is allowed to be determined internally, a positive feedback develops between the midtropospheric latent heating and the low-level convergence, with the effect of enhancing the organization of convection at latitudes of about 4 deg to 12 deg. Numerical experiments show that (1) two peaks in convective precipitation develop straddling the equator when the SST maximum is located on the equator; (2) steady ITCZ-like structures form only when the SST maximum is located away from the equator; and (3) peaks in convection can develop away from the maximum in SST, with a particular preference for latitudes of about 4 deg to 12 deg, even in the ('cold') hemisphere without the SST maximum. The relationship between this

  15. Penetrating of high-latitude-electric-field effects to low latitudes during SUNDIAL 1984

    NASA Technical Reports Server (NTRS)

    Spiro, R. W.; Wolf, R. A.; Fejer, B. G.

    1988-01-01

    Electric-field-penetration events have been identified using F-region vertical-drift measurements obtained in the October 6-13, 1984 period by the Jicamarcan incoherent-backscatter radar and corresponding h-prime F measurements from ionosondes at Fortaleza, Cachoeira Paulista, and Dakar. Predictions made using the Rice Convection Model for the pattern, strength, and duration of the low-latitude electric field occurring in response to an increasing high-latitude convection agree with observations. The observed 1-2 h duration of the low-latitude response to decreased convection can be explained by the fossil-wind theory of Richmond (1983).

  16. Latitude for the Observer of Ptolemy's Catalog

    NASA Astrophysics Data System (ADS)

    Schaefer, B. E.

    1999-12-01

    For centuries, researchers have claimed that substantial portions of Ptolemy's Almagest have been taken from Hipparchus in Rhodes (latitude 36.2 north). A substantial portion of these claims rest on the catalog of 1028 stars purported to be observed by Ptolemy in Alexandria (latitude 31.2 north). Various peculiarities is the star positions are inconclusive. However, aspects of the star catalog related to the visibility of stars near the horizon have not been treated with modern techniques. I have extensive experience in the heliacal rise, extinction angle, and the probability of detection (see Schaefer 1993, Vistas in Astronomy, 36, 311 for a review) all of which are critical to the problem. Also, I have been producing my own modern naked-eye star catalog so as to obtain practical knowledge of star visibility (especially near the southern horizon), completeness, and probability of detection. Also, I have determined the seasonal extinction coefficients (both median and best possible) for the eastern Mediterranean in ancient times based on 4000 in situ observations from 9 sites in modern and premodern times, measures of modern pollution components, and global models. Three criteria have been used to determine the latitude of the observer of the star catalog: First, the limiting magnitude (at the 50% level) as a function of declination can be compared against my model to derive the latitude. Second, the most southerly declination (at the 50% level) as a function of magnitude can also be compared against my model. For the first two criteria, quadrants are considered independently as well as individually to account for varying seasonal extinction and precession effects on the completeness of the traditional southern constellations. Third, the cataloged magnitudes are compared with modern magnitudes as a function of declination and compared with my extinction model for various latitudes.

  17. Wind induced composition effects at high latitudes

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Harris, I.

    1981-01-01

    The temperature and compositional structure of the upper atmosphere are discussed in relation to the impacts of wind-induced diffusion processes. Seasonal variations in thermospheric temperature and composition are explained by energy and mass transport from the summer to the winter hemisphere induced by preferential heating, with the winter oxygen bulge participating in a feedback mechanism which acts to dampen wind velocities and increase temperature contrast. Changes in the eddy diffusion coefficient are considered as a complementary mechanism of producing the seasonal anomalies. The role of winds induced by high-latitude heating by particles and Joule dissipation during magnetic storms and substorms in accounting for thermospheric density increases and N2 and Ar enhancements and O and He depletions at high latitudes are discussed, and the rather weak compositional signature of E x B momentum coupling is distinguished from the effects of Joule dissipation.

  18. Low Latitude Ionospheric Effects on Radiowave Propagation

    DTIC Science & Technology

    1998-06-01

    the cosine of the latitude, i.e., y = (lonl - lon2) * cos(Zatl) (65) and that x is the difference of the two latitudes, x = lat2 - latl. (66...25 \\-Am "li^-rrt #*! i W*9$A , i^ä—iiäBä mm. M& Ägjggj^B** y ^s: ■1.ff tf*f? ^3g?Wf«W^!f? »«jMfcwiifi i IWTI .^. ..j .-;~u.,Ix -ä^’ i_...plotting it against the data should yield a straight line at 45 °. In Figure 30 the filtered onset time is plotted on the y axis and OT from Equation 37

  19. Mid-latitude hiss and plasmaspheric notch

    NASA Astrophysics Data System (ADS)

    Masson, A.; Inan, U.; Laakso, H.; Décréau, P.; Santolik, O.

    2004-12-01

    A newly identified whistler mode ELF/VLF emission, observed by the Cluster satellites, will be presented. In the vicinity of the plasmapause, around the geomagnetic equator, the four Cluster satellites often observe banded hiss-like electromagnetic emissions (BHE). Their frequency bandwidth is always in between the lower hybrid resonance and the electron gyrofrequency, from 2 kHz to 10 kHz. Based on two years of data measured by three waves experiments on Cluster (WHISPER, STAFF and WBD), the following properties of the BHE waves have been deduced: (i) their location is strongly correlated with the position of the plasmapause, (ii) no MLT dependence has been found, (iii) their spectral width is generally 1 to 2 kHz, and (iv) the central frequency of their emission band varies from 2 kHz to 10 kHz. All these features suggest that BHE are in fact mid-latitude hiss emissions (MLH). MLH have been rarely observed on a regular basis at such altitude. Based on this survey, the central frequency of mid-latitude hiss is shown to be correlated with the Kp index. This suggests either that these banded emissions are generated in a given f/fce range, or that there is a Kp dependent Doppler shift between the satellites and a possible moving source of the MLH Mid-latitude hiss case events observed within density depletion known as plasmaspheric notch (observed by the EUV instrument on IMAGE) will be presented. A recent study showed that plasmaspheric notch plays a crucial role in the generation of higher frequency emissions such as kilometric continuum. The role of plasmaspheric notch in the generation and/or the amplification of mid-latitude hiss will be addressed.

  20. Spacecraft design project: High latitude communications satellite

    NASA Technical Reports Server (NTRS)

    Josefson, Carl; Myers, Jack; Cloutier, Mike; Paluszek, Steve; Michael, Gerry; Hunter, Dan; Sakoda, Dan; Walters, Wes; Johnson, Dennis; Bauer, Terry

    1989-01-01

    The spacecraft design project was part of AE-4871, Advanced Spacecraft Design. The project was intended to provide experience in the design of all major components of a satellite. Each member of the class was given primary responsibility for a subsystem or design support function. Support was requested from the Naval Research Laboratory to augment the Naval Postgraduate School faculty. Analysis and design of each subsystem was done to the extent possible within the constraints of an eleven week quarter and the design facilities (hardware and software) available. The project team chose to evaluate the design of a high latitude communications satellite as representative of the design issues and tradeoffs necessary for a wide range of satellites. The High-Latitude Communications Satellite (HILACS) will provide a continuous UHF communications link between stations located north of the region covered by geosynchronous communications satellites, i.e., the area above approximately 60 N latitude. HILACS will also provide a communications link to stations below 60 N via a relay Net Control Station (NCS), which is located with access to both the HILACS and geosynchronous communications satellites. The communications payload will operate only for that portion of the orbit necessary to provide specified coverage.

  1. Recurrent pulsations in Saturn's high latitude magnetosphere

    NASA Astrophysics Data System (ADS)

    Mitchell, D. G.; Carbary, J. F.; Bunce, E. J.; Radioti, A.; Badman, S. V.; Pryor, W. R.; Hospodarsky, G. B.; Kurth, W. S.

    2016-01-01

    Over the course of about 6 h on Day 129, 2008, the UV imaging spectrograph (UVIS) on the Cassini spacecraft observed a repeated intensification and broadening of the high latitude auroral oval into the polar cap. This feature repeated at least 5 times with about a 1 h period, as it rotated in the direction of corotation, somewhat below the planetary rotation rate, such that it moved from noon to post-dusk, and from roughly 77° to 82° northern latitudes during the observing interval. The recurring UV observation was accompanied by pronounced ∼1 h pulsations in auroral hiss power, magnetic perturbations consistent with small-scale field aligned currents, and energetic ion conics and electrons beaming upward parallel to the local magnetic field at the spacecraft location. The magnetic field and particle events are in phase with the auroral hiss pulsation. This event, taken in the context of the more thoroughly documented auroral hiss and particle signatures (seen on many high latitude Cassini orbits), sheds light on the possible driving mechanisms, the most likely of which are magnetopause reconnection and/or Kelvin Helmholtz waves.

  2. Environmental harshness, latitude and incipient speciation.

    PubMed

    Weir, Jason T

    2014-02-01

    Are rates of evolution and speciation fastest where diversity is greatest - the tropics? A commonly accepted theory links the latitudinal diversity gradient to a speciation pump model whereby the tropics produce species at a faster rate than extra-tropical regions. In this issue of Molecular Ecology, Botero et al. () test the speciation pump model using subspecies richness patterns for more than 9000 species of birds and mammals as a proxy for incipient speciation opportunity. Rather than using latitudinal centroids, the authors investigate the role of various environmental correlates of latitude as drivers of subspecies richness. Their key finding points to environmental harshness as a positive predictor of subspecies richness. The authors link high subspecies richness in environmental harsh areas to increased opportunities for geographic range fragmentation and/or faster rates of trait evolution as drivers of incipient speciation. Because environmental harshness generally increases with latitude, these results suggest that opportunity for incipient speciation is lowest where species richness is highest. The authors interpret this finding as incompatible with the view of the tropics as a cradle of diversity. Their results are consistent with a growing body of evidence that reproductive isolation and speciation occur fastest at high latitudes.

  3. Dune Transition in the High Southern Latitudes

    NASA Image and Video Library

    2017-04-19

    Sand dune populations on Mars can vary widely with respect to morphology, relief, and activity. One of the most striking examples occurs with the many dune fields of the high Southern latitudes. When we venture south of -60 degrees latitude, we see increasing signs of dune degradation, with subdued dune brinks and broad sandy aprons, rather than sharp, dune crests and distinct boundaries. Dunes this far south are also very modest in height, often consisting solely of flat sand sheets. Additionally, global monitoring campaigns are revealing a noticeable lack of changes in these bedform positions, whereas many dunes and ripples to the north are migrating across the surface. This image shows a moderate sized dune field (-72 degrees latitude) that displays most of these morphologic features and a noticeable absence of dune crests. This transition is likely related to polar processes, ground ice, and changes in regional climate relative to the rest of the planet. https://photojournal.jpl.nasa.gov/catalog/PIA21595

  4. Seismic refraction studies at the Painter Street bridge site, Rio Dell, California

    SciTech Connect

    Heuze, F.E.; Swift, R.P.

    1991-09-01

    This report summarizes the results of seismic refraction P- and S-wave measurements, at the site of the Painter Street bridge, in Rio Dell, California. The bridge is spanning highway US 101, 4 miles south of Fortuna, in northwestern California. This study was performed to provide an estimate of material properties for the foundation of the bridge, in support of a seismic stability analysis of the bridge performed at LLNL by D. McCallen. The Rio Dell region is seismically active and the Painter Street bridge is one of only 2 bridges of its type in California, instrumented for strong motion recordings. Measurements were made using a 12-channel Geometric/Nimbus ES 1210 Signal Enhancement Seismograph. 3 refs., 21 figs., 1 tab.

  5. Comparison of high-latitude and mid-latitude ionospheric electric fields

    NASA Technical Reports Server (NTRS)

    Carpenter, L. A.; Kirchhoff, V. W. J. H.

    1975-01-01

    Simultaneous measurements of the F region electric field by the incoherent scatter technique have been made at Chatanika, Alaska (65.1 deg N, 147.5 deg W), and Millstone Hill, Massachusetts (42.6 deg N, 71.5 deg W), on July 18-19 and Aug. 7-8, 1973. Good correlation was observed in the time variation of the perpendicular electric field at the two stations. Magnetic conditions for these days were relatively quiet with some variations evident from the high-latitude magnetograms and the Chatanika radar, but no distinct effect appeared on the mid-latitude magnetograms. Since magnetospheric electric fields are thought to be the source of high-latitude electric fields such as those observed at Chatanika, the good correlation in the perpendicular electric field for the two stations indicates that the magnetospheric originated electric fields have an appreciable effect down to at least L equals 3.2.

  6. Mid-Latitude Sedimentary Rock: Spallanzani Crater

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site]

    Although most of the best examples of layered sedimentary rock seen on Mars are found at equatorial and sub-tropical latitudes, a few locations seen at mid- and high-latitudes suggest that layered rocks are probably more common than we can actually see from orbit. One extremely good example of these 'atypical' layered rock exposures is found in the 72 km-diameter (45 miles) crater, Spallanzani (58.4oS, 273.5oW). Located southeast of Hellas Planitia, the crater is named for the 18th Century Italian biologist, Lazzaro Spallanzani (1729-1799). Picture A presents a composite of the best Viking orbiter image (VO2-504B55) of the region with 4 pictures obtained June 1999 through January 2001 by the Mars Global Surveyor Mars Orbiter Camera (MOC). Each MOC narrow angle image is 3 km across. Taken in the MOC's 'survey mode,' all four images were acquired at roughly 12 meters (39 ft) per pixel. Picture B zooms-in on the portion of the composite image that includes the 4 MOC images (the 100%-size view is 20 m (66 ft) per pixel). Other craters in the region near Spallanzani show features--at Viking Orbiter scale--that are reminiscent of the layering seen in Spallanzani. Exactly what these layers are made of and how they came to be where we see them today are mysteries, but it is possible that they are similar to the materials seen in the many craters and chasms of the equatorial latitudes on Mars.

  7. Effect of Latitude on Vitamin D Levels.

    PubMed

    Leary, Patrick F; Zamfirova, Ina; Au, Johnathan; McCracken, Ward H

    2017-07-01

    Vitamin D levels have been linked to bone health and to numerous diseases; however, an element that lacks substantial direct data and limits the evidence basis regarding whom to screen for vitamin D deficiency is the effect of latitude on vitamin D levels. To determine whether latitude influences vitamin D levels and to investigate the influence of other factors that may affect vitamin D levels, including sex, race, skin type, and body mass index. Osteopathic medical students were recruited from campuses in Bradenton, Florida, and Erie, Pennsylvania. Surveys were administered to obtain demographic information, and blood samples were drawn to measure total vitamin D levels. Two-sample t tests, Fisher exact test, and logistic regression was used to assess differences in total vitamin D levels between the 2 locations. A total of 359 medical students (aged 22-57 years) were included in the study, 194 at the Bradenton campus and 214 at the Erie campus. The mean (SD) vitamin D level was 34.5 (11.8) ng/mL among participants in Bradenton and 28.1 (12.4) ng/mL among participants in Erie. Logistic regression models revealed an adjusted OR of 3.3 (95% CI, 1.73-6.4) for deficient total vitamin D among Erie students. Non-white race, male sex, and high body mass index were also statistically significant risk factors for vitamin D deficiency in regression models (P<.05). Latitude was found to be a statistically significant risk factor for vitamin D deficiency. Additionally, the findings suggest that persons with darker skin tone and, to a lesser degree, men and persons who are overweight or obese are also at increased risk for vitamin D deficiency. Physicians should be cognizant of these risk factors when deciding whom to screen.

  8. Mid-Latitude Sedimentary Rock: Spallanzani Crater

    NASA Technical Reports Server (NTRS)

    2001-01-01

    [figure removed for brevity, see original site]

    Although most of the best examples of layered sedimentary rock seen on Mars are found at equatorial and sub-tropical latitudes, a few locations seen at mid- and high-latitudes suggest that layered rocks are probably more common than we can actually see from orbit. One extremely good example of these 'atypical' layered rock exposures is found in the 72 km-diameter (45 miles) crater, Spallanzani (58.4oS, 273.5oW). Located southeast of Hellas Planitia, the crater is named for the 18th Century Italian biologist, Lazzaro Spallanzani (1729-1799). Picture A presents a composite of the best Viking orbiter image (VO2-504B55) of the region with 4 pictures obtained June 1999 through January 2001 by the Mars Global Surveyor Mars Orbiter Camera (MOC). Each MOC narrow angle image is 3 km across. Taken in the MOC's 'survey mode,' all four images were acquired at roughly 12 meters (39 ft) per pixel. Picture B zooms-in on the portion of the composite image that includes the 4 MOC images (the 100%-size view is 20 m (66 ft) per pixel). Other craters in the region near Spallanzani show features--at Viking Orbiter scale--that are reminiscent of the layering seen in Spallanzani. Exactly what these layers are made of and how they came to be where we see them today are mysteries, but it is possible that they are similar to the materials seen in the many craters and chasms of the equatorial latitudes on Mars.

  9. Electrodynamics of the high latitude middle atmosphere

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.

    1987-01-01

    Atmospheric electrodynamics is reviewed. The discovery of apparent large (V/m) electric fields within the mesosphere invites the possibility for this region to be electrically active. Observations of the V/m field were made at high latitudes even under active conditions, but always below heights where significant enhancements in electrical conductivity are found to occur. Two measurements at Andoya (Norway) show anticorrelation of horizontal field directions with wind directions, suggesting a mechanism which involves mechanical separation of charged aerosols. Reported evidence for such aerosols makes this concept more viable. Noctilucent clouds and mesospheric turbulence, and their influence on the local electrical environment are mentioned.

  10. A Mid-Latitude Scintillation Model.

    DTIC Science & Technology

    1986-10-31

    irregularities • that produce scintillation in the naturally disturbed mid-latitude F layer. The model will be incorporated into Program WBMOD , which includes... WBMOD ) which are operational at USAF Global Weather Central and at several other user locationsiwere based on extensive analysis of scintillation data...Latitudinal Variation 21 4.2.2 Diurnal Variation 23 4.2.3 Sunspot-number Dependence 23 4.2.4 VT Lead Constant 23 5 CONCLUSION 28 5.1 Efficacy of WBMOD 28 5.2

  11. Saturn Chorus as a Function of Latitude

    NASA Astrophysics Data System (ADS)

    Menietti, J. D.; Hospodarsky, G. B.; Gurnett, D. A.; Shprits, Y.

    2013-12-01

    Not only the dust but also the spatial scale of Saturn, including the background magnetic field inhomogeneity, make the study of whistler mode plasma wave emissions at Saturn quite different from Earth. The significant decrease in chorus intensity nearest the Saturn magnetic equator along a nearly constant L shell has already been reported. In the current study we analyze all known examples of these data and report the collective functional dependence of chorus intensity and wave normal angle, as well as density and magnetic inhomogeneity versus latitude. These values are important in the modeling of pitch angle scattering and possible electron acceleration at Saturn.

  12. Transient magnetic field signatures at high latitudes

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.

    1993-01-01

    We survey GOES 2/5/6 geosynchronous and Huancayo, Peru, ground magnetometer observations at the times of 70 transient (2-10 min) events recorded at South Pole Station, Antarctica. The simultaneous observations indicate that most South Pole events correspond to sudden sharp variations in the equatorial magnetospheric and low-latitude ground magnetic field. The exceptions occur when the South Pole events have weak amplitudes and/or Huancayo and GOES 2/5/6 are far from local noon. The corresponding features observed at GOES 5 and GOES 6 are generally similar, with a lag indicating antisunward motion. A similar antisunward motion may be inferred from the ground observations themselves. On a case-by-case and statistical basis, the characteristics of the events observed in South Pole ground magnetograms resemble those previously interpreted as sudden impulse and sudden storm commencement signatures at other high-latitude stations. These observations suggest that the transient events at South Pole form part of the magnetospheric and ionospheric response to a sudden change in the fraction of the solar wind dynamic pressure applied to the magnetosphere.

  13. Transient magnetic field signatures at high latitudes

    SciTech Connect

    Sibeck, D.G. )

    1993-01-01

    We survey GOES 2/5/6 geosynchronous and Huancayo, Peru, ground magnetometer observations at the times of 70 transient (2-10 min) events recorded at South Pole Station, Antarctica. The simultaneous observations indicate that most South Pole events correspond to sudden sharp variations in the equatorial magnetospheric and low-latitude ground magnetic field. The exceptions occur when the South Pole events have weak amplitudes and/or Huancayo and GOES 2/5/6 are far from local noon. The corresponding features observed at GOES 5 and GOES 6 are generally similar, with a lag indicating antisunward motion. A similar antisunward motion may be inferred from the ground observations themselves. On a case-by-case and statistical basis, the characteristics of the events observed in South Pole ground magnetograms resemble those previously interpreted as sudden impulse and sudden storm commencement signatures at other high-latitude stations. These observations suggest that the transient events at South Pole form part of the magnetospheric and ionospheric response to a sudden change in the fraction of the solar wind dynamic pressure applied to the magnetosphere. 57 refs., 14 figs.

  14. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  15. The role of latitude in mobilism debates.

    PubMed

    Irving, Edward

    2005-02-08

    In the early 1920s, the continental displacement theory of Wegener, latitude studies of Koppen and Wegener, and Argand's ideas on mountain building led to the first mobilistic paleogeography. In the 1930s and 1940s, many factors caused its general abandonment. Mobilism was revived in the 1950s and 1960s by measurements of long-term displacement of crustal blocks relative to each other (tectonic displacement) and to Earth's geographic pole (latitudinal displacement). Also, short-term or current displacements can now be measured. I briefly outline the categories of tectonic and current displacement and focus on latitudinal displacement. Integration of tectonic and latitudinal displacement in the early 1970s completed the new mobilistic paleogeography, in which the transformation of rock magnetization directions into paleopoles and latitudes and the finite rotation of spherical plates about pivot points play complementary roles; this new synthesis now provides a quantitative basis for studying long-term evolution of Earth's surface features and climate, the changing environments in which life evolves.

  16. Riparian plant litter quality increases with latitude.

    PubMed

    Boyero, Luz; Graça, Manuel A S; Tonin, Alan M; Pérez, Javier; J Swafford, Andrew; Ferreira, Verónica; Landeira-Dabarca, Andrea; A Alexandrou, Markos; Gessner, Mark O; McKie, Brendan G; Albariño, Ricardo J; Barmuta, Leon A; Callisto, Marcos; Chará, Julián; Chauvet, Eric; Colón-Gaud, Checo; Dudgeon, David; Encalada, Andrea C; Figueroa, Ricardo; Flecker, Alexander S; Fleituch, Tadeusz; Frainer, André; Gonçalves, José F; Helson, Julie E; Iwata, Tomoya; Mathooko, Jude; M'Erimba, Charles; Pringle, Catherine M; Ramírez, Alonso; Swan, Christopher M; Yule, Catherine M; Pearson, Richard G

    2017-09-05

    Plant litter represents a major basal resource in streams, where its decomposition is partly regulated by litter traits. Litter-trait variation may determine the latitudinal gradient in decomposition in streams, which is mainly microbial in the tropics and detritivore-mediated at high latitudes. However, this hypothesis remains untested, as we lack information on large-scale trait variation for riparian litter. Variation cannot easily be inferred from existing leaf-trait databases, since nutrient resorption can cause traits of litter and green leaves to diverge. Here we present the first global-scale assessment of riparian litter quality by determining latitudinal variation (spanning 107°) in litter traits (nutrient concentrations; physical and chemical defences) of 151 species from 24 regions and their relationships with environmental factors and phylogeny. We hypothesized that litter quality would increase with latitude (despite variation within regions) and traits would be correlated to produce 'syndromes' resulting from phylogeny and environmental variation. We found lower litter quality and higher nitrogen:phosphorus ratios in the tropics. Traits were linked but showed no phylogenetic signal, suggesting that syndromes were environmentally determined. Poorer litter quality and greater phosphorus limitation towards the equator may restrict detritivore-mediated decomposition, contributing to the predominance of microbial decomposers in tropical streams.

  17. Magnetospheric imaging of high latitude ion outflows

    NASA Technical Reports Server (NTRS)

    Garrido, D. E.; Robinson, R. M.; Chiu, Y. T.; Collin, H. L.; Smith, R. W.; Swift, D. W.

    1994-01-01

    High latitude ion outflows mostly consist of upward streaming O(+) and He(+) emanating from the ionosphere. At heights above 1000 km, these flows consist of cold and hot components which resonantly scatter solar extreme ultraviolet (EUV) light, however, the ion populations respond differently to Doppler shifting resulting from the large relative velocities between the ions and the Sun. The possibility of optical detection of the Doppler effect on the scattering rate will be discussed for the O(+) (83.4 nm) ions. We have contrasted the EUV solar resonance images of these outflows by simulations of the 30.4 nm He(+) and 83.4 nm O(+) emissions for both quiet and disturbed geomagnetic conditions. Input data for the 1000 km level has been obtained from the EICS instrument aboard the Dynamics Explorer (DE) satellite. Our results show emission rates of 50 and 56 milli-Rayleighs at 30.4 nm for quiet and disturbed conditions and 65 and 75 milli-Rayleighs at 83.4 nm for quiet and disturbed conditions, respectively, obtained for a polar orbiting satellite and viewing radially outward. We also find that an imager at an equatorial distance of 9 R(sub E) or more is in a favorable position for detecting ion outflows, particularly when the plasmapause is depressed in latitude. However, an occultation disk is necessary to obscure the bright plasmaspheric emissions.

  18. The role of latitude in mobilism debates

    PubMed Central

    Irving, Edward

    2005-01-01

    In the early 1920s, the continental displacement theory of Wegener, latitude studies of Köppen and Wegener, and Argand's ideas on mountain building led to the first mobilistic paleogeography. In the 1930s and 1940s, many factors caused its general abandonment. Mobilism was revived in the 1950s and 1960s by measurements of long-term displacement of crustal blocks relative to each other (tectonic displacement) and to Earth's geographic pole (latitudinal displacement). Also, short-term or current displacements can now be measured. I briefly outline the categories of tectonic and current displacement and focus on latitudinal displacement. Integration of tectonic and latitudinal displacement in the early 1970s completed the new mobilistic paleogeography, in which the transformation of rock magnetization directions into paleopoles and latitudes and the finite rotation of spherical plates about pivot points play complementary roles; this new synthesis now provides a quantitative basis for studying long-term evolution of Earth's surface features and climate, the changing environments in which life evolves. PMID:15684058

  19. Paleogeographic implications of high latitude and middle latitude affinities of the ammonoid Uraloceras

    SciTech Connect

    Spinosa, C.; Gallegos, D.M. ); Nassichuk, W.W. ); Snyder, W.S.

    1991-02-01

    The ammonoid genus Uraloceras characterized a Lower Permian Boreal paleogeographic realm. Reported Lower Permian Pangaean uraloceras occurrences have a Boreal or high-latitude distribution. Additional Lower Permian occurrences in Alaska, dominated by Boreal species, are compatible with and reinforce the Boreal distribution of the genus. In contrast, a new Uraloceras species from Nevada and from the Yukon, as well as representatives of the genus form Nei Monggol, inhabited regions of lower latitudes. The latter ammonoid faunas, geographically and paleoecologically transitional between boreal and equatorial realms, include the genus Uraloceras as well as abundant other ammonoid taxa and representatives of equatorial perinitid ammonoids. The lower assemblage of Wrangellia terrane in eastern Alaska, consisting of the Lower Permian Mankomen Group (Slana Spur and Eagle Creek formations), contains abundant Uraloceras and Paragastrioceras of high-latitude affinities. Published paleomagnetic data indicate that the Nikolai Greenstone is of equatorial origin, with paleolatitudes 10 to 17{degree}. The Nikolai Greenstone seems to have a far-traveled history incompatible with ammonoid evidence suggesting cool-water setting on the Pangaean continental shelf. A reinterpretation for the origin of Wrangellia or its magnetic signature may be in order. Alternative hypotheses suggest that the Eagle Creek Uraloceras-Paragastrioceras Boreal fauna was scraped off the craton at higher latitudes (possible 30-45{degree}) and carried with Wrangellia to its present location.

  20. A high-latitude, low-latitude boundary layer model of the convection current system

    SciTech Connect

    Siscoe, G.L. ); Lotko, W.; Sonnerup, B.U.O. )

    1991-03-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer ({approximately}1000 km), whereas thicknesses inferred from satellite data tend to be greater.

  1. High latitude electromagnetic plasma wave emissions

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  2. EGRET sources at intermediate galactic latitude

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P. (Principal Investigator)

    1996-01-01

    This paper presents the abstracts of four papers (using ROSAT data) that are submitted to refereed journals during the current reporting period. The papers are: (1) Extreme x-ray variability in the narrow-line QSO PHL 1092; (2) The Geminga pulsar (soft x-ray variability and an EUVE observation); (3) a broad-band x-ray study of the geminga pulsar; and (4) Classification of IRAS-selected x-ray galaxies in the ROSAT all-sky survey. The abstracts of these papers are given in the next four sections of this report, and their status is given in the Appendix. Finally, two new projects (De-identifying a non-AGN and EGRET sources at intermediate galactic latitude) for which ROSAT data were recently received are currently being studied under this grant. A summary of work in progress on these new projects is given in the last two sections of this report.

  3. High latitude electromagnetic plasma wave emissions

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  4. Electrodynamics of ionospheric weather over low latitudes

    NASA Astrophysics Data System (ADS)

    Abdu, Mangalathayil Ali

    2016-12-01

    The dynamic state of the ionosphere at low latitudes is largely controlled by electric fields originating from dynamo actions by atmospheric waves propagating from below and the solar wind-magnetosphere interaction from above. These electric fields cause structuring of the ionosphere in wide ranging spatial and temporal scales that impact on space-based communication and navigation systems constituting an important segment of our technology-based day-to-day lives. The largest of the ionosphere structures, the equatorial ionization anomaly, with global maximum of plasma densities can cause propagation delays on the GNSS signals. The sunset electrodynamics is responsible for the generation of plasma bubble wide spectrum irregularities that can cause scintillation or even disruptions of satellite communication/navigation signals. Driven basically by upward propagating tides, these electric fields can suffer significant modulations from perturbation winds due to gravity waves, planetary/Kelvin waves, and non-migrating tides, as recent observational and modeling results have demonstrated. The changing state of the plasma distribution arising from these highly variable electric fields constitutes an important component of the ionospheric weather disturbances. Another, often dominating, component arises from solar disturbances when coronal mass ejection (CME) interaction with the earth's magnetosphere results in energy transport to low latitudes in the form of storm time prompt penetration electric fields and thermospheric disturbance winds. As a result, drastic modifications can occur in the form of layer restructuring (Es-, F3 layers etc.), large total electron content (TEC) enhancements, equatorial ionization anomaly (EIA) latitudinal expansion/contraction, anomalous polarization electric fields/vertical drifts, enhanced growth/suppression of plasma structuring, etc. A brief review of our current understanding of the ionospheric weather variations and the

  5. Revisiting the question: Does high-latitude solar activity lead low-latitude solar activity in time phase?

    SciTech Connect

    Kong, D. F.; Qu, Z. N.; Guo, Q. L.

    2014-05-01

    Cross-correlation analysis and wavelet transform methods are used to investigate whether high-latitude solar activity leads low-latitude solar activity in time phase or not, using the data of the Carte Synoptique solar filaments archive from 1919 March to 1989 December. From the cross-correlation analysis, high-latitude solar filaments have a time lead of 12 Carrington solar rotations with respect to low-latitude ones. Both the cross-wavelet transform and wavelet coherence indicate that high-latitude solar filaments lead low-latitude ones in time phase. Furthermore, low-latitude solar activity is better correlated with high-latitude solar activity of the previous cycle than with that of the following cycle, which is statistically significant. Thus, the present study confirms that high-latitude solar activity in the polar regions is indeed better correlated with the low-latitude solar activity of the following cycle than with that of the previous cycle, namely, leading in time phase.

  6. Canadian Space Launch: Exploiting Northern Latitudes For Efficient Space Launch

    DTIC Science & Technology

    2015-04-01

    an orbit directly over the North Pole. Is it more efficient to launch HIOs from higher latitudes ? In order to proceed with an investigation into... North American launch capacity with similar 15 latitudes to Russian facilities would be a welcomed alternative for commercial space companies...northern Manitoba. The high latitude of this site of approximately 59 o and remote location Figure 6 19 would allow for efficient polar launches

  7. Latitude and local time dependence of precipitated low energy electrons at high latitudes

    NASA Technical Reports Server (NTRS)

    Gustafsson, G.

    1972-01-01

    Data from particle detectors on board the satellite OGO-4 were used to study the precipitation of electrons in the energy range 0.7 to 24 keV. The latitude dependence of these particles in the local time region from midnight to dawn was investigated in detail. The analysis shows that the precipitation of particles of energies 2.3 to 24 keV is centered at an invariant latitude of about 68 deg at midnight with a clear shift in latitude with increasing local time and this shift is more pronounced for lower energies. The highest fluxes of particles in this energy interval are measured at midnight and they decrease rapidly with local time. The data in the energy range 2.3 to 24 keV support a theory where particles are injected in the midnight region from the tail gaining energy due to a betatron process and then drift eastwards in a combined electric and magnetic field. The main part of the electrons at 0.7 keV show a different behavior. They seem to undergo an acceleration process which is rather local, sometimes giving field aligned fluxes which may be super-imposed on the background precipitation.

  8. Faint high-latitude carbon stars

    NASA Astrophysics Data System (ADS)

    Green, Paul Jonathan

    We have undertaken a wide area survey to search for faint high latitude carbon (FHLC) stars. Carbon giants are ideal for study of the structure and kinematics of the outer galactic halo. We use two color photometric selection with large format charge-coupled devices (CCD's) to cover 52 deg2 of sky to a depth of about V = 18. Below this limit, we find good (approximately less than 20 percent) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Soneira at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch. Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan system as warm (color class less than 3). Of 94 faint C star candidates from our own CCD survey, one highly ranked V = 17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V = 18, the surface density FHLC stars is 0.019+0.044-.016 deg-2. We identify two FHLC stars with previously catalogued high proper motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions in the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper motion survey, spanning a 30 year baseline, thus identifies two new dC's, and provides proper motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population 2 dC's will have detectable proper motions in a survey as sensitive as our own, and that to a limit of V approximately

  9. Faint High-Latitude Carbon Stars

    NASA Astrophysics Data System (ADS)

    Green, Paul J.

    1992-10-01

    Since carbon giants are ideal for study of the structure and kinematics of the outer galactic halo, we have undertaken a wide-area survey to search for faint high-latitude carbon (FHLC) stars. We use two-color photometric selection with large format CCDs to cover 52 deg^2 of sky to a depth of about V=18. Below this limit, we find good (< 20%) agreement between our object counts as a function of magnitude and the galactic models of Bahcall and Coneira (1984) at a variety of latitudes and longitudes. Our spectroscopic followup began with low-resolution spectra of 19 unconfirmed C-star candidates from the Case objective-prism photographic survey of Sanduleak and Pesch (1988). Four of these we find to be M stars. The 15 C stars we classify on the two-parameter Keenan-Morgan (1941) system as warm (color class < 4), with moderate to weak carbon band strengths (C class < 3). Of 94 faint C-star candidates from our own CCD survey, one highly ranked V=17 candidate was found to have strong carbon and CN bands. We estimate that to a depth of V=18, the surface density of FHLC stars is 0.019^0.044_-0.016 deg^-2. We identify two FHLC stars with previously cataloged high-proper-motion objects. These objects are thus inferred to be dwarf carbon (dC) stars, supplementing the one previously known case, G 77-61. Not all dC stars will have detectable proper motions, so other luminosity/distance indicators are needed: we find that C dwarfs all have similar JHK colors, and possibly an unusually strong lambda-6191 bandhead of carbon. By comparing positions of the HST Guide Star Catalog and the original Palomar Observatory Sky Survey, we detect proper motions in two additional FHLC stars. Our proper-motion survey, spanning a 30-yr base line, thus identifies four new dC's, and provides proper-motion upper limits for another 44 FHLC stars. Kinematic simulations suggest that virtually all Population II dCs will have detectable proper motions in a survey as sensitive as our own, and that to a

  10. [Valutazione delle guardie di sicurezza privata attraverso la Suicide Probability Scale e la Brief Symptom Inventory].

    PubMed

    Dogan, Bulent; Canturk, Gurol; Canturk, Nergis; Guney, Sevgi; Özcan, Ebru

    2016-01-01

    RIASSUNTO. Scopo. Lo scopo di questo studio è stato quello di investigare l'influenza della probabilità di suicidio, con le sue caratteristiche sociodemografiche, e di procurare i dati per la prevenzione del suicidio tra le guardie di sicurezza privata che lavorano in condizioni di stress, essendo a contatto ininterrottamente con eventi negativi e traumatici di vita durante il loro lavoro. Metodi. Hanno partecipato allo studio 200 guardie di sicurezza privata e 200 persone dell'Università di Ankara. Per raccogliere i dati sono stati utilizzati un questionario riguardante le condizioni sociodemografiche dei partecipanti, la Suicide Probability Scale (SPS) e la Brief Symptom Inventory (BSI). Risultati. Genere, stato civile, stipendio, credenze religiose, vivere una situazione di pericolo di vita, passato di tentativi di suicidio, fumare e non avere una malattia cronica hanno causato statisticamente una differenza significativa sui punteggi di SPS tra il gruppo di guardie di sicurezza privata e quello di controllo. In aggiunta, c'è stata una correlazione positiva statisticamente significativa tra i punteggi totali delle sottoscale di SPS e quelli di BSI. Conclusioni. Allo stesso modo degli agenti di polizia e dei gendarmi, le guardie di sicurezza privata sono ad alto rischio di commettere e tentare il suicidio trovandosi in condizioni stressanti di lavoro e anche soffrendo del trauma secondario. È necessario che essi siano consapevoli della propria tendenza al suicidio e avere controlli psichiatrici regolari.

  11. Mountains and arid climates of middle latitudes

    SciTech Connect

    Manabe, S.; Broccoli, A.J. )

    1990-01-12

    Simulations from a global climate model with and without orography have been used to investigate the role of mountains in maintaining extensive arid climates in middle latitudes of the Northern hemisphere. Dry climates similar to those observed were simulated over central Asia and western interior North America in the experiment with mountains, whereas relatively moist climates were simulated in these areas in the absence of orography. The experiments suggest that these interior regions are dry because general subsidence and relatively infrequent storm development occur upstream of orographically induced stationary wave troughs. Downstream of these troughs, precipitation-bearing storms develop frequently in association with strong jet streams. In contrast, both atmospheric circulation and precipitation were more zonally symmetric in the experiment without mountains. In addition, orography reduces the moisture transport into the continental interiors from nearby oceanic sources. The relative soil wetness of these regions in the experiment without mountains is consistent with paleoclimatic evidence of less aridity during the late Tertiary, before substantial uplift of the Rocky Mountains and Tibetan Plateau is believed to have occurred.

  12. Bayesian Image Classification At High Latitudes

    NASA Astrophysics Data System (ADS)

    Bulgin, Claire E.; Eastwood, Steinar; Merchant, Chris J.

    2013-12-01

    The European Space Agency created the Climate Change Initiative (CCI) to maximize the usefulness of Earth Observations to climate science. Sea Surface Temperature (SST) is an essential climate variable to which satellite observations make a crucial contribution, and is one of the projects within the CCI program. SST retrieval is dependent on successful cloud clearing and identification of clear-sky pixels over ocean. At high latitudes image classification is more difficult due to the presence of sea-ice. Newly formed ice has a temperature close to the freezing point of water and a dark surface making it difficult to distinguish from open ocean using data at visible and infrared wavelengths. Similarly, melt ponds on the sea-ice surface make image classification more difficult. We present here a three- way Bayesian classifier for the AATSR instrument classifying pixels as ‘clear-sky over ocean', ‘clear-sky over ice' or ‘cloud' using the 0.6, 1.6, 11 and 12 micron channels. We demonstrate the ability of the classifier to successfully identify sea-ice and consider the potential for generating an ice surface temperature record from AATSR which could be extended using data from SLSTR.

  13. Empirical models of high latitude electric fields

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1976-01-01

    Model cross sections of the high latitude dawn-dusk electric field based on OGO-6 data are presented for the signature profiles, most frequently encountered for both + and -Y orientations of the interplanetary magnetic field. Line integrals give a total potential of 76 keV in each case. To illustrate extremes, examples of model cross-sections with total potentials of 23 keV and 140 keV are also given. Model convection patterns are also presented utilizing OGO-6 data on boundary locations at other magnetic local times. When this information is combined with characteristic field geometries in the region of the Harang discontinuity, and is supplemented by data from Ba+ cloud motions in the polar cap, it becomes possible to construct realistic convection patterns on the nightside which deviate from the usual sun-aligned patterns. The observational models presented are of limited applicability as a consequence of the variability of observed distributions. These limitations are emphasized with particular attention given to several types of recurrent deviations which have not previously been discussed.

  14. Low latitude middle atmosphere ionization studies

    NASA Technical Reports Server (NTRS)

    Bassi, J. P.

    1976-01-01

    Low latitude middle atmosphere ionization was studied with data obtained from three blunt conductivity probes and one Gerdien condenser. An investigation was conducted into the effects of various ionization sources in the 40 to 65 Km altitude range. An observed enhancement of positive ion conductivity taking place during the night can be explained by an atmsopheric effect, with cosmic rays being the only source of ionization only if the ion-ion recombination coefficient (alpha sub i) is small(10 to the -7 power cu cm/s) and varies greatly with altitude. More generally accepted values of alpha sub i ( approximately equal to 3x10 to the -7 power cu cm/s) require an additional source of ionization peaking at about 65 Km, and corresponding approximately to the integrated effect of an X-ray flux measured on a rocket flown in conjunction with the ionization measurements. The reasonable assumption of an alpha sub i which does not vary with altitude in the 50-70 Km range implies an even greater value alpha sub i and a more intense and harder X-ray spectrum.

  15. Radioxenon background at high northern latitudes

    NASA Astrophysics Data System (ADS)

    Saey, Paul R. J.; Wotawa, Gerhard; de Geer, Lars-Erik; Axelsson, Anders; Bean, Marc; D'Amours, Real; Elmgren, Klas; Peterson, Jenny; Ringbom, Anders; Stocki, Trevor J.; Ungar, R. K.

    2006-09-01

    As part of the International Noble Gas Experiment (INGE) two stations were deployed in remote regions at high northern latitudes: Longyearbyen, Spitsbergen, Norway (78.2°N), and Yellowknife, Canada (62.5°N). With one exception, both stations are 2000 km or more from any single known stationary nuclear facility. Nevertheless, the short-lived anthropogenic radionuclide ? = 5.24 days) has been detected on a regular basis at both stations, and also ? = 11.84 days) was found at the Yellowknife station. Measuring these very low concentrations (˜0.1 mBq/m3) has been possible because of the introduction of new and sensitive equipment developed specifically for the verification of the Comprehensive Nuclear-Test Ban Treaty. By means of atmospheric transport modeling, it was determined that the measurements at both sites are broadly consistent with reported releases from reactors in North America and Europe and that the Spitsbergen station is much more susceptible to this influence than the Yellowknife station. Especially at Spitsbergen, the simplified assumption of a continuous bulk release across Europe could well explain the month-to-month variation of the time series. A future radioxenon event classification scheme for treaty verification purposes thus needs to consider the actual meteorological situation and large-scale transport processes.

  16. Latitude: How American Astronomers Solved the Mystery of Variation

    NASA Astrophysics Data System (ADS)

    Ray, Richard D.

    First longitude, now latitude. From Latitude's title we cannot help thinking of Dava Sobel's recent bestseller, Longitude. I suppose it's unlikely to be such a moneymaker, but this delightful new book by Bill and Merri Sue Carter, a father and daughter team, is similar to Sobel's book. Both are physically small, with short chapters, which makes for a quick read. And both have a clear hero: John Harrison and his chronometers for longitude; and Seth Carlo Chandler Jr. and his almucantar for latitude. Both books eschew academic-style footnoting, although Latitude does list a few useful sources for each chapter and provides a comprehensive list of Chandler's astronomical publications. Chandler's name is known to most AGU members for its association with the 14-month wobble of the Earth's pole. He also discovered the slightly smaller annual wobble, and an argument can be made that he was the principal discoverer of polar motion, or latitude variation, in general.

  17. Characteristics of High Latitude Precursor Flows Ahead of Dipolarization Fronts

    NASA Astrophysics Data System (ADS)

    Li, J. Z.; Zhou, X.; Angelopoulos, V.; Liu, J.; Runov, A.; Pan, D.; Zong, Q.

    2016-12-01

    Dipolarization fronts (DFs), earthward-propagating structures in the magnetotail current sheet characterized by sharp enhancements of northward magnetic field, are capable of converting electromagnetic energy into particles' kinetic energy. The accelerated and heated ions form plasma flows ahead of DFs, which have been identified as DF precursor flows in both high- and low-latitude plasma sheet. Statistics from THEMIS (Time History of Events and Macroscale Interactions during Substorms) observations have shown that the particle and energy fluxes towards the Earth are remarkably larger in high latitude than in low latitude. Moreover, the high-latitude particle and energy fluxes at the DF dawnside are remarkably greater than those at the duskside, which is opposite to the dawn-dusk asymmetries near the equatorial region. These latitude-dependent characteristics of DF precursor flows are reproduced by a simple Liouville-mapping simulation, which provides new understandings of ion dynamics associated with dipolarization fronts.

  18. Viewing Indians: Native Encounters with Power, Tourism, and the Camera in the Wisconsin Dells, 1866-1907

    ERIC Educational Resources Information Center

    Hoelscher, Steven

    2003-01-01

    In the winter of 1883, the photographer H. H. Bennett decided to spice up his descriptive catalogue of stereo views with something new. Several years earlier, a simple listing of his photographs--mostly landscape views of the area surrounding the Wisconsin River Dells--brought the small-town studio photographer considerable renown and enhanced…

  19. Viewing Indians: Native Encounters with Power, Tourism, and the Camera in the Wisconsin Dells, 1866-1907

    ERIC Educational Resources Information Center

    Hoelscher, Steven

    2003-01-01

    In the winter of 1883, the photographer H. H. Bennett decided to spice up his descriptive catalogue of stereo views with something new. Several years earlier, a simple listing of his photographs--mostly landscape views of the area surrounding the Wisconsin River Dells--brought the small-town studio photographer considerable renown and enhanced…

  20. Reach a New Threshold of Freedom and Control with Dell's Flexible Computing Solution: On-Demand Desktop Streaming

    ERIC Educational Resources Information Center

    Technology & Learning, 2008

    2008-01-01

    When it comes to IT, there has always been an important link between data center control and client flexibility. As computing power increases, so do the potentially crippling threats to security, productivity and financial stability. This article talks about Dell's On-Demand Desktop Streaming solution which is designed to centralize complete…

  1. Reach a New Threshold of Freedom and Control with Dell's Flexible Computing Solution: On-Demand Desktop Streaming

    ERIC Educational Resources Information Center

    Technology & Learning, 2008

    2008-01-01

    When it comes to IT, there has always been an important link between data center control and client flexibility. As computing power increases, so do the potentially crippling threats to security, productivity and financial stability. This article talks about Dell's On-Demand Desktop Streaming solution which is designed to centralize complete…

  2. Motion of the Heliospheric Termination Shock at High Heliographic Latitude

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron

    1995-01-01

    We expect the mean distance of the heliospheric termination shock to be greater (smaller) at polar latitudes than at equatorial latitudes, depending on whether the mean dynamic pressure of the solar wind is greater or smaller at high latitudes. The heliospheric termination shock is expected to move in response to variation in upstream solar wind conditions, so that at any particular instant the termination shock will resemble a distorted asymmetric balloon with some parts moving inward and others moving outward. If the shock is a gasdynamic or magnetohydrodynamic shock the results of the analysis depend only very weakly on the nature of the upstream disturbance; typical speeds of the disturbed shock are approximately 100 to 200 km/s. In the absence of a significant latitude gradient of the typical magnitude of solar wind disturbances typical motions of the disturbed shock at polar latitudes would be about twice as fast, due to the higher speed of the high-latitude wind. If the dynamics of the termination shock are dominated by acceleration of the anomalous component of the cosmic rays, the motion of the shock in response to a given disturbance is substantially slower than in the gasdynamic case. Conceivably, particle acceleration might be a less important effect at higher latitudes, and we envision the possibility of a termination shock that is dominated by particle acceleration at lower latitudes and is an MHD shock at high latitudes. In this event high latitude solar wind disturbances would produce substantially larger inward and outward motions of the shock in the polar regions.

  3. Carbon cycling in high-latitude ecosystems

    NASA Technical Reports Server (NTRS)

    Townsend, Alan; Frolking, Stephen; Holland, Elizabeth

    1992-01-01

    The carbon-rich soils and peatlands of high-latitude ecosystems could substantially influence atmospheric concentrations of CO2 and CH4 in a changing climate. Currently, cold, often waterlogged conditions retard decomposition, and release of carbon back to the atmosphere may be further slowed by physical protection of organic matter in permafrost. As a result, many northern ecosystems accumulate carbon over time (Billings et al., 1982; Poole and Miller, 1982), and although such rates of accumulation are low, thousands of years of development have left Arctic ecosystems with an extremely high soil carbon content; Schlesinger's (1984) average value of 20.4 kg C/m(sup 2) leads to a global estimate of 163 x 10(exp 15) g C. All GCM simulations of a doubled CO2 climate predict the greatest warming to occur in the polar regions (Dickinson, 1986; Mitchell, 1989). Given the extensive northern carbon pools and the strong sensitivity of decomposition processes to temperature, even a slight warming of the soil could dramatically alter the carbon balance of Arctic ecosystems. If warming accelerates rates of decomposition more than rates of primary production, a sizeable additional accumulation of CO2 in the atmosphere could occur. Furthermore, CH4 produced in anaerobic soils and peatlands of the Arctic already composes a good percentage of the global efflux (Cicerone and Oremlund, 1988); if northern soils become warmer and wetter as a whole, CH4 emissions could dramatically rise. A robust understanding of the primary controls of carbon fluxes in Arctic ecosystems is critical. As a framework for a systematic examination of these controls, we discussed a conceptual model of regional-scale Arctic carbon turnover, including CH4 production, and based upon the Century soil organic matter model.

  4. Ulysses observations of latitude gradients in the heliospheric magnetic field

    NASA Technical Reports Server (NTRS)

    Smith, E. J.; Balogh, A.; Lepping, R. P.; Neugebauer, M.; Phillips, J.; Tsurutani, B. T.

    1995-01-01

    Several parameters measured by Ulysses as it traveled southward to heliographic latitudes of -50 deg are presented and analyzed. The radial component of the magnetic field, averaged over 5 deg latitude increments and extrapolated back to 1 AU, is found to agree with baseline measurements provided by IMP-8. There is little, if any, evidence of a latitude gradient, a result consistent with the dominance of the magnetic field associated with the heliospheric current sheet and with recent models which include the effect of the current sheet as well as of source surface fields. Thus far, the spiral angle agrees with the Parker spiral assuming a rate of rotation of the field lines at the Sun equal to the equatorial value. No evidence is seen of either a change in rotation rate with latitude or an unwinding of the spiral as suggested by a recent analysis. Hourly variances in the field magnitude and in the sum of the variances in the components, normalized to the square of the observed field strenght, show the former to be independent of latitude while the latter shows a strong increase with latitude. These two observations are shown to be associated with Alfven waves that are continuously present at high latitudes. The waves have large amplitudes, extend to long periods, and have important implications for galactic cosmic rays and the solar wind.

  5. The low-latitude Rapitan glaciation (Invited)

    NASA Astrophysics Data System (ADS)

    MacDonald, F. A.; Schmitz, M. D.; Crowley, J. L.; Roots, C.; Maloof, A. C.; Jones, D. S.; Strauss, J.

    2009-12-01

    The snowball Earth hypothesis1 was developed in response to strong palaeomagnetic evidence for low-latitude glaciation from “Marinoan” glacial deposits in the Elatina Formation of Australia. An earlier Cryogenian glaciation, commonly referred to as the “Sturtian” glaciation, has been inferred from the ubiquity of pre-Marinoan glacial deposits; however, the synchroneity and global extent of this event have been questioned due to the lack of precise U/Pb ages and robust paleomagnetic data. Herein we provide new age constraints on the Franklin LIP with revised U/Pb ID-TIMS dates on the the Mt. Harper volcanic complex in the Yukon Territory and the Coronation sills of Victoria Island. Furthermore we present a new age from a tuff interbedded with diamictite in the Upper Mt. Harper Group. A glaciogenic origin of the diamictites is provided by striated clasts and laminae-penetrating dropstones. These glacial deposits can be traced from Alaska westward through the Yukon Territory and into the Northwest Territories, and are correlative to the Rapitan Group. Throughout the Cordillera, the Rapitan Group and its correlatives commonly host iron formation, are the lower of two Cryogenian glacial horizons, and globally are thought to be equivalent to the Sturtian glaciation. The age of the tuff interbedded with the glacial deposits in the Mt. Harper Group is within 1 million years of the revised age on the Franklin LIP. Several paleomagnetic studies on dikes, sills, and basalts spanning >2000 km of NW Canada have agreed that the Franklin LIP erupted when NW Laurentia was in an equatorial position2,3. Consequently, the Sturtian glaciation on Laurentia can now be confidently inferred to have occurred at a very low palaeolatitude. Thus, there were at least two Cryogenian glaciations of global extent. 1 Kirschvink, J.L., in The Proterozoic Biosphere, edited by J. W. Schopf and C. Klein (Cambridge University Press, Cambridge, 1992), pp. 51. 2 Park, J.K., Paleomagnetic

  6. Transionospheric HF Propagation Experiments at Auroral Latitudes

    NASA Astrophysics Data System (ADS)

    James, H. G.; Benson, R. F.

    2004-05-01

    High-frequency (HF) propagation experiments are planned as part of the Enhanced Polar Outflow Probe (ePOP) satellite mission to be launched for the Canadian Space Agency in 2007. Ground transmitters such as the CADI ionosondes and the SuperDARN radars will be operated collaboratively to emit waves for detection by the Radio Receiver Instrument of ePOP during passes in the vicinity. The scientific goals include improved understanding of F-region morphology and dynamics, wave scattering and microphysical plasma processes. Partly as preparation for ePOP, transionospheric HF propagation data recorded by the receivers of the ISIS-I and ISIS-II spacecraft are being analyzed. The measurements were made in spring-summer 1978. A ground transmitter was built in Ottawa especially for the project. Some of the ISIS data were obtained in digital form from http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html. These digital data are being surveyed in an attempt to establish repeatable propagation characteristics. From these characteristics, the goal is to understand the processes experienced by waves passing through the ionosphere. Several tens of ISIS-II passes recorded at a fixed frequency of 9.303 MHz have been examined. Swept-frequency ionograms interleaved with these fixed-frequency measurements allow two-dimensional electron density distributions to be modeled in altitude and latitude. Computer code has been developed for three-dimensional ray tracing. The computed latitudinal extent of the zone irradiated at the ISIS-II altitude is approximately as observed. Within this "iris" of accessibility, the peak intensity of waves recorded at the spacecraft is within about 10 dB of what is computed with a link calculation. This calculation is based on a model for the 1-kW transmitter, a radiant-transfer calculation that follows the focusing/defocusing of rays using a three-ray pencil between ground and the satellite, and the orientation of the sounder receiving dipole. Poleward

  7. Effect of high latitude filtering on NWP skill

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Takacs, L. L.; Hoffman, R. N.

    1984-01-01

    The high latitude filtering techniques commonly employed in global grid point models to eliminate the high frequency waves associated with the convergence of meridians, can introduce serious distortions which ultimately affect the solution at all latitudes. Experiments completed so far with the 4 deg x 5 deg, 9-level GLAS Fourth Order Model indicate that the high latitude filter currently in operation affects only minimally its forecasting skill. In one case, however, the use of pressure gradient filter significantly improved the forecast. Three day forecasts with the pressure gradient and operational filters are compared as are 5-day forecasts with no filter.

  8. Quiet geomagnetic field representation for all days and latitudes

    USGS Publications Warehouse

    Campbell, W.H.; Schiffmacher, E.R.; Arora, B.R.

    1992-01-01

    Describes a technique for obtaining the quiet-time geomagnetic field variation expected for all days of the year and distribution of latitudes from a limited set of selected quiet days within a year at a discrete set of locations. A data set of observatories near 75??E longitude was used as illustration. The method relies upon spatial smoothing of the decomposed spectral components. An evaluation of the fidelity of the resulting model shows correlation coefficients usually above 0.9 at the lower latitudes and near 0.7 at the higher latitudes with variations identified as dependent upon season and field element. -from Authors

  9. High Winds in the Jovian Mid-latitudes

    NASA Image and Video Library

    1999-03-06

    A high resolution image of the Jovian mid-latitudes taken by NASA Voyager 1 spacecraft on March 2, 1979, shows distinctly differing characteristics of the planet meteorology. http://photojournal.jpl.nasa.gov/catalog/PIA00360

  10. Change in Mars Mid-Latitude Ionosphere After Comet Flyby

    NASA Image and Video Library

    2014-11-07

    These plots portray data from radar sounding of Mars mid-latitude ionosphere at three times on Oct. 19 and 20, 2014. The data are from the MARSIS instrument on the European Space Agency Mars Express orbiter.

  11. Glacial Ice Deposits in Mid-Latitudes of Mars

    NASA Image and Video Library

    2010-03-02

    NASA Mars Reconnaissance Orbiter has detected widespread deposits of glacial ice in the mid-latitudes of Mars. This map of a region known as Deuteronilus Mensae, in the northern hemisphere, shows locations of the detected ice deposits in blue.

  12. Sources of Low-latitude Ionospheric Electric-field Disturbances

    NASA Astrophysics Data System (ADS)

    Richmond, A. D.; Peymirat, C.

    2001-12-01

    Storm-time ionospheric electric-field disturbances at middle and low latitudes are generated both by direct magnetosphere-ionosphere interactions at high latitudes and by secondary effects of disturbance thermospheric winds. These disturbance electric fields can have a strong influence on the equatorial ionosphere. Using the NCAR Magnetosphere-Thermosphere-Ionosphere-Electrodynamics General Circulation Model (MTIEGCM), we simulate low-latitude electric-field disturbances associated with direct penetration from high latitudes and with secondary generation by disturbed thermospheric winds. The simulations display a number of features observed in equatorial electric fields on time scales of minutes to hours. Models like the MTIEGCM, together with simultaneous global observations of ionospheric electric fields and thermospheric winds, can help clarify the relative importance of the different mechanisms that produce ionospheric disturbances.

  13. High-latitude E and F region ionospheric predictions

    NASA Technical Reports Server (NTRS)

    Hunsucker, R. D.; Allen, R.; Argo, P. E.; Babcock, R.; Bakshi, P.; Lund, D.; Matsushita, S.; Smith, G.; Shirochkov, A. V.; Wortham, G.

    1979-01-01

    The physical processes and morphology of the high latitude E and F layers are discussed. The existence and adequacy of models, and features to be included are examined, as well as reliability of ionospheric predictions.

  14. Ulysses solar wind plasma observations at high southerly latitudes.

    PubMed

    Phillips, J L; Bame, S J; Feldman, W C; Gosling, J T; Hammond, C M; McComas, D J; Goldstein, B E; Neugebauer, M; Scime, E E; Suess, S T

    1995-05-19

    Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.

  15. Widespread Low-Latitude Diurnal CO2 Frost on Mars

    NASA Astrophysics Data System (ADS)

    Piqueux, S.; Kleinböhl, A.; Hayne, P. O.; Heavens, N. G.; Kass, D. M.; McCleese, D. J.; Schofield, J. T.; Shirley, J. H.

    2016-09-01

    We map and characterize MCS nighttime surface temperature observations consistent with the occurrence of CO2 frost on Mars. Low-latitude nighttime CO2 frost is widespread, with potential implications for the physical nature of the surface layer.

  16. Map of Martian Silicon at Mid-Latitudes

    NASA Image and Video Library

    2003-03-13

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element silicon. Silicon is one of the most abundant elements on the surface of both Mars and Earth (second only to oxygen). The most extensive region of highest silicon content, shown in red, is located in the high latitudes north of Tharsis (centered near 45 degrees latitude, -120 degrees longitude). The area of lowest silicon content, shown in blue, lies just to the east of the Hellas Basin (-45 degrees latitude, 90 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south. http://photojournal.jpl.nasa.gov/catalog/PIA04256

  17. High-latitude E and F region ionospheric predictions

    NASA Technical Reports Server (NTRS)

    Hunsucker, R. D.; Allen, R.; Argo, P. E.; Babcock, R.; Bakshi, P.; Lund, D.; Matsushita, S.; Smith, G.; Shirochkov, A. V.; Wortham, G.

    1979-01-01

    The physical processes and morphology of the high latitude E and F layers are discussed. The existence and adequacy of models, and features to be included are examined, as well as reliability of ionospheric predictions.

  18. The Active Latitudes of HAT-P-11

    NASA Astrophysics Data System (ADS)

    Morris, Brett; Hebb, Leslie; Davenport, James R. A.; Hawley, Suzanne L.

    2017-01-01

    Transiting planets map the brightness of their host stars, as the flux lost during exoplanet transits is proportional to the integrated flux occulted by the planet. We analyze four years of Kepler short-cadence photometry of HAT-P-11 - an active K4 dwarf with a 29 day rotation period, orbited by a hot-Neptune. Due to its highly-misaligned orbit, the planet occults most stellar latitudes during each transit, and the latitude distribution of spots is encoded in the transit light curves. We model each spot occultation in transit to create a spot map of HAT-P-11, which reveals two active latitudes near ±17 degrees. We investigate whether the spot distribution changes in time, and we compare the spot latitude distributions of HAT-P-11 and the Sun throughout the solar activity cycle.

  19. Shallow water simulations of Saturn's giant storms at different latitudes

    NASA Astrophysics Data System (ADS)

    García-Melendo, E.; Sánchez-Lavega, A.

    2017-04-01

    Shallow water simulations are used to present a unified study of three major storms on Saturn (nicknamed as Great White Spots, GWS) at different latitudes, polar (1960), equatorial (1990), and mid-latitude (2010) (Sánchez-Lavega, 2004; Sánchez-Lavega et al., 2011). In our model, the three GWS are initiated by introducing a Gaussian function pulse at the latitude of the observed phenomena with controlled horizontal size and amplitude. This function represents the convective source that has been observed to trigger the storm. A growing disturbance forms when the pulse reacts to ambient winds, expanding zonally along the latitude band of the considered domain. We then compare the modeled potential vorticity with the cloud field, adjusting the model parameters to visually get the closest aspect between simulations and observations. Simulations of the 2010 GWS (planetographic latitude ∼+40º, zonal velocity of the source ∼-30 m s-1) indicate that the Coriolis forces and the wind profile structure shape the disturbance generating, as observed, a long region to the east of the convective source with a high speed peripheral anticyclonic circulation, and a long-lived anticyclonic compact vortex accompanied by strong zonal advection on the southern part of the storm forming a turbulent region. Simulations of the equatorial 1990 GWS (planetographic latitude +12º-+5º, zonal velocity of the source 365-400 m s-1) show a different behavior because of the intense eastward jet, meridional shear at the equatorial region, and low latitude dynamics. A round shaped source forms as observed, with the rapid growth of a Kelvin-Helmholtz instability on the north side of the source due to advection and to the strong meridional wind shear, whereas at the storm latitude the disturbance grows and propagates eastward. The storm nucleus is the manifestation of a Rossby wave, while the eastward propagating planetary-scale disturbance is a gravity-Rossby wave trapped around the equator

  20. Cosmology with the WFIRST High Latitude Survey

    NASA Astrophysics Data System (ADS)

    Dore, Olivier

    Cosmic acceleration is the most surprising cosmological discovery in many decades. Testing and distinguishing among possible explanations requires cosmological measurements of extremely high precision that probe the full history of cosmic expansion and structure growth. The WFIRST-AFTA mission, as described in the Science Definition Team (SDT) reports (Spergel 2013, 2015), has the ability to improve these measurements by 1-2 orders of magnitude compared to the current state of the art, while simultaneously extending their redshift grasp, greatly improving control of systematic effects, and taking a unified approach to multiple probes that provide complementary physical information and cross-checks of cosmological results. We have assembled a team with the expertise and commitment needed to address the stringent challenges of the WFIRST dark energy program through the Project's formulation phase. After careful consideration, we have elected to address investigations A (Galaxy Redshift Survey) and C (Weak Lensing and Cluster Growth) of the WFIRST SIT NRA with a unified team, because the two investigations are tightly linked at both the technical level and the theoretical modeling level. The imaging and spectroscopic elements of the High Latitude Survey (HLS) will be realized as an integrated observing program, and they jointly impose requirements on instrument and telescope performance, operations, and data transfer. The methods for simulating and interpreting weak lensing and galaxy clustering observations largely overlap, and many members of our team have expertise in both areas. The team PI, Olivier Dore, is a cosmologist with a broad expertise in cosmic microwave background and large scale structures. Yun Wang and Chris Hirata will serve as Lead Co-Investigators for topics A and C, respectively. Many members of our team have been involved with the design and requirements of a dark energy space mission for a decade or more, including the Co-Chair and three

  1. Geographic control of Titan's mid-latitude clouds.

    PubMed

    Roe, Henry G; Brown, Michael E; Schaller, Emily L; Bouchez, Antonin H; Trujillo, Chadwick A

    2005-10-21

    Observations of Titan's mid-latitude clouds from the W. M. Keck and Gemini Observatories show that they cluster near 350 degrees W longitude, 40 degrees S latitude. These clouds cannot be explained by a seasonal shift in global circulation and thus presumably reflect a mechanism on Titan such as geysering or cryovolcanism in this region. The rate of volatile release necessary to trigger cloud formation could easily supply enough methane to balance the loss to photolysis in the upper atmosphere.

  2. Dependence of the charge exchange lifetimes on mirror latitude

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.

    1976-01-01

    The dependence of the charge exchange lifetimes on the mirror latitude for ions mirroring off the geomagnetic equator was re-computed using the improved hydrogen distribution models. The Chamberlain model was used to define the spatial distribution of the neutral hydrogen environment through which the ring current ions traverse. The resultant dependence of the charge exchange lifetime on mirror latitude is best fitted by the approximation that contains the charge exchange lifetime for equatorial particles.

  3. Polar and high latitude substorms and solar wind conditions

    NASA Astrophysics Data System (ADS)

    Despirak, I. V.; Lyubchich, A. A.; Kleimenova, N. G.

    2014-09-01

    All substorm disturbances observed in polar latitudes can be divided into two types: polar, which are observable at geomagnetic latitudes higher than 70° in the absence of substorms below 70°, and high latitude substorms, which travel from auroral (<70°) to polar (>70°) geomagnetic latitudes. The aim of this study is to compare conditions in the IMF and solar wind, under which these two types of substorms are observable on the basis of data from meridional chain of magnetometers IMAGE and OMNI database for 1995, 2000, and 2006-2011. In total, 105 polar and 55 high latitude substorms were studied. It is shown that polar substorms are observable at a low velocity of solar wind after propagation of a high-speed recurrent stream during the late recovery phase of a magnetic storm. High latitude substorms, in contrast, are observable with a high velocity of solar wind, increased values of the Bz component of the IMF, the Ey component of the electric field, and solar wind temperature and pressure, when a high-speed recurrent stream passes by the Earth.

  4. Very low latitude (L = 1.08) whistlers

    NASA Astrophysics Data System (ADS)

    Singh, Rajesh; Cohen, Morris B.; Maurya, Ajeet K.; Veenadhari, B.; Kumar, Sushil; Pant, P.; Said, Ryan K.; Inan, Umran S.

    2012-12-01

    For decades, whistlers observed on the ground at mid and high latitudes have been used for diagnostics of Earth's plasmasphere. Whistlers have also been observed at low latitudes however, the propagation characteristics of low latitude whistlers are poorly understood thus they have not been used effectively as a diagnostic for the low latitude ionosphere. One key limitation with past studies has been lack of knowledge of the whistler source lightning location. Here we present the first cases of low latitude ground whistlers most likely linked with their causative lightning discharges in the conjugate zone. The Global Lightning Dataset 360 (GLD360) detected lightning discharges were found to be located close to the conjugate location of the recording stations, providing direct evidence of inter-hemispheric propagation at the low latitudes. A total of 864 whistlers were observed at Allahabad, India (Geomag. lat. 16.05°N Geomag. long. 155.34°E L = 1.08) during the night of 26 January 2011. Using GLD360 network data, we show the occurrence of thunderstorm activity between 200 and 450 km from the conjugate point of Allahabad. We also report the distribution of peak currents of whistler-producing lightning, which demonstrate a cutoff at 30 kA.

  5. 77 FR 10800 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel ALTERNATE LATITUDE...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... LATITUDE; Invitation for Public Comments AGENCY: Maritime Administration, Department of Transportation... applicant the intended service of the vessel ALTERNATE LATITUDE is: Intended Commercial Use of...

  6. High-latitude dust in the Earth system

    NASA Astrophysics Data System (ADS)

    Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gassó, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; McKenna-Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

    2016-06-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 km2 and contribute at least 80-100 Tg yr-1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

  7. Space weather and myocardial infarction diseases at subauroral latitudes

    NASA Astrophysics Data System (ADS)

    Samsonov, Sergey; Kleimenova, Natalia; Petrova, Palmira

    The relationship of the number of calls for the emergency medical care in Yakutsk (subauroral latitudes) in connection with myocardial infarction diseases during years near the maximum (1992) and minimum (1998) of the 11-year geomagnetic disturbance cycle to space weather parameters has been studied. It is found that at subauroral latitudes, the increase of geomagnetic activity, namely, the occurrence of night magnetospheric substorms, plays the important role in the exacerbation of myocardial infarctions. Substorms are accompanied by Pi1 irregular geomagnetic pulsations with periods of (0.5-3.0) Hz, coinciding with heart rhythms of a human being, thus, these waves can be a biotropic factor negatively influencing on the occurrence of myocardial infarctions. The comparison of seasonal change of the number of calls for emergency medical care to patients at subauroral latitudes with a simultaneous seasonal change of fatal endings because of an infarction at low latitudes (Bulgaria) has shown their essential difference. Thus, in Bulgaria the maximum of infarctions have been marked in winter, and minimum - in summer, and in Yakutsk a few maxima coinciding with the sharp and considerable increases of the level of the planetary geomagnetic disturbances have been observed. In this case, in Bulgaria the infarctions could be connected with availability of the Pc1 geomagnetic pulsations. Thus, the stable quasi-sinusoidal Pc1 pulsations can be a biotropic factor influencing on the development of myocardial infarctions at middle latitudes and the Pi1 irregular geomagnetic pulsations, which do not propagate to the lower latitudes, could be a biotropic factor at subauroral latitudes.

  8. Storm time plasma transport at middle and high latitudes

    SciTech Connect

    Foster, J.C. )

    1993-02-01

    Associated with the large-scale enhancement of the ionospheric convection electric field during disturbed geomagnetic conditions, solar-produced F region plasma is transported to and through the noontime cleft from a source region at middle and low latitudes in the afternoon sector. As a result of the offset between the geomagnetic and geographic poles, the afternoon sector region of strong sunward convection is shifted to increasingly lower geographic latitude throughout the interval between 12 UT and 24 UT. A snowplow effect occurs in which the convection cell continually encounters fresh corotating ionospheric plasma along its equatorward edge, producing a latitudinally narrow region of storm-enhanced plasma density (SED) and increased total electron content which is advected toward higher latitudes in the noon sector. The Millstone Hill incoherent scatter radar regularly observes SED as a spatially continuous, large-scale feature spanning local times between noon and midnight and at latitudes between the polar cap and its mid- or low-latitude source region. For local times away from noon, the latitude of most probable SED occurrence moves equatorward by 6[degrees] for an increase of 2 in the Kp index. During strong disturbances the topside SED is observed to be convecting sunward at [approximately]750 m s[sup [minus]1] with a flux of 10[sup 14] m[sup [minus]2] s[sup [minus]1]. This feature accounts for the pronounced enhancement of ionospheric density near dusk at middle latitudes observed during the early stages of magnetic storms (called the dusk effect) and constitutes a source for the enhanced F region plasma observed in the polar cap during disturbed conditions. 34 refs., 13 figs., 1 tab.

  9. High-latitude dust in the Earth system

    USGS Publications Warehouse

    Bullard, Joanna E; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; NcKenna Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

    2016-01-01

    Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 km2 and contribute at least 80–100 Tg yr−1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

  10. Map of Martian Thorium at Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element thorium. Thorium is a naturally radioactive element that exists in rocks and soils in extremely small amounts. The region of highest thorium content, shown in red, is found in the northern part of Acidalia Planitia (50 degrees latitude, -30 degrees longitude). Areas of low thorium content, shown in blue, are spread widely across the planet with significant low abundances located to the north of Olympus Mons (near 55 degrees latitude, -155 degrees longitude), to the east of the Tharsis volcanoes (-10 degrees latitude, -80 degrees longitude) and to the south and east of Elysium Mons (20 degrees latitude, 160 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the 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.

  11. Solar correlates of Southern Hemisphere mid-latitude climate variability

    NASA Astrophysics Data System (ADS)

    Thresher, Ronald E.

    2002-06-01

    Atmospheric circulation in the southern mid-latitudes is dominated by strong circum-Antarctic zonal west winds (ZWW) over the latitude range of 35 to 60°S. These winds exhibit coherent seasonal and interannual variability, which has been related both to Antarctic (e.g. polar ice) and low-latitude climate (e.g. El Niño-southern oscillation) parameters. Historical and recent studies suggest that, at its northern margins, variability in the ZWW also has a marked quasi-decadal component. Analysis of sea-level pressure and rainfall data for the Australian region, South Africa and South America confirms frequent indications of quasi-decadal variability in parameters associated with the ZWW, which appears to be in phase around the hemisphere. This variation broadly correlates with the sunspot cycle, and specifically appears to reflect sunspot-correlated, seasonally modulated shifts in the latitude range each year of the sub-tropical ridge over eastern Australia. Sunspot-correlated variability in the southern mid-latitudes is likely to have substantial effects on temperate climate and ecology and is consistent with recent models of solar effects on upper atmospheric climate, though the mechanisms that link these to winds and rainfall at sea level remain obscure.

  12. High-latitude upgrade to the Wideband ionospheric scintillation model

    NASA Astrophysics Data System (ADS)

    Secan, J. A.; Bussey, R. M.; Fremouw, E. J.; Basu, S.

    1997-07-01

    The high-latitude sections of the Wideband ionospheric scintillation model (WBMOD) have been upgraded extensively, based on analysis of scintillation data from the Defense Nuclear Agency Wideband, HiLat, and Polar BEAR satellite-beacon experiments. Data collected at Sondre Stromfjord, Greenland; Tromso, Norway; Fort Churchill, Canada; and Bellevue, Washington (United States) over a 4-year period were analyzed, and the results of these analyses were used to construct a completely new model for the behavior of the height-integrated irregularity-strength parameter (CkL) at high latitudes. The new high-latitude CkL model includes variations with sunspot number, geomagnetic activity (Kp), latitude, local time, longitude, and season. The new WBMOD CkL models (equatorial and high-latitude) have been implemented in a more versatile code, denoted SCINTMOD, which has the capability to generate a wide range of user-controlled maps of scintillation effects over large spatial areas. Examples of the types of graphical output that SCINTMOD can generate are presented.

  13. Spectral losses of high concentrator photovoltaic modules depending on latitude

    NASA Astrophysics Data System (ADS)

    Soria-Moya, Alberto; Fernández, Eduardo F.; Almonacid, Florencia; Mallick, Tapas K.

    2015-09-01

    High concentrator photovoltaic (HCPV) modules and systems are affected by changes on the incident solar spectrum. It is well known that among all the atmospheric parameters, the air mass has the largest impact on the spectral behavior of HCPV devices. The air mass can be considered as a geometrical parameter which depends entirely on the Sun's zenith angle (θ). Because of this, the yield of HCPV modules is affected by latitude. In this paper, a new method to estimate the gains/losses of energy due to the spectral impact has been introduced. Furthermore, the annual spectral losses depending on latitude have been calculated for several theoretical modules. For default values defined in the standard AM1.5d ASTM G-173-03 spectrum, results show that the spectral losses are almost independent of latitude for locations with low latitude values. Losses between 3% and 5% on the annual energy yield have been estimated for those areas. For high latitudes, the losses increase until they reach values between 10% and 14%. Results depend on the multi-junction solar cells and optical devices of the HCPV module considered.

  14. Map of Martian Thorium at Mid-Latitudes

    NASA Image and Video Library

    2003-03-13

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element thorium. Thorium is a naturally radioactive element that exists in rocks and soils in extremely small amounts. The region of highest thorium content, shown in red, is found in the northern part of Acidalia Planitia (50 degrees latitude, -30 degrees longitude). Areas of low thorium content, shown in blue, are spread widely across the planet with significant low abundances located to the north of Olympus Mons (near 55 degrees latitude, -155 degrees longitude), to the east of the Tharsis volcanoes (-10 degrees latitude, -80 degrees longitude) and to the south and east of Elysium Mons (20 degrees latitude, 160 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south. http://photojournal.jpl.nasa.gov/catalog/PIA04257

  15. AN ABSENCE OF FAST RADIO BURSTS AT INTERMEDIATE GALACTIC LATITUDES

    SciTech Connect

    Petroff, E.; Van Straten, W.; Bailes, M.; Barr, E. D.; Coster, P.; Flynn, C.; Keane, E. F.; Johnston, S.; Bates, S. D.; Keith, M. J.; Kramer, M.; Stappers, B. W.; Bhat, N. D. R.; Burgay, M.; Possenti, A.; Tiburzi, C.; Burke-Spolaor, S.; Champion, D.; Ng, C.; Levin, L.; and others

    2014-07-10

    Fast radio bursts (FRBs) are an emerging class of bright, highly dispersed radio pulses. Recent work by Thornton et al. has revealed a population of FRBs in the High Time Resolution Universe (HTRU) survey at high Galactic latitudes. A variety of progenitors have been proposed, including cataclysmic events at cosmological distances, Galactic flare stars, and terrestrial radio frequency interference. Here we report on a search for FRBs at intermediate Galactic latitudes (–15° latitudes. A revised rate estimate or another strong and heretofore unknown selection effect in Galactic latitude would provide closer agreement between the surveys' detection rates. The dearth of detections at low Galactic latitude disfavors a Galactic origin for these bursts.

  16. Impact of Wetlands on Titan's Mid-Latitude Cloudiness

    NASA Astrophysics Data System (ADS)

    Lora, J. M.; Mitchell, J.

    2014-12-01

    Neish and Lorenz [Icarus 228 (2014), 27-34] suggested that Titan's lowest elevations are extensive wetlands based on crater distributions. With a Titan general circulation model (GCM), we examine whether low-lying wetlands at mid-latitudes provide sufficient surface-level moisture to trigger convective cloud formation there, as well as investigate the dynamical processes responsible for different cloud morphologies. GCMs of Titan have shown that the atmospheric circulation transports methane away from low latitudes and into the polar regions on average. Several of these models simulate moist and cloudy conditions over the summer pole, in agreement with observations of convective clouds over the south pole during its summer. However, observations of cloudiness over Titan's southern mid-latitudes that occurred around solstice and persisted until after autumnal equinox are perplexing. GCMs tend to only simulate mid-latitude clouds around equinox, and only when imposing very wet surface conditions. In GCMs where surface moisture is allowed to vary self-consistently, the mid-latitudes are dry and cloud formation is inhibited. However, these models ignore topography. The GCM in this study is three-dimensional and fully simulates Titan's methane cycle, including variable surface moisture, as well as Titan's temperatures and atmospheric superrotation. Comparison of model results to recent obsrvations of the latitudinal humidity distribution of the troposphere will help discriminate between surface distributions. These simulations can therefore begin to constrain the distribution of surface methane, beyond Titan's distinctive lakes and seas, available to the atmosphere.

  17. Global analysis of thermal tolerance and latitude in ectotherms.

    PubMed

    Sunday, Jennifer M; Bates, Amanda E; Dulvy, Nicholas K

    2011-06-22

    A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean.

  18. Global analysis of thermal tolerance and latitude in ectotherms

    PubMed Central

    Sunday, Jennifer M.; Bates, Amanda E.; Dulvy, Nicholas K.

    2011-01-01

    A tenet of macroecology is that physiological processes of organisms are linked to large-scale geographical patterns in environmental conditions. Species at higher latitudes experience greater seasonal temperature variation and are consequently predicted to withstand greater temperature extremes. We tested for relationships between breadths of thermal tolerance in ectothermic animals and the latitude of specimen location using all available data, while accounting for habitat, hemisphere, methodological differences and taxonomic affinity. We found that thermal tolerance breadths generally increase with latitude, and do so at a greater rate in the Northern Hemisphere. In terrestrial ectotherms, upper thermal limits vary little while lower thermal limits decrease with latitude. By contrast, marine species display a coherent poleward decrease in both upper and lower thermal limits. Our findings provide comprehensive global support for hypotheses generated from studies at smaller taxonomic subsets and geographical scales. Our results further indicate differences between terrestrial and marine ectotherms in how thermal physiology varies with latitude that may relate to the degree of temperature variability experienced on land and in the ocean. PMID:21106582

  19. Map of Martian Thorium at Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element thorium. Thorium is a naturally radioactive element that exists in rocks and soils in extremely small amounts. The region of highest thorium content, shown in red, is found in the northern part of Acidalia Planitia (50 degrees latitude, -30 degrees longitude). Areas of low thorium content, shown in blue, are spread widely across the planet with significant low abundances located to the north of Olympus Mons (near 55 degrees latitude, -155 degrees longitude), to the east of the Tharsis volcanoes (-10 degrees latitude, -80 degrees longitude) and to the south and east of Elysium Mons (20 degrees latitude, 160 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the 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.

  20. CORAL REEFS. Genomic determinants of coral heat tolerance across latitudes.

    PubMed

    Dixon, Groves B; Davies, Sarah W; Aglyamova, Galina A; Meyer, Eli; Bay, Line K; Matz, Mikhail V

    2015-06-26

    As global warming continues, reef-building corals could avoid local population declines through "genetic rescue" involving exchange of heat-tolerant genotypes across latitudes, but only if latitudinal variation in thermal tolerance is heritable. Here, we show an up-to-10-fold increase in odds of survival of coral larvae under heat stress when their parents come from a warmer lower-latitude location. Elevated thermal tolerance was associated with heritable differences in expression of oxidative, extracellular, transport, and mitochondrial functions that indicated a lack of prior stress. Moreover, two genomic regions strongly responded to selection for thermal tolerance in interlatitudinal crosses. These results demonstrate that variation in coral thermal tolerance across latitudes has a strong genetic basis and could serve as raw material for natural selection.

  1. Theory of the low-latitude boundary layer

    NASA Technical Reports Server (NTRS)

    Sonnerup, B. U. OE.

    1980-01-01

    A one-dimensional steady state fluid mechanical model is developed of the low-latitude plasma boundary layer inside the dawn and dusk magnetopause. Momentum transfer in the layer is produced by viscosity and/or mass diffusion. Coupling to the ionosphere is achieved via field-aligned currents, the magnitude of which is limited by parallel potential drops. These currents flow into and out of the ionosphere in the manner described by Iijima and Potemra. The higher-latitude (region 1) currents are associated with the boundary layer proper, while the lower-latitude (region 2) ones are associated with a region of sunward return flow adjacent to the boundary layer. The parallel potential drops have a magnitude of typically 2-3 kV and a north-south extent of 100-200 km. The calculated potential profile corresponds reasonably well to observed inverted V precipitation events.

  2. Star Formation in High-Latitude Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Magnus McGehee, Peregrine

    2015-08-01

    Galactic star formation preferentially occurs within the dense molecular clouds that reside primarily near the disk mid-plane and are thus seen in projection against the Milky Way. A population of molecular clouds are seen at higher Galactic latitude although distance determinations are required in order to identify those that are actually in extraplanar environments.We review the known high-latitude star formation regions (MBM 12, LDN 1642, and HRK 81.4-77.8) and discuss the nature and environment of other high-latitude molecular clouds. Distances to each of these structures are deduced from optical reddening profiles derived from analysis of Sloan Digital Sky Survey photometry. In particular, we examine those molecular clouds found within the complex of intermediate and high velocity HI clouds that span the Northern 2nd Galactic Quadrant: the Draco clouds, the IVC pair at (l+b) = 135+51 and 135+54, and IREC 306.

  3. On the Origins of the High-latitude Hα Background

    NASA Astrophysics Data System (ADS)

    Witt, Adolf N.; Gold, Benjamin; Barnes, Frank S., III; DeRoo, Casey T.; Vijh, Uma P.; Madsen, Gregory J.

    2010-12-01

    The diffuse high-latitude Hα background is widely believed to be predominantly the result of in situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude Hα intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude Hα background are the result of scattering by interstellar dust of Hα photons originating elsewhere in the Galaxy. We provide an empirical relation, which relates the expected scattered Hα intensity to the IRAS 100 μm diffuse background intensity, applicable to about 81% of the entire sky. The assumption commonly made in reductions of cosmic microwave background observations, namely that the observed all-sky map of diffuse Hα light is a suitable template for Galactic free-free foreground emission, is found to be in need of reexamination.

  4. Operational high latitude surface irradiance products from polar orbiting satellites

    NASA Astrophysics Data System (ADS)

    Godøy, Øystein

    2016-12-01

    It remains a challenge to find an adequate approach for operational estimation of surface incoming short- and longwave irradiance at high latitudes using polar orbiting meteorological satellite data. In this presentation validation results at a number of North Atlantic and Arctic Ocean high latitude stations are presented and discussed. The validation results have revealed that although the method works well and normally fulfil the operational requirements, there is room for improvement. A number of issues that can improve the estimates at high latitudes have been identified. These improvements are partly related to improved cloud classification using satellite data and partly related to improved handling of multiple reflections over bright surfaces (snow and sea ice), especially in broken cloud conditions. Furthermore, the availability of validation sites over open ocean and sea ice is a challenge.

  5. Magnetic Field Elements at High Latitude: Lifetime and Rotation Rate

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Zhao, J.

    2009-12-01

    Using one-minute cadence time-series full disk magnetograms taken by the SOHO/MDI, we have studied the magnetic field elements at high latitude (poleward of 65° in latitude). It is found that an average lifetime of the magnetic field elements is 16.5 h during solar minimum, much longer than that during solar maximum (7.3 h). During solar minimum, number of the magnetic field elements with the dominant polarity is about 3 times as that of the opposite polarity elements. Their lifetime is 21.0 h on average, longer than that of the opposite polarity elements (2.3 h). It is also found that the lifetime of the magnetic field elements is related with their size, consistent with the magnetic field elements in the quiet sun at low latitude found by Hagenaar et al. ( Astrophys. J. 511:932, 1999). During solar maximum, the polar regions are equally occupied by magnetic field elements with both polarities, and their lifetimes are roughly the same on average. No evidence shows there is a correlation between the lifetime and size of the magnetic field elements. Using an image cross-correlation method, we also measure the solar rotation rate at high latitude, up to 85° in latitude. The rate is ω=2.914-0.342sin 2 φ-0.482sin 4 φ μrad s-1 sidereal. It agrees with previous studies using the spectroscopic and image cross-correlation methods, and also agrees with the results using the element tracking method when the sample of the tracked magnetic field elements is large. The consistency of those results strongly suggests that this rate at high latitude is reliable.

  6. THEORY OF SOLAR MERIDIONAL CIRCULATION AT HIGH LATITUDES

    SciTech Connect

    Dikpati, Mausumi; Gilman, Peter A. E-mail: gilman@ucar.edu

    2012-02-10

    We build a hydrodynamic model for computing and understanding the Sun's large-scale high-latitude flows, including Coriolis forces, turbulent diffusion of momentum, and gyroscopic pumping. Side boundaries of the spherical 'polar cap', our computational domain, are located at latitudes {>=} 60 Degree-Sign . Implementing observed low-latitude flows as side boundary conditions, we solve the flow equations for a Cartesian analog of the polar cap. The key parameter that determines whether there are nodes in the high-latitude meridional flow is {epsilon} = 2{Omega}n{pi}H{sup 2}/{nu}, where {Omega} is the interior rotation rate, n is the radial wavenumber of the meridional flow, H is the depth of the convection zone, and {nu} is the turbulent viscosity. The smaller the {epsilon} (larger turbulent viscosity), the fewer the number of nodes in high latitudes. For all latitudes within the polar cap, we find three nodes for {nu} = 10{sup 12} cm{sup 2} s{sup -1}, two for 10{sup 13}, and one or none for 10{sup 15} or higher. For {nu} near 10{sup 14} our model exhibits 'node merging': as the meridional flow speed is increased, two nodes cancel each other, leaving no nodes. On the other hand, for fixed flow speed at the boundary, as {nu} is increased the poleward-most node migrates to the pole and disappears, ultimately for high enough {nu} leaving no nodes. These results suggest that primary poleward surface meridional flow can extend from 60 Degree-Sign to the pole either by node merging or by node migration and disappearance.

  7. Understanding the Relation between Attitude Involvement and Response Latitude Using Item Response Theory

    ERIC Educational Resources Information Center

    Lake, Christopher J.; Withrow, Scott; Zickar, Michael J.; Wood, Nicole L.; Dalal, Dev K.; Bochinski, Joseph

    2013-01-01

    Adapting the original latitude of acceptance concept to Likert-type surveys, response latitudes are defined as the range of graded response options a person is willing to endorse. Response latitudes were expected to relate to attitude involvement such that high involvement was linked to narrow latitudes (the result of selective, careful…

  8. Understanding the Relation between Attitude Involvement and Response Latitude Using Item Response Theory

    ERIC Educational Resources Information Center

    Lake, Christopher J.; Withrow, Scott; Zickar, Michael J.; Wood, Nicole L.; Dalal, Dev K.; Bochinski, Joseph

    2013-01-01

    Adapting the original latitude of acceptance concept to Likert-type surveys, response latitudes are defined as the range of graded response options a person is willing to endorse. Response latitudes were expected to relate to attitude involvement such that high involvement was linked to narrow latitudes (the result of selective, careful…

  9. Effect of high latitude filtering on NWP skill

    NASA Technical Reports Server (NTRS)

    Kalnay, E.; Hoffman, R.; Takacs, L. L.

    1983-01-01

    An assessment is made of the extent to which polar filtering may seriously affect the skill of latitude-longitude NWP models, such as the U.S. Navy's NOGAPS, or the GLAS fourth-order model. The limited experiments which have been completed to date with the 4 x 5-deg, 9-level version of the latter model indicate that the high latitude filter currently in operation affects its forecasting skill very little, with only one exception in which the use of the PG filter significantly improved forecasting.

  10. Deriving a Latitude-Optimized Pyranometer Calibration Factor: Preprint

    SciTech Connect

    Wilcox, S. M.; Myers, D. R.; Reda, I. M. A.

    2002-03-01

    Work in recent years has produced improvements in determining the solar resource by better characterizing the responsivity of pyranometers. The calibration process can characterize a common responsivity dependency on the solar zenith angle, which can then be used to compensate for sensor variations during instrument deployment. However, daily compensation throughout the range of zenith angles might not be necessary for applications requiring only annual irradiance. This paper describes a method of identifying a measurement bias due to latitude of deployment and optimizing an instrument's clear-sky responsivity for annual solar radiation measurements based on the relationship between solar zenith angles and the latitude.

  11. Energy sources of the high latitude upper atmosphere

    NASA Technical Reports Server (NTRS)

    Banks, P. M.

    1981-01-01

    Electrodynamic (Joule) dissipation and plasma wave heating are reviewed as sources of energy for the upper atmosphere at high latitudes. Electrodynamic heating in the thermosphere is described by a generalized energy balance equation taking into account a variety of inelastic processes and energy losses, and the use of height-integrated values of the Joule heating rate to estimate the importance of electrodynamic heating at high latitudes is discussed. Observations of electrons between 95 and 115 km altitude that are up to 1000 K hotter than the neutral atmosphere is presented as evidence for atmospheric heating due to unstable plasma waves arising from the Farley-Buneman modified two-stream instability.

  12. Radio-Wave Scintillations and Ionospheric Irregularities at High Latitudes.

    DTIC Science & Technology

    1987-05-30

    Pryse N. S. Wheadon University College of Wales Department of Physics Aberystwyth, United Kingdom 30 May 1987 Final Report 1 April 1986 - 31 March...irreaularities at hizh latitud s 12. PERSONAL AUTHORS) L. Kersley, S. E. Pryse and 14. S. Wheadon 13& TYPE OF REPORT 13b. TIME COVERED 14D ATE OF REPORT (Yr...latitude F-region irregularities. 3. Geophys. Res., 87, 4469, 1982. 6. Kersley L., Pryse S.E. and Vheadon N.S. Radiowave scintillations and ionospheric

  13. Comparison of IRI model predictions with low latitude ionospheric observations

    NASA Astrophysics Data System (ADS)

    Bittencourt, J. A.; Chryssafidis, M.

    During a period of high solar activity (1979/1980), IRI-predicted electron density profiles were compared with measurements made at Fortaleza (Brazil), 2 degrees off the dip equator. A few discrepancies were found. They are attributed mainly to dynamical effects associated with low latitude E x B electromagnetic plasma drifts and thermospheric neutral winds that are not correctly reproduced in the CCIR numerical maps and in the IRI profile shapes as well. In particular, the dependence on the magnetic declination angle, which strongly affects the electrodynamical plasma motions at low latitudes, is not satisfactorily considered in the models.

  14. Equivalent Latitude Computation Using Regions of Interest (ROI)

    PubMed Central

    Añel, Juan A.; Allen, Douglas R.; Sáenz, Guadalupe; Gimeno, Luis; de la Torre, Laura

    2013-01-01

    This paper introduces a novel algorithm to compute equivalent latitude by applying regions of interest (ROI). The technique is illustrated using code written in Interactive Data Language (IDL). The ROI method is compared with the “piecewise-constant” method, the approach commonly used in atmospheric sciences, using global fields of atmospheric potential vorticity. The ROI method is considerably more accurate and computationally faster than the piecewise-constant method, and it also works well with irregular grids. Both the ROI and piecewise-constant IDL codes for equivalent latitude are included as a useful reference for the research community. PMID:24086267

  15. High latitude regulation of low latitude thermocline ventilation and planktic foraminifer populations across glacial-interglacial cycles

    NASA Astrophysics Data System (ADS)

    Sexton, Philip F.; Norris, Richard D.

    2011-11-01

    One of the earliest discoveries in palaeoceanography was the observation in 1935 that the (sub)tropical planktic foraminifer Globorotalia menardii became absent or extremely rare in the Atlantic Ocean during glacials of the late Pleistocene. Yet a mechanistic explanation for G. menardii's extraordinary biogeographic behaviour has eluded palaeoceanographers for 75 years. Here we show that modern G. menardii, along with two other species that also suffer Atlantic population collapses during glacials, track poorly ventilated waters globally in their thermocline habitats. The ventilation states of low latitude thermoclines are 'set', to a first order, by intermediate water masses originating at high latitudes. In the modern Atlantic this control on low latitude thermocline ventilation is exerted by relatively poorly ventilated, southern-sourced Antarctic Intermediate Water (AAIW) and sub-Antarctic Mode Water (SAMW). We suggest that the glacial Atlantic foraminifer population collapses were a consequence of a low latitude thermocline that was better ventilated during glacials than it is today, in line with geochemical evidence, and driven primarily by a well-ventilated, northern-sourced intermediate water mass. A ventilation mechanism driving the glacial population collapses is further supported by our new constraints on the precise timing of these species' Atlantic proliferation during the last deglaciation — occurring in parallel with a wholesale, bipolar reorganisation of the Atlantic's thermocline-to-abyssal overturning circulation. Our findings demonstrate that a bipolar seesaw in the formation of high latitude intermediate waters has played an important role in regulating the population dynamics of thermocline-dwelling plankton at lower latitudes.

  16. Lateral ventricle morphology analysis via mean latitude axis.

    PubMed

    Paniagua, Beatriz; Lyall, Amanda; Berger, Jean-Baptiste; Vachet, Clement; Hamer, Robert M; Woolson, Sandra; Lin, Weili; Gilmore, John; Styner, Martin

    2013-03-29

    Statistical shape analysis has emerged as an insightful method for evaluating brain structures in neuroimaging studies, however most shape frameworks are surface based and thus directly depend on the quality of surface alignment. In contrast, medial descriptions employ thickness information as alignment-independent shape metric. We propose a joint framework that computes local medial thickness information via a mean latitude axis from the well-known spherical harmonic (SPHARM-PDM) shape framework. In this work, we applied SPHARM derived medial representations to the morphological analysis of lateral ventricles in neonates. Mild ventriculomegaly (MVM) subjects are compared to healthy controls to highlight the potential of the methodology. Lateral ventricles were obtained from MRI scans of neonates (9-144 days of age) from 30 MVM subjects as well as age- and sex-matched normal controls (60 total). SPHARM-PDM shape analysis was extended to compute a mean latitude axis directly from the spherical parameterization. Local thickness and area was straightforwardly determined. MVM and healthy controls were compared using local MANOVA and compared with the traditional SPHARM-PDM analysis. Both surface and mean latitude axis findings differentiate successfully MVM and healthy lateral ventricle morphology. Lateral ventricles in MVM neonates show enlarged shapes in tail and head. Mean latitude axis is able to find significant differences all along the lateral ventricle shape, demonstrating that local thickness analysis provides significant insight over traditional SPHARM-PDM. This study is the first to precisely quantify 3D lateral ventricle morphology in MVM neonates using shape analysis.

  17. Redefining the Longitude/Latitude Experience with a Scaffolded Geocache

    ERIC Educational Resources Information Center

    Hammond, Thomas; Bozdin, Alec M.; Stanlick, Sarah E.

    2014-01-01

    Latitude and longitude are foundational concepts for geography education, yet they are typically poorly understood by students and receive indifferent attention from instructors and publishers' materials. Social studies teachers can take advantage of increasingly ubiquitous geolocating devices such as Global Positions Systems (GPS) to provide…

  18. Chandra Bulge Latitude Survey (BLS): Overview and Source Distributions

    NASA Astrophysics Data System (ADS)

    Grindlay, Jonathan E.; Hong, J.; Van den Berg, M.; Servillat, M.; Zhao, P.

    2010-03-01

    The Chandra Bulge Latitude Survey (BLS) is mosaic of some 36 Chandra pointings with ACIS-I covering approximately 3 degrees in latitude and 1 degree in longitude and centered on the Galactic Center. We proposed this (Chandra Cycle 7) to complement the Chandra survey of the Galactic Center Region conducted by Wang et al (2002) which surveyed a similar region but aligned in longitude along the galactic plane. The combination of these two surveys would then give the complete latitude vs. longitude distributions of the sources in the central Bulge of the Galaxy. We have completed the survey and present here the full mosaic image of the BLS to study the latitude distribution, in particular, of the Bulge sources. With integration times of 15ksec per ACIS-I field, and with the full Chandra band used, the BLS reaches fainter limiting fluxes than the Wang Survey. In combination with wide-field optical (CTIO-mosaic) imaging and followup Hydra spectroscopy(see poster by Zhao et al) and IR imaging (CTIO-ISPI) in JHK (see poster by van den Berg et al), we have mapped the source distribution and content. In this talk we present the global results and comparisons with source populations in the central Bulge.

  19. Map of Martian Iron at Mid-Latitudes

    NASA Image and Video Library

    2003-03-13

    This gamma ray spectrometer map from NASA Mars Odyssey of the mid-latitude region of Mars is based on gamma-rays from the element iron, one of the most abundant elements on Mars and Earth. It is responsible for the red color on the surface of Mars.

  20. Teaching Latitude and Longitude in the Upper Elementary Grades.

    ERIC Educational Resources Information Center

    Johnson, Peter C.; Gondesen, Mark E.

    1991-01-01

    Discusses the desirability of teaching latitude and longitude concepts to upper elementary students. Includes a four-lesson unit on the topics. Employs hurricane tracking information available from the National Hurricane Center. Provides a foundation for future lessons on Middle and North American geography. (SG)

  1. Earth-Sun Relationships: Latitude, Longitude and Time.

    ERIC Educational Resources Information Center

    Thomas, Paul F.

    High school students learn about the sun's effects on the earth by examining the concepts of latitude and longitude, seasons, and time. Each of these topics is treated in a separate, but similarly organized, unit. Relevant vocabulary is introduced, and complex terms are clarified with diagrams and illustrations. In the unit on time, potentially…

  2. Map of Martian Silicon at Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element silicon. Silicon is one of the most abundant elements on the surface of both Mars and Earth (second only to oxygen). The most extensive region of highest silicon content, shown in red, is located in the high latitudes north of Tharsis (centered near 45 degrees latitude, -120 degrees longitude). The area of lowest silicon content, shown in blue, lies just to the east of the Hellas Basin (-45 degrees latitude, 90 degrees longitude). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the 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.

  3. The yield advantages of artificial regeneration at high latitudes.

    Treesearch

    M. Murray

    1986-01-01

    The 6th international workshop on forest regeneration at high latitudes took place during a period of transition for the forest industry worldwide. The economic slump in the forest products industry had bottomed-out; the planting approach to forest regeneration was being questioned, primarily, but not solely for economic reasons; the future of the workshops on forest...

  4. Forest regeneration at high latitudes: experience from northern Sweden.

    Treesearch

    Mayo Murray

    1981-01-01

    The problem of obtaining adequate and economical forest regeneration is of major concern among the managers of high-latitude forest lands. In 1979 forest researchers and managers from Scandinavia and North America held the first of three workshops to address this topic by sharing experiences and research from each county. The first workshop was held in Umei, Sweden in...

  5. Multifractal analysis of low-latitude geomagnetic fluctuations

    NASA Astrophysics Data System (ADS)

    Bolzan, M. J. A.; Rosa, R. R.; Sahai, Y.

    2009-02-01

    The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5° N, 69.2° W) geomagnetic fluctuations can be described from direct dissipation process or loading-unloading regimes of the solar wind-magnetosphere coupling. In this paper, we analyze the H-component of low-latitude (22.4° S, 43.6° W) geomagnetic field variability observed during the month of July 2000 at the Geomagnetic Observatory, Vassouras, RJ, Brazil. The variability pattern during this period is a mixture of quiet and disturbed days including the Bastille Day intense geomagnetic storm on 15 July. Due to the complexity of this data, we pursue a detailed analysis of the geomagnetic fluctuations in different time scales including a multifractal approach using the singular power spectrum deviations obtained from the wavelet transform modulus maxima (WTMM). The results suggest, as observed from high-latitude data, the occurrence of low-latitude multifractal processes driving the intermittent coupling between the solar wind-magnetosphere and geomagnetic field variations. On finer scales possible physical mechanisms in the context of nonlinear magnetosphere response are discussed.

  6. Simulation of nose whistlers: An application to low latitude whistlers

    NASA Astrophysics Data System (ADS)

    Singh, Kalpana; Singh, R. P.; Kumar Singh, Abhay; Singh, R. N.

    2006-05-01

    Simulation technique for whistler mode signal propagating through inhomogeneous plasma using WKB approximation has been developed (Singh, K., Singh, R.P., Ferencz, O.E., 2004. Simulation of whistler mode propagation for low latitude stations. Earth Planet Space 56, 979-987). In the present paper, we have used it for the analysis of recorded signals at low latitudes and estimated the nose frequency, which is not observed on the dynamic spectra. At low latitudes nose frequency is ˜100 kHz or more and therefore it is absent in the dynamic spectra due to attenuation of the signal at higher frequencies. The importance of nose frequency is in determining the exact path of propagation, which is required in probing of ambient medium. It is shown that the method permits to study the nose frequency variation, it can be used to deduce physical parameters as the global electric field. A case study permits to get a reasonable value of the electric field, which up to now could not be done at very low latitude.

  7. Seasonal dependence of the substorm overshielding at the subauroral latitude

    NASA Astrophysics Data System (ADS)

    Hashimoto, K. K.; Kikuchi, T.

    2012-12-01

    We have shown that the equatorial counter electrojet (CEJ) is observed on the dayside when the overshielding electric field is dominant at subauroral latitudes on the dusk during substorm expansion phase. In this study, we examine if all the equatorial CEJs are accompanied by overshielding at subauroral latitudes by using ground magnetometer networks, IMAGE and INTERMAGNET during the period from 2000 to 2003. We selected 469 CEJ events from magnetometer data at Huancayo in Peru observed with the positive bay at Kakioka, Japan on the nightside. Overshielding was observed at subauroral stations of the IMAGE for 263 CEJ events, while it was not observed for 206 events. We found that the occurrence of the overshielding at subauroral latitudes significantly depends on the season; they tend to occur in the winter period from November to February. On the other hand, the convection electric field is dominant at the subauroral latitude during the northern summer period from April to August. Overshielding electric field that causes the CEJ during the northern summer should be originated from the southern hemisphere. Our results suggest that the overshielding electric field is stronger in winter than in summer if the convection electric field does not depend on the season. These features would be explained by assuming that the dynamo for the Region-1 field-aligned currents (R1 FACs) is the voltage generator, while that for the R2 FACs is the current generator.

  8. Heliomagnetic latitude dependence of the heliospheric magnetic field

    NASA Technical Reports Server (NTRS)

    Burton, M. E.; Smith, E. J.; Balogh, A.

    1995-01-01

    Previous studies have revealed systematic variations of the interplanetary magnetic field with heliographic latitude. Luhmann et al. (1987) modeled Pioneer Venus (PVO) and ISEE-3 observations by assuming an asymmetric dependence on heliolatitude with stronger fields in the northern hemisphere. In a subsequent study, using data from ISEE-3/ICE and IMP-8, Burton et al. (1990) found evidence for a similar asymmetry. However, neither model has been completely successful. The model derived from PVO/ICE observations agrees quite well near solar maximum but shows significant discrepancies during the descending phase of the solar cycle. The model derived from the ICE/IMP-8 comparison suffers from significant phase delays between the difference in field magnitude at the two spacecraft and their latitude difference. In an attempt to account for these phase shifts, the IMP-8 and ICE data have been reexamined in heliomagnetic coordinates which are defined by the orientation of the solar magnetic dipole. The latitude and longitude of the dipole inferred from the data have then been compared with those implicit in source surface calculations. The IMP/ICE correlations have been extended into the recent solar maximum and descending phase. Comparisons have also been carried out between IMP-8 and Ulysses as it traveled to -30 deg south heliographic latitude.

  9. Programmed Latitude and Longitude, Special Publication Number 10.

    ERIC Educational Resources Information Center

    Hoover, Jean C.

    Designed to measure skills involving latitude and longitude, this is a self-administering linear program for junior-high geography students. Students progress through 59 pages of fill-in-the-blank items, accompanied by appropriate line drawings, for which the correct answers are given below each question. Following the method of programmed…

  10. Ulysses solar wind plasma observations at high latitudes

    SciTech Connect

    Riley, P.; Bame, S.J.; Barraclough, B.L.

    1996-10-01

    Ulysses reached its peak northerly heliolatitude of 80.2{degrees}N on July 31, 1995, and now is moving towards aphelion at 5.41 AU which it will reach in May, 1998. We summarize measurements from the solar wind plasma experiment, SWOOPS, emphasizing northern hemispheric observations but also providing southern and equatorial results for comparison. The solar wind momentum flux during Ulysses` fast pole-to- pole transit at solar minimum was significantly higher over the poles than at near-equatorial latitudes, suggesting a non-circular cross section for the heliosphere. Furthermore, modest asymmetries in the wind speed, density, and mass flux were observed between the two hemispheres during the fast latitude scan. The solar wind was faster and less dense in the north than in the south. These asymmetries persist in the most recent high- and mid-latitude data but are less pronounced. As of July 1, 1996 the northern fast solar wind has lacked any strong stream interactions or shocks and, although a comprehensive search has not yet been made, no CMEs have yet been identified during this interval. On the other hand, Alfv{acute e}nic, compressional, and pressure balanced features are abundant at high latitudes. The most recent data, at 4 AU and 32{degrees}N, has begun to show the effects of solar rotation modulated features in the form of recurrent compressed regions.

  11. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  12. Working Model of a Foucault Pendulum at Intermediate Latitudes

    ERIC Educational Resources Information Center

    Sears, Francis W.

    1969-01-01

    Describes a working model of a Foucault pendulum at intermediate latitudes constructed of a steel drill rod with a steel ball attached at one end. The rod makes an angle of 45 degrees with the rotation axis of a horizontal turntable. The vibrating system is the same as that which led Foucault to construct his first gravity pendulum. (LC)

  13. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  14. The Interchange Instability in High-Latitude Plasma Blobs.

    DTIC Science & Technology

    1986-12-30

    identify by block number) FIELD GROUP SUB- GROUP Ionospheric structure, Radio scintillation mechanism Interchange instability High latitude ionosphere...become important. We present Fome sImple analytical expressions for the growth rate of The E* B Instability "or the above three cases in Appendix B. It

  15. Mapping High Latitude Gravity Wave Amplitudes over Antarctica during Summer

    NASA Astrophysics Data System (ADS)

    Badenhausen, P.; Millan, R. M.; Gerrard, A. J.

    2015-12-01

    Appropriate inclusion of gravity wave amplitudes into general circulation models is required to get accurate atmospheric circulation characteristics. However, high latitude gravity wave amplitudes are particularly difficult to obtain due to the challenging experimental and logistical constraints in these regions. In this study, we present gravity wave climatology of high latitudes during austral summer conditions over the Antarctic continent. These data were obtained using high-resolution GPS measurements aboard long duration high altitude balloon flights that were flown as part of the NASA Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL) mission in December 2013-February 2014 and December 2012-February 2013. The results show increased gravity wave activity along the coast of the Antarctic continent, particularly over the Peninsula and Halley Bay, whereas at higher latitudes, particularly over regions near the South Pole, gravity wave amplitudes decrease substantially. Through use of horizontal winds data, we obtained measurements of the vertical transport of horizontal momentum fluxes, which were unusually high for the summer high latitude lower stratosphere. Such unique measurements as these are immediately applicable to understanding of upwelling in the summer middle atmosphere as well as to the formation of overlaying mesospheric clouds formation.

  16. Tropical and mid-latitude forcing of continental Antarctic temperatures

    NASA Astrophysics Data System (ADS)

    Turney, C. S. M.; Fogwill, C. J.; Klekociuk, A. R.; van Ommen, T. D.; Curran, M. A. J.; Moy, A. D.; Palmer, J. G.

    2015-12-01

    Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid-latitudes to high latitudes of the Southern Hemisphere (SH), which over the last few decades have experienced extreme and regionally variable trends in precipitation, ocean circulation and temperature, with major implications for Antarctic ice melt and surface mass balance. Unfortunately there is a relative dearth of observational data, limiting our understanding of the driving mechanism(s). Here we report a new 130-year annually resolved record of δD - a proxy for temperature - from the geographic South Pole where we find a significant influence from extratropical pressure anomalies which act as "gatekeepers" to the meridional exchange of air masses. Reanalysis of global atmospheric circulation suggests these pressure anomalies play a significant influence on mid- to high-latitude SH climate, modulated by the tropical Pacific Ocean. This work adds to a growing body of literature confirming the important roles of tropical and mid-latitude atmospheric circulation variability on Antarctic temperatures. Our findings suggest that future increasing tropical warmth will strengthen meridional circulation, exaggerating current trends, with potentially significant impacts on Antarctic surface mass balance.

  17. Earth-Sun Relationships: Latitude, Longitude and Time.

    ERIC Educational Resources Information Center

    Thomas, Paul F.

    High school students learn about the sun's effects on the earth by examining the concepts of latitude and longitude, seasons, and time. Each of these topics is treated in a separate, but similarly organized, unit. Relevant vocabulary is introduced, and complex terms are clarified with diagrams and illustrations. In the unit on time, potentially…

  18. Redefining the Longitude/Latitude Experience with a Scaffolded Geocache

    ERIC Educational Resources Information Center

    Hammond, Thomas; Bozdin, Alec M.; Stanlick, Sarah E.

    2014-01-01

    Latitude and longitude are foundational concepts for geography education, yet they are typically poorly understood by students and receive indifferent attention from instructors and publishers' materials. Social studies teachers can take advantage of increasingly ubiquitous geolocating devices such as Global Positions Systems (GPS) to provide…

  19. DNA damage profiles induced by sunlight at different latitudes.

    PubMed

    Schuch, André Passaglia; Yagura, Teiti; Makita, Kazuo; Yamamoto, Hiromasa; Schuch, Nelson Jorge; Agnez-Lima, Lucymara Fassarella; MacMahon, Ricardo Monreal; Menck, Carlos Frederico Martins

    2012-04-01

    Despite growing knowledge on the biological effects of ultraviolet (UV) radiation on human health and ecosystems, it is still difficult to predict the negative impacts of the increasing incidence of solar UV radiation in a scenario of global warming and climate changes. Hence, the development and application of DNA-based biological sensors to monitor the solar UV radiation under different environmental conditions is of increasing importance. With a mind to rendering a molecular view-point of the genotoxic impact of sunlight, field experiments were undertaken with a DNA-dosimeter system in parallel with physical photometry of solar UVB/UVA radiation, at various latitudes in South America. On applying biochemical and immunological approaches based on specific DNA-repair enzymes and antibodies, for evaluating sunlight-induced DNA damage profiles, it became clear that the genotoxic potential of sunlight does indeed vary according to latitude. Notwithstanding, while induction of oxidized DNA bases is directly dependent on an increase in latitude, the generation of 6-4PPs is inversely so, whereby the latter can be regarded as a biomolecular marker of UVB incidence. This molecular DNA lesion-pattern largely reflects the relative incidence of UVA and UVB energy at any specific latitude. Hereby is demonstrated the applicability of this DNA-based biosensor for additional, continuous field experiments, as a means of registering variations in the genotoxic impact of solar UV radiation. © 2012 Wiley Periodicals, Inc.

  20. Joule heating in the high-latitude mesosphere

    NASA Technical Reports Server (NTRS)

    Banks, P. M.

    1979-01-01

    The contribution made by Joule dissipation to heating of the daytime high-latitude upper mesosphere is discussed. During solar proton precipitation events in regions of large electric fields, Joule dissipation can be substantially larger than the local solar heating rate. Altitude profiles of Joule dissipation are presented for the polar cleft region for the August 4, 1972, solar proton event.

  1. More about the structure of the high latitude Jovian aurorae

    NASA Astrophysics Data System (ADS)

    Pallier, Laurent; Prangé, Renée

    2001-08-01

    This study is based on the determination of a 'reference' main oval for Jupiter's aurora from a series of high-resolution images taken with the Faint Object Camera on board the Hubble Space Telescope in the H 2 Lyman bands centered near 1550 Å. We have taken advantage of the visibility of the northern auroral oval over a large range of longitudes on June 24, 1994, especially for longitudes smaller than 170° where it is generally very faint and thus undetectable. In the south, where there is no such problem, we combined images taken from various points of view between June 1994 and September 1996. We find that the northern main oval is consistent in size and in general aspect with the footprint locus, in the Connerney (1998)'s VIP4 model, of magnetic field lines crossing the equator near 20 RJ. However, the precise shape of this oval differs from the model (and from previous 'reference' main ovals) in that it exhibits a 'bean-like' aspect with excursions toward lower latitudes in the SIII longitude range 190-240° (an already reported feature), and toward higher latitudes in the poorly documented 120-150° range. In the south, our reference oval covers an area about that of the 30 RJ VIP4 model. As in the north, it is shifted from a VIP4 model oval, toward lower latitudes from 110 to 200° and toward higher latitudes from 310 to 100°. The accurate definition of these (magnetically conjugate) oval loci puts additional strong constraints on magnetic field models at high latitude. Based on our reference main oval, we have then extrapolated still higher latitude ovals. Very interestingly, we find that we can fit (i) the highest latitude arc of oval detected well inside the main oval at longitudes greater than 170°, and (ii) the high latitude edge of what we had previously named the 'transpolar emission' at longitudes less than 170° (both also detected on images taken at other dates), by a single empirical oval. We suggest that this oval indicates the location of

  2. Energetic Particles at High Latitudes of the Heliosphere

    SciTech Connect

    Zhang Ming

    2004-09-15

    Ulysses has by now made two complete out-of-ecliptic orbits around the sun. The first encounter of the solar poles occurred in 1994-1995, when the sun was near the minimum of its activity cycle, while the second one was in 2000-2001, when the sun was at solar maximum. To our surprise, energetic particles of all origins at high latitude are not much different from those we observe near the ecliptic for at least these two phases of solar cycle. The latitude gradients of galactic and anomalous cosmic rays are positive but small at the 1994-1995 solar minimum and almost zero at the 2000-2001 solar maximum, while temporal solar cycle variation dominates their flux variation at all latitudes. Solar energetic particles from all large gradual events can be seen at both Ulysses and Earth no matter how large their spatial separations from the solar event are, and the particle flux often reaches a uniform level in the entire inner heliosphere within a few days after event onset and remains so throughout the decay phase that can sometimes last over a month. Energetic particles accelerated by low-latitude CIRs can appear at high latitudes, far beyond the latitudinal range of CIRs. All these observations suggest that latitudinal transport of energetic particles is quite easy. In addition, because the average magnetic field is radial at the pole, The Ulysses observations indicate that parallel diffusion and drift in the radial direction need to be reduced at the poles relative to their equatorial values. To achieve such behaviors of particle transport, the heliospheric magnetic field needs a significant latitudinal component at the poles. A non-zero latitudinal magnetic field component can be produced by latitudinal motion of the magnetic field line in solar corona, which can be in form of either random walk suggested by Jokipii or large scale systematic motion suggested by Fisk.

  3. Monitoring and Forecasting Ionospheric Scintillation at High Latitudes (Invited)

    NASA Astrophysics Data System (ADS)

    Prikryl, P.; Jayachandran, P. T.; Chadwick, R.; Kelly, T.

    2013-12-01

    Ionospheric scintillation (rapid signal amplitude fading and phase fluctuation) poses a threat to reliable and safe operation of modern technology that relies on Global Navigation Satellite Systems (GNSS). Ionospheric scintillation of GNSS signal severely degrades positional accuracy, causes cycle slips leading to loss of lock that affects performance of radio communication and navigation systems. At high latitudes, the scintillation is caused by ionospheric irregularities produced through coupling between solar wind plasma and the magnetosphere. Climatology of GPS scintillation at high latitudes in both hemispheres shows that phase scintillation occurs predominantly on the dayside in the cusp and in the nightside auroral oval. Solar wind disturbances, in particular the co-rotating interaction regions (CIR) on the leading edge of high-speed streams (HSS) and interplanetary coronal mass ejections (ICME), have been closely correlated with the occurrence of scintillation at high latitudes. These results demonstrated a technique of probabilistic forecast of high-latitude phase scintillation occurrence relative to arrival times of HSS and ICME. The Canadian High Arctic Ionospheric Network (CHAIN) has been monitoring GPS ionospheric scintillation and total electron content (TEC) since November 2007. One-minute amplitude and phase scintillation indices from L1 GPS signals and TEC from L1 and L2 GPS signals are computed from amplitude and phase data sampled at 50 Hz. Since 2012, significant expansion of CHAIN has begun with installation of new receivers, each capable of tracking up to 30 satellites including GLONASS and Galileo. The receivers log the raw phase and amplitude of the signal up to a 100-Hz rate for scintillation measurements. We briefly review observations of ionospheric scintillation and highlight new results from CHAIN, including the climatology of scintillation occurrence, collocation with aurora and HF radar backscatter, correlation with CIRs and ICMEs

  4. Electron spin resonance (ESR) dating of hominid-bearing deposits in the Caverna delle Fate, Ligure, Italy

    NASA Astrophysics Data System (ADS)

    Falgueres, Christophe; Yokoyama, Yuji; Bibron, Roland

    1990-07-01

    Stalagmitic floors interstratified with Mousterian deposits from the Caverna delle Fate (Italy) have been dated by the electron spin resonance (ESR) method. Three samples dated fall between 60,000 and 74,000 yr and indicate the age of the Mousterian deposits. They are in good agreement with ages determined by nondestructive γ-ray spectrometry of the human remains from 231Pa/ 235U and 230Th /234U ratios, which are, respectively, 75,000 -14,000+21,000 and 82,000 -25,000+36,000 yr. These dates are consistent with the morphological characteristics of the bones as Neanderthal remains.

  5. Geographic control of Titan's mid-latitude clouds

    NASA Astrophysics Data System (ADS)

    Roe, H. G.; Brown, M. E.; Schaller, E. L.; Bouchez, A. H.; Trujillo, C. A.

    2005-08-01

    Observations of tropospheric clouds (1-6) and the recent Huygens images of channels show that Titan has an active methane hydrological cycle. Titan's south polar clouds are now well known (3-5) and thought to be driven by small seasonal variations in surface temperature (3). The recent discovery (6) and continued observations (7) of significant cloud activity at 40oS latitude led to the suggestion that these mid-latitude clouds are the result of either seasonally evolving global circulation or surface geography (6). We report here further observations of Titan that clearly link the formation of the mid-latitude clouds to a region of Titan's surface centered at ˜350oW longitude, ˜40oS latitude. Analysis of the complete dataset does not support the earlier suggestion (6) that these clouds are a new phenomenon related to seasonal change. The strong link between geographic location and cloud formation along with the lack of evidence for seasonal change in the mid-latitude clouds leads to the conclusion that a geological mechanism is responsible for the formation of these clouds. We propose that geysers or cryovolcanism are sporadically active near ˜350oW longitude, ˜40oS latitude. The implied rate of volatile release would easily supply enough methane to balance the loss to photolytic chemistry in the upper atmosphere. 1. Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., Nature 395, 575-578 (1998). 2. Griffith, C.A., Hall, J.L., Geballe, T.R., Science 290, 509-513 (2000). 3. Brown, M.E., Bouchez, A.H., Griffith, C.A., Nature 420, 795-797 (2002). 4. Roe, H.G., de Pater, I., Macintosh, B.A., McKay, C.P., ApJ 581, 1399-1406 (2002). 5. Bouchez, A.H., Brown, M.E., ApJ 618, L53-L56 (2005). 6. Roe, H.G., Bouchez, A.H., Trujillo, C.A., Schaller, E.L., Brown, M.E., ApJ 618, L49-L52 (2005). 7. Porco, C.C., et al., Nature 434, 159-168 (2005). HGR is supported by an NSF Astronomy & Astrophysics Postdoctoral Fellowship (NSF AST-0401559). ELS is supported by an NSF Graduate

  6. Restless legs syndrome: relationship between prevalence and latitude.

    PubMed

    Koo, Brian B

    2012-12-01

    Restless legs syndrome (RLS) has a broad worldwide prevalence between 0.01% and 18.3%. While differences in RLS definitions and data ascertainment methods account for some variability, other factors likely contribute. The circadian nature of RLS and the fact that RLS symptoms track with endogenous melatonin levels suggest that light or ultraviolet radiation (UVR) may be related to RLS expression. As the amount of UVR decreases with latitude, we considered the potential effect of geography on RLS prevalence with the thought being that RLS prevalence rises with increasing latitude. RLS epidemiologic studies were sought via Pubmed search in the period between January 1, 1992 and November 15, 2010. Prevalence was mapped for each country or specific region studied and examined by continent. Pearson's correlational testing was carried out for RLS prevalence and latitude of the region studied. Global RLS prevalence ranges from 0.01% in Africa, 0.7% to 12.5% in Asia, 2.0% to 18.9% in the Americas, and 3.2% to 18.3% in Europe. Mapping RLS prevalence by country or region in both the Americas and in Europe suggests increasing RLS frequency with greater northern latitude. RLS prevalence is positively correlated with northern latitude in both North America and Europe with correlation coefficients of r = 0.77 (0.15, 0.96; p = 0.02) and r = 0.74 (0.44, 0.89; p = 0.0002), respectively. In Europe, lower latitudinal countries like Greece and Turkey had RLS prevalence (per 1,000 persons) of 38 and 34, respectively, middle latitudinal countries like France and England of 108 and 86, respectively, and high latitudinal countries like Norway and Iceland of 143 and 183, respectively. RLS epidemiology indicates an increase in RLS frequency in northern latitudinal countries as a function of distance from the equator, an effect most evident in Europe. This suggests that factors that track with latitude like UVR may be involved in the expression of RLS.

  7. Changing climate cues differentially alter zooplankton dormancy dynamics across latitudes.

    PubMed

    Jones, Natalie T; Gilbert, Benjamin

    2016-03-01

    In seasonal climates, dormancy is a common strategy that structures biodiversity and is necessary for the persistence of many species. Climate change will likely alter dormancy dynamics in zooplankton, the basis of aquatic food webs, by altering two important hatching cues: mean temperatures during the ice-free season, and mean day length when lakes become ice free. Theory suggests that these changes could alter diversity, hatchling abundances and phenology within lakes, and that these responses may diverge across latitudes due to differences in optimal hatching cues and strategies. To examine the role of temperature and day length on hatching dynamics, we collected sediment from 25 lakes across a 1800 km latitudinal gradient and exposed sediment samples to a factorial combination of two photoperiods (12 and 16 h) and two temperatures (8 and 12 °C) representative of historical southern (short photoperiod, warm) and northern (long photoperiod, cool) lake conditions. We tested whether sensitivity to these hatching cues varies by latitudinal origin and differs among taxa. Higher temperatures advanced phenology for all taxa, and these advances were greatest for cladocerans followed by copepods and rotifers. Although phenology differed among taxa, the effect of temperature did not vary with latitude. The latitudinal origin of the egg bank influenced egg abundance and hatchling abundance and diversity, with these latter effects varying with taxa, temperature and photoperiod. Copepod hatchling abundances peaked at mid-latitudes in the high temperature and long photoperiod treatments, whereas hatchling abundances of other zooplankton were greatest at low latitudes and high temperature. The overall diversity of crustacean zooplankton (copepods and cladocerans) also reflected distinct responses of each taxa to our treatments, with the greatest diversity occurring at mid-latitudes (~56 °N) in the shorter photoperiod treatment. Our results demonstrate that hatching cues

  8. Assessment of Plasma Transport and Convection at High Latitudes

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The high-latitude ionosphere is strongly coupled to the thermosphere and magnetosphere. The magnetospheric coupling occurs via electric fields, field-aligned currents, and particle precipitation. Owing to the interaction of the shocked solar wind with the geomagnetic field, an electric potential difference is generated across the tail of the magnetosphere, with the resulting electric field pointing from dawn to dusk. Energetic particle precipitation from the magnetosphere in the auroral region leads to the creation of ionization and to electron, ion, and neutral gas heating. In order to assess the current understanding of plasma transport and convection at high latitudes, it is necessary to take account of the strong coupling between the ionosphere, thermosphere, and magnetosphere.

  9. An energy principle for high-latitude electrodynamics

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1984-01-01

    A theoretical model for mid- and high-latitude electric fields and currents is constructed using Fourier analysis methods. A two-dimensional planar ionosphere with an enhanced conductivity auroral belt and field-aligned currents at the edges is employed. The postulate that the electric field and currents adjust self-consistently to minimize the global Joule dissipation rate defines a theoretical relation between the primary and secondary field-aligned currents. This so-called minimal dissipation configuration is examined using several input field-aligned current models, and graphical solutions for the electric field and ionospheric current are shown. A detailed discussion and interpretation of the solutions with relation to diverse observations and high-latitude phenomenology are included.

  10. CO observations of southern high-latitude clouds. [In Galaxy

    SciTech Connect

    Keto, E.R.; Myers, P.C.

    1986-05-01

    Results from a survey of 2.6 mm emission in the J = 1 to 0 transition of CO of clouds are reported for 15 high Galactic latitude clouds and three clouds located on the fringe of a large molecular cloud in the Chameleon dark cloud complex. The line widths, excitation temperatures, sizes, and n(CO)/N(H2) ratio of these clouds are similar to those seen in dark clouds. The densities, extinctions, and masses of the high-latitude clouds are one order of magnitude less than those found in dark clouds. For its size and velocity dispersion, the typical cloud has a mass of at least 10 times less than that needed to bind the cloud by self-gravity alone. External pressures are needed to maintain the typical cloud in equilibrium, and these values are consistent with several estimates of the intercloud pressure. 32 references.

  11. Uranus' Vertical Haze Structure and its Variation with Latitude

    NASA Astrophysics Data System (ADS)

    Tomasko, Martin

    1997-07-01

    We propose to image Uranus in 27 filters between 220 and 2100 nm wavelength. The wide wavelength range allows determination of aerosol sizes and spectral characteristics superior to previous work. Some of the filters are in methane absorption bands with methane absorption coefficients spanning a factor of 1000, which probe very different altitude layers in Uranus' atmosphere. HST's spatial resolution gives accurate canter-to -limb information for each latitude band, which strongly constrains models of Uranus' vertical haze structure. Our analyzed images of Uranus of Cycle 5 show high albedo contrasts in latitude, but the wavelength coverage of these images was not sufficient. These observations yielded unexpected results on the photometric properties of Uranian rings and satellites. Open questions about the phase function of these objects near zero degree and about their spectral characteristics over an expanded wavelength region can be answered by the proposed observations.

  12. Maritime User Requirements at High Latitudes - the MARENOR Project

    NASA Astrophysics Data System (ADS)

    Behlke, R.

    2014-12-01

    The ionosphere at high latitudes is characterised by a great variety of spatial and temporal variations that influence radio signals. In addition to navigation solutions that are based on Global Navigation Satellite Systems (GNSS), satellite communication systems also suffer from ionospheric degradation. This is worsened by harsh weather conditions, insufficient coverage by geostationary satellites and the absence of land-based augmentation infrastructure. Climate change will lead to a decrease in sea ice extent and thus to an increased use of trans-polar shipping routes, presence of gas and oil industries in the High Arctic and higher focus on Search-and-Rescue (SAR) as well as sovereignty issues. These moments usually require navigation and communication solutions that are accurate and reliable. We describe requirements presented by industrial operators on and around Svalbard. In addition, we present the MARENOR project that aims on evaluating navigation and communication systems at high latitudes including first results

  13. High latitude marine reserve research in Glacier Bay National Park

    USGS Publications Warehouse

    Taggart, S. James; Mondragon, Jennifer; Andrews, A.G.; Nielsen, J.K.

    2003-01-01

    Glacier Bay National Park and Preserve is dominated by the marine waters that make up nearly one-fifth of the park’s area. Since the late 1800s, the nutrient rich waters of Glacier Bay have supported highly productive commercial fisheries. Congress closed fishing in parts of Glacier Bay National Park in 1999, creating one of North America’s largest marine reserves. Throughout the world, marine reserves are being promoted as effective tools for managing fisheries while simultaneously meeting marine conservation goals and maintaining marine biodiversity. Increases in individual size, density, biomass, and diversity have been demonstrated in studies of fish and invertebrates from both temperate and tropical marine reserves (Halpern 2003). Studies on the effectiveness of marine reserves at high latitudes, however, are rare. The formation of marine reserves in Glacier Bay National Park provides a unique opportunity for marine reserve research in a high latitude ecosystem.

  14. High-Latitude Ionospheric Dynamics During Conditions of Northward IMF

    NASA Technical Reports Server (NTRS)

    Sharber, J. R.

    1996-01-01

    In order to better understand the physical processes operating during conditions of northward interplanetary magnetic field (IMF), in situ measurements from the Dynamics Explorer-2 (low altitude) polar satellite and simultaneous observations from the auroral imager on the Dynamics Explorer-1 (high altitude) satellite were used to investigate the relationships between optical emissions, particle precipitation, and convective flows in the high-latitude ionosphere. Field aligned current and convective flow patterns during IMF north include polar cap arcs, the theta aurora or transpolar arc, and the 'horse-collar' aurora. The initial part of the study concentrated on the electrodynamics of auroral features in the horse-collar aurora, a contracted but thickened emission region in which the dawn and dusk portions can spread to very high latitudes, while the latter part focused on the evolution of one type of IMF north auroral pattern to another, specifically the quiet-time horse-collar pattern to a theta aurora.

  15. Ulysses - The first high-latitude heliospheric mission

    NASA Technical Reports Server (NTRS)

    Wenzel, K.-P.; Marsden, R. G.; Page, D. E.; Smith, E. J.

    1989-01-01

    The Ulysses mission will, for the first time, explore the heliosphere within a few astronomical units of the sun over the full range of heliographic latitudes, thereby providing the first characterization of the uncharted third dimension. Highly sophisticated scientific instrumentation carried on board the spacecraft is designed to measure the properties of the solar wind, the sun/wind interface, the heliospheric magnetic field, solar radio bursts and plasma waves, solar X-rays, solar and galactic cosmic rays, and interplanetary/interstellar neutral gas and dust. This collaborative ESA/NASA mission, scheduled for launch in October 1990, will use a Jupiter gravity-assist to achieve a trajectory extending to high solar latitudes /1,2/.

  16. Spectral variability of the Martian high latitude surfaces

    NASA Astrophysics Data System (ADS)

    Poulet, F.; Langevin, Y.; Boubin, G.; Jouglet, D.; Bibring, J.-P.; Gondet, B.

    2008-10-01

    We report the surface distributions of some minerals in the high latitude (>50°) regions of Mars using the OMEGA/MEx observations in the near-infrared wavelength domains (1-2.5 μm). Mafic minerals (pyroxene and olivine) are observed in the low albedo terrains. The identification of these minerals is consistent with the presence of volcanic features identified by geologic mappings. Water-bearing minerals identified on the basis of the 1.9 μm band cover the surfaces of latitudes larger than 60°. The presence of this hydration is likely the result of diffusive exchange of water between the sub-surface ice, the pore space of the regolith and the atmosphere, rather than chemically bound water resulting from hydrous alteration during the formation of the minerals. These observations will allow for comprehensive, coordinated analyses of data from the orbital and Phoenix platforms.

  17. Determination and analysis of local seasonal terms of latitude variations

    NASA Astrophysics Data System (ADS)

    Soloducha, Barbara

    1991-03-01

    Local seasonal terms of latitude variations were determined on the basis of phi data of 17 BIH/IMPS stations and x, y, z data of the BIH global solution during the years 1967-1978. Some models for local corrections R to the latitude introduced by the BIH are created. The corrections R obtained from the least squares adjustment from one year data appear to be the best. The present study shows that it is necessary to determine these more frequently than once a year or to compute them for all stations simultaneously with the ERP. This will be particularly important in view of the future re-reduction of past astrometric data.

  18. Orbital control of low-latitude seasonality during the Eemian

    USGS Publications Warehouse

    Winter, Amos; Paul, A.; Nyberg, J.; Oba, T.; Lundberg, J.; Schrag, D.; Taggart, Bruce E.

    2003-01-01

    We used Sr/Ca and stable isotope data from well dated and preserved corals from the northeastern Caribbean to determine the seasonal environmental conditions for four continuous years during the Eemian, the last time the Earth was in a prolonged warm phase. We determined that the seasonal range in SST during the Eemian was 25°–30° C. This is ∼1–2° larger than at present and caused primarily by winter cooling and, only to a small degree, by summer warming. As climate modeling studies indicate, the bias towards colder winters can be explained by changes in low latitude insolation induced by altered orbital parameters, modulated by atmospheric CO2 levels that were lower than today. Milankovitch forcing at higher latitudes was probably less important.

  19. Arctic Amplification and Potential Mid-Latitude Weather Linkages

    NASA Astrophysics Data System (ADS)

    Overland, J. E.

    2014-12-01

    Increasing temperatures and other changes continued in the Arctic over the last decade, even though the rate of global warming has decreased in part due to a cool Pacific Ocean. Thus Arctic temperatures have increased at least 3 times the rate of mid-latitude temperatures. Credibility for persistent Arctic change comes from multiple indicators which are now available for multiple decades. Further, the spatial pattern of Arctic Amplification differs from patterns of natural variability. The role of the Arctic in the global climate system is based on multiple interacting feedbacks represented by these indicators as a causal basis for Arctic Amplification driven by modest global change. Many of these processes act on a regional basis and their non-linear interactions are not well captured by climate models. For example, future loss of sea ice due to increases in CO2 are demonstrated by these models but the rates of loss appear slow. It is reasonable to suspect that Arctic change which can produce the largest temperature anomalies on the planet and demonstrate recent extremes in the polar vortex could be linked to mid-latitude weather, especially as Arctic change will continue over the next decades. The meteorological community remains skeptical, however, in the sense of "not proven." Natural variability in chaotic atmospheric flow remains the main dynamic process, and it is difficult to determine whether Arctic forcing of a north-south linkage is emerging from the most recent period of Arctic change since 2007. Nonetheless, such a hypothesis is worthy of investigation, given the need to further understand Arctic dynamic atmospheric processes, and the potential for improving mid-latitude seasonal forecasts base on high-latitude forcing. Several AGU sessions and other forums over the next year (WWRP, IASC,CliC) address this issue, but the topic is not ready for a firm answer. The very level of controversy indicates the state of the science.

  20. Center is at Latitude 30 Degrees South, Longitude 210 Degrees

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Center of the orthographic projection is at latitude 30 degrees S., longitude 210 degrees. Toward the top, the lowland plains of Elysium and Utopia Planitiae are separated from the darker heavily cratered highlands by a broad escarpment. The far bottom left is marked by the large light-colored ancient Hellas impact basin. The permanent south polar residual ice cap is located near the bottom.

  1. Magnetospheric effects in atmospheric electricity at high latitudes

    NASA Astrophysics Data System (ADS)

    Shumilov, O. I.; Kasatkina, E. A.; Frank-Kamenetsky, A. V.; Raspopov, O. M.; Vasiljev, A. N.; Struev, A. G.

    2003-04-01

    Measurements of the vertical atmospheric electric field (Ez) made at auroral station Apatity (geomagnetic latitude: 63.8) and polar cap station Vostok, Antarctica (geomagnetic latitude: -89.3) in 2001-2002 have been analyzed. The measurements were made by a high-latitude computer-aided complex installed at Apatity in 2001. It consists of three spatially placed microbarographs for measurements of atmospheric waves, a device for air conductivity measurement and a device for measurement of vertical component of the atmospheric electric field. The computer-aided system permits to get information with a frequency of five times per second. The ground level atmospheric electric field was found to have systematic local diurnal and seasonal variations. Diurnal variations of atmospheric potential gradient were found to have a departure from the Carnegie curve. A distinct difference in the diurnal variation of atmospheric electric field has been observed also between disturbed (Kp>30) and extremely quiet (Kp<5) geomagnetic conditions. These high-latitude electric field variations appear to be the result of solar wind-magnetosphere-ionosphere coupling. Besides, we have found the similarity between the diurnal course of the atmospheric electric field under the quiet geomagnetic conditions and the diurnal variation of galactic cosmic rays. These results have been explained in terms of calculated effective Bz component of the interpalnetary magnetic field arising due to variation of the geomagnetic dipole axis inclination during the Earth's rotation. The results of analysis of the influence of extreme weather conditions (rain, snow, snowstorm, stormclouds, thunderstorms, lightning) on atmospheric electricity (electric field and conductivity) are also discussed. This work was supported by EC (grant INTAS 97-31008) and RFBR (grant 01-05-64850).

  2. On the nature of the unidentified high latitude UHURU sources

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Murray, S. S.; Giacconi, R.; Kellogg, E. M.; Matilsky, T. A.

    1973-01-01

    It is found that the unidentified high latitude UHURU sources can have either of two very different explanations. They must either reside at great distances with luminosity equivalent to or greater than 10 to the 46th power ergs/sec, or be contained in the galaxy with luminosity equivalent to or less than 10 to the 34th power ergs/sec. The two possibilities are indistinguishable with the available data.

  3. Ulysses at high latitudes: An overview of recent results

    NASA Technical Reports Server (NTRS)

    Marsden, R. G.; Smith, E. J.

    1996-01-01

    After its fly-by of the planet Jupiter in February 1992, the Ulysses spacecraft is now in a highly inclined heliocentric orbit that will bring it above the south polar regions of the Sun in September 1994. The high-latitude phenomena observed to date have been strongly influenced by the near-minimum solar activity conditions encountered during this phase of the mission. In late April 1993, when Ulysses was at approximately 29 deg S heliographic latitude, the recurrent high speed solar wind stream that had been observed at the location of the spacecraft for 11 consecutive solar rotation underwent a dramatic change. The wind speed in the valleys between successive peaks increased in a single step from approximately 420 km/s to aopproximately 560 km/s. This change in solar wind flow was accompanied by the disappearance at the spacecraft of the magnetic sector structure that had been observed until then. Both these finding are consistent with Ulysses having climbed beyond the latitude of the coronal streamer belt in which is embedded the heliospheric current sheet (HCS). In its subsequent poleward journey, no further evidence for an encounter with the HCS has been seen at Ulysses. Other phenomena observed include the evolution with latitude of corotating interaction region (CIRs) and their influence on the acceleration of energetic particles, and the characteristics of the solar wind flows emanating from the south polar coronal hole. In this paper, we present details of the above observations. Finally, while the polar passes of the prime mission will take place near solar minimum, an extended mission will bring Ulysses back over the poles near the maximum of the next cycle. A summary of scientific goals for Ulysses at solar maximum is given.

  4. Magnetic field maxima in the low latitude boundary layer

    NASA Technical Reports Server (NTRS)

    Sonnerup, B.; Paschmann, G.; Phan, T.-D.; Luehr, H.

    1992-01-01

    The magnetic field often exhibits a maximum in the earth's low-latitude boundary layer. Examples of this behavior are shown using data from the AMPTE/IRM spacecraft, and it is argued that two fundamentally distinct causes exist for the excess field: (1) a depression, within the layer, of the population of medium-energy ions of magnetospheric origin and (2) field curvature effects associated with undulations of the magnetopause itself.

  5. On the Conjugacy of the Aurora: High and Low Latitudes.

    DTIC Science & Technology

    1988-02-05

    AD43 00 ON TNE COWJUGACY OF THE AROM : HIGH AND LOW LATITUDES vi1 (U) AROSPACE CORP EL SEGUNDO CR SPACE SCIENCES LAD P IZERM ET RAL. 05 FEB GO TR-*M...and reentry fluid mechanics, heat transfer and flight dynamics; chemical and electric propulsion, propellant chemistry , chemical dynamics...environmental chemistry , trace detection; spacecraft structural mechanics, contamination, thermal and structural control; high temperature thermomechanics, gas

  6. The High Latitude D Region During Electron Precipitation Events

    NASA Technical Reports Server (NTRS)

    Hargreaves, J. K.; Collis, P. N.; Korth, A.

    1984-01-01

    The fluxes of energetic electrons entering the high-latitude atmosphere during auroral radio absorption events and their effect on the electron density in the auroral D region are discussed. An attempt was made to calculate the radio absorption during precipitation events from the fluxes of energetic electrons measured at geosynchronous orbit, and then to consider the use of absorption measurements to indicate the magnetospheric particle fluxes, the production rates, and electron densities in the D region.

  7. Physiological and behavioral adaptations in bats living at high latitudes.

    PubMed

    Boyles, Justin G; McGuire, Liam P; Boyles, Esmarie; Reimer, Jesika P; Brooks, Christopher A C; Rutherford, Robert W; Rutherford, Teresa A; Whitaker, John O; McCracken, Gary F

    2016-10-15

    Widespread animals at the extremes of the species' distribution experience ecological constraints different than individuals in the core of the distribution. For example, small endotherms at very high latitudes face short summers with cool temperatures and a lack of true darkness. In particular, insectivorous bats at high latitudes may experience constraints because of their unique life history traits, and may have different energy requirements than bats at lower latitudes. To evaluate the extent of these differences, we estimated an energy budget and refueling rates for reproductively active female little brown bats (Myotis lucifugus) roosting in buildings in eastern Alaska (~63°N). Physiological parameters (torpor use and metabolic rates) and daily energy expenditures (25.7±5.3kJd(-1)) were similar to, or slightly lower than, conspecifics at lower latitudes. Northern little brown bats foraged for less time than southerly conspecifics, but measurements of plasma β-hydroxybutyrate concentrations suggest that northern bats refuel at a rate considerably higher than those to the south. It appears that high refueling rates (and therefore foraging intensity) involve a dietary shift to orb-weaver spiders, which are abundant and likely offer higher energetic benefit than the small, flying insects consumed by individuals in other parts of the distribution. Environmental factors may limit species' distributions, but our results provide an example of a population at the limit of their geographic range that has compensated for environmental challenges by adopting unique behavioral strategies while the underlying physiology (including daily energy expenditure) remains similar to populations at the core of the species' range. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Boundary Current and Mixing Processes in The High Latitude Oceans

    DTIC Science & Technology

    2016-06-07

    Boundary Current and Mixing Processes in The High Latitude Oceans Robin D. Muench Earth & Space Research 1910 Fairview Ave E., Ste 210 Seattle...ORGANIZATION NAME(S) AND ADDRESS(ES) Earth & Space Research,1910 Fairview Ave E., Ste 210,Seattle,WA,98102 8. PERFORMING ORGANIZATION REPORT NUMBER 9...for field platforms and instrumentation used for data collection. Laurence Padman ( Earth & Space Research) has been the primary collaborator. Other

  9. Effects of ionospheric disturbances on high latitude radio wave propagation

    NASA Astrophysics Data System (ADS)

    Larsen, T. R.

    The effects of anomalous high-latitude ionization on radio wave propagation are described for the main types of disturbances, that is, sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, and polar cap events. Examples of radio wave characteristics for such conditions are given for the frequencies between the very low (3-3000 Hz) and high (3-30 MHz) frequency domains.

  10. Specific problems associated with photography in tropical latitudes.

    PubMed

    Shapter, M

    1994-04-01

    This article looks at problems, which may not be encountered in other places, associated with photography in tropical latitudes. It deals with the effects of high air temperatures and high water temperatures as they relate to film exposure, processing and storage. It mentions the effect of tropical conditions on photographic equipment, and difficulties in obtaining materials because of distances from suppliers to delivery point, with reference to the author's experiences in Townsville, Queensland, Australia.

  11. USGS research on three mid-latitude glaciers

    USGS Publications Warehouse

    Green, J.R.; DeWayne, Cecil L.; Naftz, D.L.; Schuster, P.F.

    2000-01-01

    Low- and mid-latitude regions of the earth are home to 80 to 90 percent of the world's population. Because of this, the U.S. Geological Survey (USGS) is conducting a research program to study the geochemistry of precipitation, snow, ice, and runoff samples from mid-latitude glaciers in Kyrghyzstan, Nepal, and the United States, Areas of research, such as ground-water studies, reconstructing paleoclimate records, describing anthropogenic input of chemicals to the environment, and modeling global climate, are important to the well being of the worlds' population and can be supplemented by the collection and chemical analysis of snow and ice cores. Nearly all the constituents that compose snow and ice-core samples contribute vital information, whether it be the microbial communities that flourish in snow, radionuclides present in various amounts in all the samples, or location-specific deposits of mercury and nitrate. This work is hastened by the fact that mid-latitude glaciers, and the information preserved in them, are rapidly disappearing as a result of global warming. Research collaboration for this project includes 12 national and 7 international universities, and 4 government agencies. Funding is provided by the National Science Foundation, the U.S. Department of Energy, and the USGS.

  12. Mid-latitude lidar observations of large sporadic sodium layers

    SciTech Connect

    Senft, D.C.; Collins, R.L.; Gardner, C.S. )

    1989-07-01

    During the early morning of October 31, 1988 two large sporadic Na (Na{sub s}) layers were observed near the mesopause above Urbana, IL (40{degree}N, 88{degree}W) with a Na lidar system. The layers began forming near 102 km at 0026 LST and 0110 LST and moved downward with vertical velocities as high as 4 ms{sup {minus}1} before dissipating between 94 and 96 km. The duration of each layer was approximately 80 min. The layers were narrow ({approximately} 1 km FWHM) and dense with maximum densities approaching 7,800 cm{sup {minus}3}. The characteristics of these two Na{sub s} layers are very similar to those of similar phenomena observed recently at Andoya, Norway and Mauna Kea, Hawaii. Lidar observations of the mesospheric Na layer have been conducted routinely by several groups at mid-latitudes for almost 20 years. Although large Na{sub s} layers now appear to be relatively common at low- and high-latitudes, to our knowledge the two layers described in this letter are only the second observation of this puzzling phenomenon at mid-latitudes.

  13. Electrodynamic structure of the morning high-latitude trough region

    NASA Astrophysics Data System (ADS)

    Vanhamäki, H.; Aikio, A.; Voiculescu, M.; Juusola, L.; Nygrén, T.; Kuula, R.

    2016-03-01

    We describe the electrodynamics of a postmidnight, high-latitude ionospheric trough, observed with the European Incoherent Scatter radar in northern Scandinavia on 24-25 June 2003 around 22:00-02:30 UT during quiet conditions. The UHF radar made meridian scans with a 30 min cadence resulting in nine cross sections of ionospheric parameters. The F region electric field was also determined with the tristatic system. Ionospheric equivalent currents, calculated from ground magnetometer data, mostly show an electrojet-like current that is reasonably uniform in the longitudinal direction. Combined analysis of the conductances and equivalent current with a local Kamide-Richmond-Matsushita (KRM) method yields the ionospheric electric field and field-aligned current (FAC) in a 2-D (latitude-longitude) area around the radar. We conclude that the most likely scenario is one where the trough is initially created poleward of the auroral oval by downward FAC that evacuates the F region, but as the trough moves to lower latitudes during the early morning hours, it becomes colocated with the westward electrojet. There the electron density further decreases due to increased recombination caused by enhanced ion temperature, which in turn is brought about by a larger convection speed. Later in the morning the convection speed decreases and the trough is filled by increasing photoionization.

  14. Diversity-stability relationship varies with latitude in zooplankton.

    PubMed

    Shurin, Jonathan B; Arnott, Shelley E; Hillebrand, Helmut; Longmuir, Allyson; Pinel-Alloul, Bernadette; Winder, Monika; Yan, Norman D

    2007-02-01

    Analyses of temporal patterns of diversity across a wide range of taxa have found that more diverse communities often show smaller compositional changes over time. This generality indicates that high diversity is associated with greater temporal stability in species composition. We examined patterns of diversity and community stability in zooplankton time series data from 36 lakes sampled over a combined 483 years. The species-time relationship was flatter in more species-rich lakes in the temperate zone. However, high-latitude lakes had both low richness and low turnover. These patterns were consistent for turnover both within and among years. Daily, annual and long-term richness were all higher in large lakes while turnover was unaffected by the surface area. Richness on all time scales, as well as turnover within and among years, all declined at high latitude. Species-area relations and latitudinal gradients in richness therefore reflect different temporal components of diversity. Our results suggest that diversity shows strong associations with compositional stability that vary qualitatively across biogeographical provinces. Community stability increases with diversity among lakes in the temperate zone; however, the two are negatively correlated across latitudinal gradients. These patterns indicate that either the direct effects of diversity on stability or their covariance with environmental fluctuations vary with latitude.

  15. Atmospheric river landfall-latitude changes in future climate simulations

    NASA Astrophysics Data System (ADS)

    Shields, Christine A.; Kiehl, Jeffrey T.

    2016-08-01

    The latitude of landfall for atmospheric rivers (ARs) is examined in the fully coupled half-degree version of the Community Climate System Model, version 4 (CCSM4) for warm future climate simulations. Two regions are examined: U.S. West Coast/North Pacific ARs and United Kingdom/North Atlantic ARs. Changes in AR landfall-latitude reflect changes in the atmospheric steering flow. West Coast U.S. ARs are projected to push equatorward in response to the subtropical jet climate change. UK AR response is dominated by eddy-driven jets and is seasonally dependent. UK simulated AR response is modest in the winter with the largest relative changes occurring in the seasonal transition months. Precipitation associated with ARs is also projected to increase in intensity under global warming. CCSM4 projects a marked shift to higher rainfall rates for Southern California. Small to modest rainfall rates may increase for all UK latitudes, for the Pacific Northwest, and central and northern California.

  16. Recent Advances in Mid-latitude Ionosphere/Thermosphere Science

    NASA Astrophysics Data System (ADS)

    Kelley, Michael

    One of the original reasons for building a National Ionospheric Observatory (now the National Astronomy and Ionospheric Center or NAIC) near Arecibo, Puerto Rico was the location, which is in the best behaved region of the ionosphere. At 30° magnetic latitude and 19° geographic latitude, it is well equatorward of the auroral and sub-auroral zones and poleward of the equatorial anomalies most of the time. The island thus has some of the best weather and space weather on the planet. However, similar to an occasional hurricane striking the island, the ionosphere overhead has occasional ionospheric and thermospheric disturbances. Some of these space weather phenomena, e.g., mesoscale TIDs and unstable sporadic E layers, are endemic to the region and, prior to the advent of airglow imagers and GPS networks, were difficult to visualize using radiowave data alone. Other weather events are caused by infringement on this zone from processes in more active weather regions. For example, neutral waves launched from the auroral oval (large scale TIDs) pass through the region; electric fields penetrate from the solar wind and create both plasma uplifts, causing positive ionospheric storms, and stormenhanced density plumes, coursing through the region. From the south, convective equatorial ionospheric storms create plasma bubbles that can reach mid-latitudes. Examples of data obtained during these phenomena, and possibly more, will be presented and discussed in light of our present understanding.

  17. A New Impact Site in the Southern Middle Latitudes

    NASA Image and Video Library

    2017-04-05

    Over 500 new impact events have been detected from before-and-after images from NASA's Mars Reconnaissance Orbiter, mostly from MRO's Context Camera, with a HiRISE followup. Those new craters that expose shallow ice are of special interest, especially at latitudes where not previously detected, to better map the ice distribution. We hope to find ice at relatively low latitudes both for understanding recent climate change and as a resource for possible future humans on Mars. This new impact, which occurred between August and December 2016 (at 42.5 degree South latitude) would provide an important constraint if ice was detected. Alas, the HiRISE color image does not indicate that ice is exposed. There is an elongated cluster of new craters (or just dark spots where the craters are too small to resolve), due to an oblique impact in which the bolide fragmented in the Martian atmosphere. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.1 centimeters (9.9 inches) per pixel (with 1 x 1 binning); objects on the order of 75 centimeters (29.5 inches) across are resolved.] North is up. https://photojournal.jpl.nasa.gov/catalog/PIA21578

  18. High-latitude space weather monitoring in Finland

    NASA Astrophysics Data System (ADS)

    Ulich, Th.

    2009-04-01

    Today, space weather is of important concern in many respects. Space weather phenomena are subject of extensive scientific research programmes and the consequences of space weather events are of great operational concern for a number of technologies including satellites, humans in space, and global positioning and communications. Due to the Earth's magnetic field, the high latitudes are most strongly affected by space weather phenomena. Naturally, monitoring and understanding of the high-latitude space environment is important for forecasting and modelling operational conditions. The Sodankylä Geophysical Observatory (SGO) was established as a magnetic observatory in 1913. With the sole exception of a year at the end of WWII, the record of geomagnetic field variations is continuous. Since the IGY in 1957, many other routine measurements have been added to the observatory's operations and today SGO is a highly versatile observatory. Here we will present examples of high-latitude space weather data from a selection of instruments including the Sodankylä ionosonde, the Finnish Riometer Chain, and the Tomography (GNSS) receiver chain. We invite collaboration and use of our data products. We will further outline the current EU Framework VII "Access to Research Infrastructures" project of SGO "LAPBIAT2."

  19. Ionospheric signatures of cusp latitude Pc 3 pulsations

    NASA Technical Reports Server (NTRS)

    Engebretson, M. J.; Anderson, B. J.; Cahill, L. J., Jr.; Arnoldy, R. L.; Rosenberg, T. J.

    1990-01-01

    Search coil magnetometer, riometer, photometer, and ELF-VLF receiver data obtained at South Pole Station and McMurdo, Antarctica during selected days in March and April 1986 are compared. Narrow-band magnetic pulsations in the Pc 3 period range are observed simultaneously at both stations in the dayside sector during times of low IMF cone angle, but are considerably stronger at South Pole, which is located at a latitude near the nominal foot point of the dayside cusp/cleft region. Pulsations in auroral light at 427.8 nm wavelength are often observed with magnetic pulsations at South Pole, but such optical pulsations are not observed at McMurdo. The observations suggest that precipitating magnetosheathlike electrons at nominal dayside cleft latitudes are at times modulated with frequencies similar to those of upstream waves. These particles may play an important role, via modification of ionospheric currents and conductivities, in the transmission of upstream wave signals into the magnetosphere and in the generation of dayside high-latitude Pc 3 pulsations.

  20. Mid-latitude afforestation shifts general circulation and tropical precipitation

    PubMed Central

    Swann, Abigail L. S.; Fung, Inez Y.; Chiang, John C. H.

    2012-01-01

    We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with latent heat flux due to water limitation. Atmospheric circulation redistributes the anomalous energy absorbed in the northern hemisphere, in particular toward the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid-latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water-limited regions. Mid-latitude afforestation is found to have a small impact on modeled global temperatures and on global CO2, but regional heating from the increase in forest cover is capable of driving unintended changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation. PMID:22190490

  1. Modeling Suspersonic Flow in the High-Latitude Thermosphere

    NASA Astrophysics Data System (ADS)

    Demars, H. G.; Schunk, R. W.

    2007-12-01

    Supersonic flow has been observed in the high-latitude thermosphere via DE-2 satellite measurements. The supersonic flow events were observed to occur most frequently in the dawn sector at high magnetic latitudes and in the altitude range from about 300-600 km. To gain theoretical insight into these supersonic flow events, we used a high-resolution model of the global thermosphere to study the geophysical conditions that give rise to supersonic flow. In particular, we considered the dependence of the neutral wind on IMF orientation, magnetic activity level, convection pattern shape, solar activity level, season, and universal time. We also studied the extent to which narrow plasma convection channels can induce supersonic neutral winds. We found that the predominant factor controlling the thermospheric wind speed at high latitudes is the magnitude of the cross- polar-cap potential, indicating that interaction with the convecting ionosphere can drive the thermosphere to supersonic speeds. The region of supersonic flow predicted by the model corresponds closely to the region where supersonic flow events were most frequently observed by the DE satellite.

  2. Impacts of climate warming on terrestrial ectotherms across latitude

    PubMed Central

    Deutsch, Curtis A.; Tewksbury, Joshua J.; Huey, Raymond B.; Sheldon, Kimberly S.; Ghalambor, Cameron K.; Haak, David C.; Martin, Paul R.

    2008-01-01

    The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest. PMID:18458348

  3. Impacts of climate warming on terrestrial ectotherms across latitude.

    PubMed

    Deutsch, Curtis A; Tewksbury, Joshua J; Huey, Raymond B; Sheldon, Kimberly S; Ghalambor, Cameron K; Haak, David C; Martin, Paul R

    2008-05-06

    The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.

  4. Mid-latitude afforestation shifts general circulation and tropical precipitation.

    PubMed

    Swann, Abigail L S; Fung, Inez Y; Chiang, John C H

    2012-01-17

    We show in climate model experiments that large-scale afforestation in northern mid-latitudes warms the Northern Hemisphere and alters global circulation patterns. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with latent heat flux due to water limitation. Atmospheric circulation redistributes the anomalous energy absorbed in the northern hemisphere, in particular toward the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid-latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water-limited regions. Mid-latitude afforestation is found to have a small impact on modeled global temperatures and on global CO(2), but regional heating from the increase in forest cover is capable of driving unintended changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation.

  5. Stable isotope variations in the Quaternary epithermal calcite-fluorite deposit at Monte delle Fate near Cerveteri (Latium, central Italy)

    USGS Publications Warehouse

    Masi, U.; O'Neil, J.R.

    1980-01-01

    Carbon, oxygen and hydrogen isotope variations have been measured in samples from the epithermal fluorite vein deposit at Monte delle Fate, Latium. The ranges in ?? 13C and ??18O of calcite are -1.3 to 3.4 and 9.5 to 17.3, respectively. ??D values of water extracted from fluid inclusions are -49 to -39 for calcite and -41 to -34 for fluorite. Fluid inclusion filling temperatures (225??-240??C) and salinites (3.75) are nearly the same for both fluorite and sparry calcite. An elongated form of calcite, of minor abundance, precipitated at lower temperatures. The data indicate that (1) the CO2 involved in the mineralization was provided by the local marine limestones, (2) the waters were meteoric in origin and underwent an 18O shift of ??? 10 permil by exchange with marine country rocks, and (3) all geochemical features can be explained by the action of two hydrothermal fluids. Hot brines recently discovered in the Cesano geothermal area, 30 km to the east, have temperatures and some chemical characteristics similar to the hydrothermal fluids at Monte delle Fate. ?? 1980 Springer-Verlag.

  6. Geophysical investigations at the Paleolitic site Grotta delle Veneri near Parabita (Lecce, Italy)

    NASA Astrophysics Data System (ADS)

    Carrozzo, M. T.; Leucci, G.; Negri, S.; Nuzzo, L.

    2003-04-01

    The human presence in Apulia (southern Italy) is documented since 80.000 years before present. In 1966 near Parabita (Lecce, Italy) in a cave subsequently named "Grotta delle Veneri" human remains belonging to Homo Sapiens Neanderthalensis (Neanderthal) and Homo Sapiens-Sapiens (Cro-Magnon) were recovered together with two small statues of pregnant women ("Veneri") referable to 12.000--10.000 b.C. The local Archaeological Superintendence was interested in assessing the possibility to reconstruct by means of geophysical methods the planimetric position of the cave and further development of its burrows beyond those accessible to speleologists and reported in the underground topographic survey. Both electromagnetic (EM) and electric methods were tested using Ground Penetrating Radar (GPR) with 200 and 500 MHz antennas, GEM300 multi-frequency EM induction device and 2D Electrical Resistivity Tomography (ERT). Despite the rough surface and the presence of numerous obstacles (trees, stone walls and stone piles) limiting the accessible survey area and often preventing a good ground-coupling, the GPR survey successfully located the top of the karstic cave and identified zones of high density of diffraction hyperbolas, interpreted as highly fractured and karstified limestone, in a layer ranging from about 2 m to 6 m below ground. Zones characterised by high density of diffractions due to presence of voids were found also outside the known development of the cave. By means of the GEM 300, both in-phase and quadrature components of the induced EM signal were simultaneously collected at 8 frequencies, from 2025 to 19975 Hz, respectively related to the magnetic susceptibility and apparent conductivity of the soil down to a depth decreasing as the frequency increase. A presumable low contrast in the sought parameter between the highly fractured rock and karstic voids or refilled cavities as well as the presence of metallic debris on the ground allowed a difficult identification

  7. Microphysical Ice Crystal Properties in Mid-Latitude Frontal Cirrus

    NASA Astrophysics Data System (ADS)

    Schlage, Romy; Jurkat, Tina; Voigt, Christiane; Minikin, Andreas; Weigel, Ralf; Molleker, Sergej; Klingebiel, Marcus; Borrmann, Stephan; Luebke, Anna; Krämer, Martina; Kaufmann, Stefan; Schäfler, Andreas

    2015-04-01

    Cirrus clouds modulate the climate by reflection of shortwave solar radiation and trapping of longwave terrestrial radiation. Their net radiative effect can be positive or negative depending on atmospheric and cloud parameters including ice crystal number density, size and shape. Latter microphysical ice crystal properties have been measured during the mid-latitude cirrus mission ML-CIRRUS with a set of cloud instruments on the new research aircraft HALO. The mission took place in March/April 2014 with 16 flights in cirrus formed above Europe and the Atlantic. The ice clouds were encountered at altitudes from 7 to 14 km in the typical mid-latitude temperature range. A focus of the mission was the detection of frontal cirrus linked to warm conveyor belts (WCBs). Within WCBs, water vapor is transported in the warm sector of an extra-tropical cyclone from the humid boundary layer to the upper troposphere. Cirrus cloud formation can be triggered in the WCB outflow region at moderate updraft velocities and additionally at low updrafts within the high pressure system linked to the WCB. Due to their frequent occurrence, WCBs represent a major source for regions of ice supersaturation and cirrus formation in the mid-latitudes. Here, we use data from the Cloud and Aerosol Spectrometer with detection for POLarization (CAS-POL) and the Cloud Combination Probe (CCP), combining a Cloud Droplet Probe (CDP) and a greyscale Cloud Imaging Probe (CIPgs) to investigate the ice crystal distribution in the size range from 0.5 µm to 1 mm. We derive microphysical cirrus properties in mid-latitude warm front cirrus. Further, we investigate their variability and their dependence on temperature and relative humidity. Finally, we compare the microphysical properties of these frontal cirrus to cirrus clouds that formed at low updrafts within high pressure systems or at high updraft velocities in lee waves. We quantify statistically significant differences in cirrus properties formed in these

  8. Titan's Stratospheric Condensibles at High Northern Latitudes During Northern Winter

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie; Samuelson, R.; Achterberg, R.

    2012-01-01

    The Infrared Interferometer Spectrometer (IRIS) instrument on board Voyager 1 caught the first glimpse of an unidentified particulate feature in Titan's stratosphere that spectrally peaks at 221 per centimeter. Until recently, this feature that we have termed 'the haystack,' has been seen persistently at high northern latitudes with the Composite Infrared Spectrometer (CIRS) instrument onboard Cassini, The strength of the haystack emission feature diminishes rapidly with season, becoming drastically reduced at high northern latitudes, as Titan transitions from northern winter into spring, In contrast to IRIS whose shortest wavenumber was 200 per centimeter, CIRS extends down to 10 per centimeter, thus revealing an entirely unexplored spectral region in which nitrile ices have numerous broad lattice vibration features, Unlike the haystack, which is only found at high northern latitudes during northern winter/early northern spring, this geometrically thin nitrile cloud pervades Titan's lower stratosphere, spectrally peaking at 160 per centimeter, and is almost global in extent spanning latitudes 85 N to 600 S, The inference of nitrile ices are consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by a mixture of HCN and HC3N, The narrow range in altitude over which the nitrile ices extend is unlike the haystack, whose vertical distribution is significantly broader, spanning roughly 70 kilometers in altitude in Titan's lower stratosphere, The nitrile clouds that CIRS observes are located in a dynamically stable region of Titan's atmosphere, whereas CH4 clouds, which ordinarily form in the troposphere, form in a more dynamically unstable region, where convective cloud systems tend to occur. In the unusual situation where Titan's tropopause cools significantly from the HASI 70.5K temperature minimum, CH4 should condense in Titan's lower stratosphere, just like the aforementioned nitrile clouds, although

  9. Ultraviolet light exposure influences skin cancer in association with latitude.

    PubMed

    Rivas, Miguel; Araya, María C; Caba, Fresia; Rojas, Elisa; Calaf, Gloria M

    2011-04-01

    The increase in the amount of solar ultraviolet (UV) light that reaches the earth is considered to be responsible for the worldwide increase in skin cancer. It has been reported that excessive levels of UVA and UVB light have multiple effects, which can be harmful to humans. Experimental measurements were obtained using wide-band solar light YES biometers from 2006 to 2009 in Arica, Chile and from 2003 to 2006 in Valdivia, Chile, both instruments having been calibrated according to the World Health Organization (WHO) criteria and integrated into the Chilean Meteorological Organization network. To explain the possible effect of radiation on skin cancer, revised pathological reports in Arica and Valdivia were analyzed. In Arica, data on men and women were collected between 1997 and 1998-2002, and in Valdivia, between 1997-2000 and 2001-2007. In this study, comparative values of ultraviolet index (UVI) from the above datasets, were analyzed. Arica is a city located in the subtropical zone of northern Chile, 25 meters above sea level, with a latitude of 18˚49'S and a longitude of 70˚19'W. It has a microclimate characterized by stable meteorological conditions throughout the year, including low precipitation (<5 mm per decade), predictable winds, a high percentage of clear sky days and high ground reflectivity due to the presence of light sand. Due to its location near sea level, the population performs a great number of outdoor activities. Valdivia is a city located in the southern part of Chile, 19 meters above sea level with a latitude of 39˚38'S and a longitude of 73˚5'W. The aim of the present study was to determine the relationship between latitude and the risk of skin cancer in two cities with different latitudes. The incidence of skin cancer per 100,000 persons significantly (P<0.05) increased in both genders between the periods 1997-2000 and 2001-2007 in Arica. However, it decreased in men between the periods 1993-1997 and 1998-2002 in Valdivia. The results

  10. Titan's stratospheric condensibles at high northern latitudes during northern winter

    NASA Astrophysics Data System (ADS)

    Anderson, C.; Samuelson, R.; Achterberg, R.

    2012-04-01

    The Infrared Interferometer Spectrometer (IRIS) instrument on board Voyager 1 caught the first glimpse of an unidentified particulate feature in Titan’s stratosphere that spectrally peaks at 221 cm-1. Until recently, this feature that we have termed ‘the haystack,’ has been seen persistently at high northern latitudes with the Composite Infrared Spectrometer (CIRS) instrument onboard Cassini. The strength of the haystack emission feature diminishes rapidly with season, becoming drastically reduced at high northern latitudes, as Titan transitions from northern winter into spring. In contrast to IRIS whose shortest wavenumber was 200 cm-1, CIRS extends down to 10 cm-1, thus revealing an entirely unexplored spectral region in which nitrile ices have numerous broad lattice vibration features. Unlike the haystack, which is only found at high northern latitudes during northern winter/early northern spring, this geometrically thin nitrile cloud pervades Titan’s lower stratosphere, spectrally peaking at 160 cm-1, and is almost global in extent spanning latitudes 85°N to 60°S. The inference of nitrile ices are consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by a mixture of HCN and HC3N. The narrow range in altitude over which the nitrile ices extend is unlike the haystack, whose vertical distribution is significantly broader, spanning roughly 70 km in altitude in Titan’s lower stratosphere. The nitrile clouds that CIRS observes are located in a dynamically stable region of Titan’s atmosphere, whereas CH4 clouds, which ordinarily form in the troposphere, form in a more dynamically unstable region, where convective cloud systems tend to occur. In the unusual situation where Titan’s tropopause cools significantly from the HASI 70.5K temperature minimum, CH4 should condense in Titan’s lower stratosphere, just like the aforementioned nitrile clouds, although in significantly larger

  11. Zonally Averaged Carbon Dioxide Concentration from Earth Mid-Troposphere at Different Latitudes, 2002 to 2013

    NASA Image and Video Library

    2013-05-22

    This plot shows the concentration of carbon dioxide in Earth mid-troposphere at various latitudes as measured by NASA Aqua satellite. The colored lines represent different latitude bands that circle Earth, called zones.

  12. Simulating Children's Retrieval Errors in Picture-Naming: A Test of Foygel and Dell's (2000) Semantic/Phonological Model of Speech Production

    ERIC Educational Resources Information Center

    Budd, Mary-Jane; Hanley, J. Richard; Griffiths, Yvonne

    2011-01-01

    This study investigated whether Foygel and Dell's (2000) interactive two-step model of speech production could simulate the number and type of errors made in picture-naming by 68 children of elementary-school age. Results showed that the model provided a satisfactory simulation of the mean error profile of children aged five, six, seven, eight and…

  13. Assessing Values in Historical Fiction Written for Children: A Content Analysis of the Winners of the Scott O'Dell Historical Fiction Award.

    ERIC Educational Resources Information Center

    Edgington, William D.; Brabham, Edna Greene; Frost, Jami Bice

    1999-01-01

    Considers how teachers engage children in character education and analyzes core values in books winning the Scott O'Dell Historical Fiction Award. Finds that these books are rich sources for examples of core values that are common features of character-education programs. Observes many teachers using short stories and picture books to insert…

  14. RIVER DELL CENTER FOR THE PROMOTION OF THE HUMANITIES. PROGRESS REPORT ON PRINTED INFORMATION, CONFERENCES AND VISITATIONS TO NOVEMBER 30, 1966. (TITLE SUPPLIED).

    ERIC Educational Resources Information Center

    River Dell Regional Schools, Oradell, NJ.

    THIS REPORT CITES THE PROGRESS AND ACCOMPLISHMENTS OF THE RIVER DELL CENTER. INFORMATION IS PRESENTED OF (1) PRINTED RELEASES, (2) CONTACTS MADE, (3) ON INSERVICE COURSE OFFERED, (4) DISSEMINATION OF COURSE INFORMATION, (5) VISITATIONS, AND (6) IN-PROGRESS ACTIVITIES. TWO REGIONAL SCHOOL NEWSLETTERS ALONG WITH CORRESPONDENCE LETTERS TO THE NEW…

  15. Assessment of polycyclic aromatic hydrocarbons (PAHs) in soil of a Natural Reserve (Isola delle Femmine) (Italy) located in front of a plant for the production of cement.

    PubMed

    Orecchio, Santino

    2010-01-15

    Isola delle Femmine Natural Reserve is a very little isle about 15 km from the centre of Palermo, in front of a plant for the production of cement and about 600 m from coast. In the present research, profiles soil PAHs were obtained for 16 sites within the reserve and for 8 stations on the rural soil taken as reference. summation Sigma PAHs, in the soil of investigated area, ranged from 35 to 545 microg/kg. With the aim to find the origin of PAHs in the soil of Isola delle Femmine, we compare the distribution of single analytes in the investigated area with those of the reference rural area (Monte Raffo Rosso), with those of atmospheric urban particulate collected at Palermo along with reported of emissions of some cement plants. The island's investigated area showed a high amount of 4- and 5-rings PAHs, whereas 3-ring PAHs are present mainly in the emission of cement plants (from literature). The percentage of 3-, 4-, 5- and 6-rings PAHs determined in samples of Isola delle Femmine are similar to those of the reference rural soils and to those of urban atmospheric particulate. Cement plant activity has a negligible weight on the presence of PAHs in the soil of Isola delle Femmine.

  16. Assessing Values in Historical Fiction Written for Children: A Content Analysis of the Winners of the Scott O'Dell Historical Fiction Award.

    ERIC Educational Resources Information Center

    Edgington, William D.; Brabham, Edna Greene; Frost, Jami Bice

    1999-01-01

    Considers how teachers engage children in character education and analyzes core values in books winning the Scott O'Dell Historical Fiction Award. Finds that these books are rich sources for examples of core values that are common features of character-education programs. Observes many teachers using short stories and picture books to insert…

  17. Simulating Children's Retrieval Errors in Picture-Naming: A Test of Foygel and Dell's (2000) Semantic/Phonological Model of Speech Production

    ERIC Educational Resources Information Center

    Budd, Mary-Jane; Hanley, J. Richard; Griffiths, Yvonne

    2011-01-01

    This study investigated whether Foygel and Dell's (2000) interactive two-step model of speech production could simulate the number and type of errors made in picture-naming by 68 children of elementary-school age. Results showed that the model provided a satisfactory simulation of the mean error profile of children aged five, six, seven, eight and…

  18. Analysis of zenith tropospheric delay in tropical latitudes

    NASA Astrophysics Data System (ADS)

    Zablotskyj, Fedir; Zablotska, Alexandra

    2010-05-01

    The paper studies some peculiarities of the nature of zenith tropospheric delay in tropical latitudes. There are shown the values of dry and wet components of zenith tropospheric delay obtained by an integration of the radiosonde data at 9 stations: Guam, Seyshelles, Singapore, Pago Pago, Hilo, Koror, San Cristobal, San Juan and Belem. There were made 350 atmospheric models for the period from 11th to 20th of January, April, July and October 2008 at 0h and 12h UT (Universal Time). The quantities of the dry dd(aer) and wet dw(aer) components of zenith tropospheric delay were determined by means of the integration for each atmospheric model. Then the quantities of the dry dd(SA), dd(HO) and wet dw(SA), dw(HO) components of zenith tropospheric delay (Saastamoinen and Hopfield analytical models) were calculated by the surface values of the pressure P0, temperature t0, relative air humidity U0 on the height H0 and by the geographic latitude φ. It must be point out the following from the analysis of the averaged quantities and differences δdd(SA), δdd(HO), δdw(SA), δdw(HO) between the correspondent components of zenith tropospheric delay obtained by the radiosonde data and by the analytical models: zenith tropospheric delay obtained by the radiosonde data amounts to considerably larger value in the equatorial zone, especially, at the expense of the wet component, in contrast to high and middle latitudes. Thus, the dry component of zenith tropospheric delay is equal at the average 2290 mm and the wet component is 290 mm; by the results of the analysis of Saastamoinen and Hopfield models the dry component differences δdd(SA) and δdd(HO) are negative in all cases and average -20 mm. It is not typical neither for high latitudes nor for middle ones; the differences between the values of the wet components obtained from radiosonde data and of Saastamoinen and Hopfield models are positive in general. Therewith the δdw(HO) values are larger than the correspondent

  19. Status of High Latitude Precipitation Estimates from Observations and Reanalyses

    NASA Technical Reports Server (NTRS)

    Behrangi, Ali; Christensen, Matthew; Richardson, Mark; Lebsock, Matthew; Stephens, Graeme; Huffman, George J.; Bolvin, David T.; Adler, Robert F.; Gardner, Alex; Lambrigtsen, Bjorn H.; hide

    2016-01-01

    An intercomparison of high-latitude precipitation characteristics from observation-based and reanalysis products is performed. In particular, the precipitation products from CloudSat provide an independent assessment to other widely used products, these being the observationally based Global Precipitation Climatology Project (GPCP), Global Precipitation Climatology Centre, and Climate Prediction Center Merged Analysis of Precipitation (CMAP) products and the ERA-Interim, Modern-Era Retrospective Analysis for Research and Applications (MERRA), and National Centers for Environmental Prediction-Department of Energy Reanalysis 2 (NCEP-DOE R2) reanalyses. Seasonal and annual total precipitation in both hemispheres poleward of 55 latitude are considered in all products, and CloudSat is used to assess intensity and frequency of precipitation occurrence by phase, defined as rain, snow, or mixed phase. Furthermore, an independent estimate of snow accumulation during the cold season was calculated from the Gravity Recovery and Climate Experiment. The intercomparison is performed for the 20072010 period when CloudSat was fully operational. It is found that ERA-Interim and MERRA are broadly similar, agreeing more closely with CloudSat over oceans. ERA-Interim also agrees well with CloudSat estimates of snowfall over Antarctica where total snowfall from GPCP and CloudSat is almost identical. A number of disagreements on regional or seasonal scales are identified: CMAP reports much lower ocean precipitation relative to other products, NCEP-DOE R2 reports much higher summer precipitation over Northern Hemisphere land, GPCP reports much higher snowfall over Eurasia, and CloudSat overestimates precipitation over Greenland, likely due to mischaracterization of rain and mixed-phase precipitation. These outliers are likely unrealistic for these specific regions and time periods. These estimates from observations and reanalyses provide useful insights for diagnostic assessment of

  20. ChaMPlane Galactic Bulge Latitude Survey: Optical Results

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Grindlay, J.; Hong, J.; Servillat, M.; van den Berg, M.; Laycock, S.

    2010-03-01

    We present the initial optical result of the Galactic Bulge Latitude Survey (BLS), which is an important component of our ChaMPlane survey (see Grindlay et al.). It extends from +/- 0.2 to +/- 1.5 degrees along the galactic latitude, centered at the SgrA*. The main goal is to measure the radial gradient of the Lx > 1031.5 erg/s source population (primarily CVs and qLMXBs) along latitude vs. longitude in the galactic bulge. We completed the BLS survey in Chandra cycles 7-10, with 36 ACIS-I pointings of 15ks each (see Hong et al.). The survey covers two 1.2 square-degrees region in the "north" (BLS-N) and "south" (BLS-S) of the galactic plane. The southern tip of the BLS-S is connected with our Chandra observation "Limiting Window", a low extinction window closest to the SgrA* with Av=3.9. We also completed the corresponding optical and IR (see van den Berg et al.) survey to cover the same region. The optical images (V,R,I,H-alpha band) were obtained from CTIO/4m/Mosaic from 2008 to 2009. Six Mosaic images (36'x36') covers all 36 Chandra pointings. Candidate optical counterparts of the X-ray point sources were found from the Mosaic images. Although, due to severe extinction towards the galactic center, most of the real counterparts are in the foreground of the bulge, except in the southern tip of the BLS-S. Spectroscopic follow-ups for the identified optical counterparts were conducted in 2009 using the CTIO/4m/Hydra for classification, to identify the nature of the Chandra sources.

  1. Storm time heavy ion outflow at mid-latitudes

    SciTech Connect

    Yeh, H.C.; Foster, J.C. )

    1990-06-01

    Local ionospheric observations with the Millstone Hill incoherent scatterradar reveal an upward ion bulk velocity in excess of 3 km s{sup {minus} 1} at 1,000 km altitude during the very large magnetic storm on February 8, 1986. The upward flux of O{sup +} ions exceeded 3 {times} 10{sup 9} cm{sup {minus}2} s{sup {minus}1} at 42{degree} geodetic latitude (55{degree} {Lambda}) for a 3-hour period around 18 MLT during the event. Frictinal ion heating with ion temperatures in excess of 4,000 K at 500 km altitude was observed by the radar in the vicinity of the ion outflow event. Satellite observations place the ion outflow event within a region of intense ion and electron precipitation on field lines associated with the storm-perturbed ring current. For a one-dimensional analysis of the observed plasma profiles, continuity considerations indicate a region of intense O{sup +} production (200 cm{sup {minus}3} s{sup {minus}1}) as well as significant upward acceleration (5-10 m s{sup {minus}2}) in the region between 600 km and 800 km altitude where the outflow approaches supersonic speed. Ionizing collisions involving fast backsplash neutral O atoms (Torr et al., 1974) produced by ring current heavy ion precipitation can provide sufficient upward momentum to account for the acceleration in the observed outflowing thermal O{sup +} fluxes. Alternatively, the outflow event can be explained in terms of a time-dependent diffusion process triggered by a sudden change in the frictional heating rate in the collision-dominated F region (St.-Maurice, 1989). The concurrence of rapid ion convection and energetic ring current precipitation is unique at mid-latitudes during intense magnetic storms. Under these conditions, the observations indicate that the mid-latitude ionosphere constitutes a significant source of upflowing thermal O{sup +} fluxes to the overlying magnetosphere.

  2. Ionospheric signatures of cusp latitude Pc 3 pulsations

    SciTech Connect

    Engebretson, M.J.; Anderson, B.J. ); Cahill, L.J. Jr. ); Arnoldy, R.L. ); Rosenberg, T.J. ); Carpenter, D.L. ); Gail, W.B. ); Eather, R.H. )

    1990-03-01

    The authors have compared search coil magnetometer, riometer, photometer, and ELF-VLF receiver data obtained at South Pole Station and McMurdo, Antarctica, during selected days in March and April 1986. Narrow-band magnetic pulsations in the Pc 3 period range are observed simultaneously at both stations in the dayside sector during times of low interplanetary magnetic field (IMF) cone angle, but are considerably stronger at South Pole, which is located at a latitude near the nominal foot point of the daysie cusp/cleft region. Pulsations in auroral light a 427.8 nm wavelength are often observed with magnetic pulsations at South Pole, but such optical pulsations are not observed at McMurdo. When Pc 3 pulsations are present, they exhibit nearly identical frequencies, proportional to the magnitude of the IMF, in magnetometer, photometer, and ELF-VLF receiver signals at South Pole Station and in magnetometer signals at McMurdo. Singals from the 30-MHz riometer at South Pole are modulated in concert with the magnetic and optical variations during periods of broadband pulsation activity, but no riometer variations are noted during periods of narrow-band activity. Because riometers are sensitive to electrons of auroral energies (several keV and above), while the 427.8-nm photometer is sensitive to precipitation with much lower energies, they interpret these observatons as showing that precipitating magnetosheathlike electrons (with energies {le} 1 keV) at nominal dayside cleft latitudes are at times modulated with frequencies similar to those of upstream waves. They suggest that these particles may play an important role, via modification of ionospheric currents and conductivities, in the transmission of upstream wave signals into the magnetosphere and in the generation of dayside high-latitude Pc 3 pulsations.

  3. Low-latitude mountain glacier evidence for abrupt climate changes

    NASA Astrophysics Data System (ADS)

    Thompson, L. G.; Mosley-Thompson, E. S.; Lin, P.; Davis, M. E.; Mashiotta, T. A.; Brecher, H. H.

    2004-12-01

    Clear evidence that a widespread warming of Earth's climate system is now underway comes from low latitude mountain glaciers. Proxy temperature histories reconstructed from ice cores, and the rapidly accelerating loss of both the total ice area and ice volume on a near global scale suggest that these glaciers responding to increasing rates of melting. In situ observations reveal the startling rates at which many tropical glaciers are disappearing. For example, the retreat of the terminus of the Qori Kalis Glacier in Peru is roughly 200 meters per year, 40 times faster than its retreat rate in 1978. Similarly, in 1912 the ice on Mount Kilimanjaro covered 12.1 km2, but today it covers only 2.6 km2. If the current rate of retreat continues, the perennial ice fields may disappear within the next few decades, making this the first time in the past 11,700 years that Kilimanjaro will be devoid of the ice that shrouds its summit. Tropical glaciers may be considered ``the canaries in the coal mine'' for the global climate system as they integrate and respond to key climatological variables, such as temperature, precipitation, cloudiness, humidity, and incident solar radiation. A composite of the decadally-averaged oxygen isotopic records from three Andean and three Tibetan ice cores extending back over the last two millennia shows an isotopic enrichment in the 20th century that suggests a large-scale warming is underway at lower latitudes. Multiple lines of evidence from Africa, the Middle East, Europe and South America indicate an abrupt mid-Holocene climate event in the low latitudes. If such an event were to occur now with a global human population of 6.3 billion people, the consequences could be severe. Clearly, we need to understand the nature and cause of abrupt climate events.

  4. Thermospheric Density Model Including High-Latitude Energy Sources

    NASA Astrophysics Data System (ADS)

    Moe, O. K.; Moe, M. M.

    2006-12-01

    As was predicted long ago by Sydney Chapman, there is a major contribution to thermospheric energy from the magnetosphere at all times. The contribution of this magnetospheric energy source produces a neutral density bulge at high latitudes even during geomagnetically quiet times. We present an analytical, semi- empirical model of the global neutral density at such quiet times. The total density is expressed as the sum of two terms: The first term describes the combined effects of the solar ultra-violet heating and various other contributions like the semi-annual variation; the second term gives the contribution to the density associated with particle precipitation and joule heating coming from magnetospheric sources during times of low geomagnetic activity. The region of density enhancement at high latitudes is associated with the locations of the dayside cusps. Therefore the model produces a density distribution which depends on universal time as well as on altitude, latitude, local time, and the usual solar UV energy source. The numerical values of the parameters in the empirical model were originally determined 30 years ago from density data collected by the Bell-MESA accelerometer on the LOGACS satellite and the pressure gauge on the SPADES satellite. As an example of the model output, we show a Mercator projection of the global density distribution at 400 km altitude at 12 hours GMT in late May at a time of moderate solar activity and low geomagnetic activity. The parameters in the model can now be substantially improved by using recent advances like the latest description of the semi-annual variation and by incorporating the precise density measurements made by the accelerometers on board the CHAMP and GRACE satellites. In the original model, density values at times of high geomagnetic activity were included in the second density term. The parameters in that term can also be improved as accurate storm-time densities become available.

  5. [Total Elbow Replacement - Implantation of the Latitude Prosthesis (Tornier)].

    PubMed

    Hackl, M; Wegmann, K; Leschinger, T; Ries, C; Burkhart, K J; Müller, L

    2015-10-01

    Due to technical progress, the indication for total elbow arthroplasty could be expanded in recent years. As a result, the demand regarding functionality and mobility of the replaced joint has risen as well. Elbow arthroplasty has to be considered as technically demanding. Only with detailed knowledge of this surgical procedure and its possible intraoperative pitfalls can one provide the best possible results. In this instructional video we explain the implantation of the Latitude elbow prosthesis (Tornier) putting emphasis on the correct approach as well as implantation of the prosthesis and subsequent wound closure.

  6. How Altitude and Latitude Control Dune Morphometry on Titan

    NASA Technical Reports Server (NTRS)

    Le Gall, A.; Hayes, A.; Ewing, R.; Janssen, M. A.; Radebaugh, J.; Savage, C.; Encrenaz, P.

    2011-01-01

    Dune fields are one of the dominant landforms and represent the largest known organic reservoir on Titan. SAR-derived topography show that Titan's dune terrains tend to occupy the lowest altitude areas in equatorial regions occurring at mean elevations between approx.-400 and 0 m. In elevated dune terrains, there is a definite trend towards a smaller dune to interdune ratio, interpreted as due to limited sediment availability. A similar linear correlation is observed with latitude, suggesting that the quantity of windblown sand in the dune fields tends to decrease as one moves farther north. These findings place important constraints on Titan's geology and climate.

  7. High latitude helical surge of May 22, 1989

    NASA Astrophysics Data System (ADS)

    Okten, Adnan; Cakmak, Hikmet

    1990-08-01

    A helical surge (S 72, W 90) was recorded by a monochromatic filter at the University Observatory of Istanbul. It is a significant one at a very high latitude and without any center of activity. A sequence of the filtergrams showed some condensed points from which the motions of the plasma are traced. Different velocities were determined on each of the branches of the helical surge during its evolution. The surge reached its maximum height of 298,000 km, and the maximum velocity of this upper region was 250 km/s.

  8. Anomalous astronomical time-latitude residuals: a potential earthquake precursor

    NASA Astrophysics Data System (ADS)

    Hu, Hui; Su, You-Jin; Gao, Yi-Fei; Wang, Rui

    2016-09-01

    The geophysical mechanism behind astronomical time-latitude residuals (ATLR) are discussed. The photoelectric astrolabe at Yunnan Observatory (YO) observed apparent synchronous anomalous ATLR before the Wenchuan M8.0 earthquake (EQ) in May 12, 2008 and the Lushan M7.0 EQ n April 20, 2013. We compared the ATLR from the YO photoelectric astrolabe and EQ data since 1976. Anomalous ATLR was observed before several strong EQs in the Yunnan Province. We believe the photoelectric astrolabe can be used to predict strong EQs and the anomalous ATLR are a potential EQ precursor.

  9. Double-peaked sodium layers at high latitudes

    NASA Technical Reports Server (NTRS)

    Von Zahn, U.; Goldberg, R. A.; Stegman, J.; Witt, G.

    1989-01-01

    Na lidar observations indicate that at high latitudes in summer the neutral Na layer frequently attains a double-peaked structure. The main layer with a maximum near 90 km altitude is supplemented by a secondary, narrow layer near 95 km altitude. Results are presented concerning secondary sodium layers. It appears likely that the formation of secondary Na layers observed frequently above the lidar site is not solely a 'sodium phenomenon', but part of a more comprehensive layering process for metal atoms and ions. Na(+)/Na density ratios close to 0.5 near the peaks of both the main and secondary layers are derived.

  10. High Latitude Gravity Wave Forcing by the Disturbed Polar Vortex

    NASA Astrophysics Data System (ADS)

    Mehta, D.; Gerrard, A. J.; Ebihara, Y.; Weatherwax, A. T.

    2015-12-01

    We present mesopause gravity wave observations from 589-nm Na all-sky data taken by a multiwavelength all-sky imager located at South Pole, Antarctica. Focusing on gravity waves observed during the 2003 and 2004 austral winter seasons, we investigate possible sources of observed waves using linear gravity wave ray-tracing. By comparing wave ray paths with the structure of the polar vortex obtained from the ECMWF operational model, we show that a unique generator of gravity waves that then propagate into the high latitude mesospause is the disturbance of the polar vortex near 40-km altitude due to the formation of baroclinic instabilities.

  11. Computer model of high-latitude scintillation. [WBMOD program

    SciTech Connect

    Fremouw, E.J.

    1982-01-01

    The DNA Wideband satellite experiment provided extensive data on scintillation produced in high-altitude structured plasmas. A computer program, WBMOD, is being developed to summarize those data in an applications-oriented way. The program contains the phase-screen scattering theory of Rino and a morphological description of ionospheric irregularities (thus far only at auroral latitudes) based on Wideband observations. It permits a user to compute scintillation indices for both phase and intensity as a function of system operating parameters and solar-ionospheric disturbance level. Correction is made for multiple scatter, and the user may choose either one-way (communication) or two-way (radar) propagation.

  12. Pathways of high-latitude dust in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Baddock, Matthew C.; Mockford, Tom; Bullard, Joanna E.; Thorsteinsson, Throstur

    2017-02-01

    The contribution of mineral dust from high-latitude sources has remained an under-examined feature of the global dust cycle. Dust events originating at high latitudes can provide inputs of aeolian sediment to regions lying well outside the subtropical dust belt. Constraining the seasonal variability and preferential pathways of dust from high-latitude sources is important for understanding the potential impacts that the dust may have on wider environmental systems, such as nearby marine or cryospheric domains. This study quantifies dust pathways from two areas exhibiting different emission dynamics in the north and south of Iceland, which is a prominent Northern Hemisphere dust source. The analysis uses air parcel trajectory modelling, and for the first time for high-latitude sources, explicitly links all trajectory simulations to time-specific (meteorological) observations of suspended dust. This approach maximises the potential for trajectories to represent dust, and illustrates that trajectory climatologies not limited to dust can grossly overestimate the potential for dust transport. Preferential pathways emerge that demonstrate the role of Iceland in supplying dust to the Northern Atlantic and sub-Arctic oceans. For dust emitted from northern sources, a dominant route exists to the northeast, into the Norwegian, Greenland and Barents Seas, although there is also potential for delivery to the North Atlantic in summer months. From the southern sources, the primary pathway extends into the North Atlantic, with a high density of trajectories extending as far south as 50°N, particularly in spring and summer. Common to both southern and northern sources is a pathway to the west-southwest of Iceland into the Denmark Strait and towards Greenland. For trajectories simulated at ≤500 m, the vertical development of dust plumes from Iceland is limited, likely due to the stable air masses of the region suppressing the potential for vertical motion. Trajectories rarely

  13. High-latitude dayside electric field and particle measurements

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.; Johnstone, A. D.

    1973-01-01

    Two rockets carrying electric field and low energy particle instrumentation were launched near noon at 80 deg magnetic latitude. One flight encountered polar cap conditions only while the other traversed part of the polar cusp. Although weak particle precipitation was measured on both flights, bursts of intense magnetosheath-type electron fluxes were detected on the latter. Strong electric fields such as would result from anti-sunward convection were observed during both flights. The measurements are compared with results obtained by other types of space craft and interpreted in the light of those data.

  14. Enhanced mid-latitude tropospheric warming in satellite measurements.

    PubMed

    Fu, Qiang; Johanson, Celeste M; Wallace, John M; Reichler, Thomas

    2006-05-26

    The spatial distribution of tropospheric and stratospheric temperature trends for 1979 to 2005 was examined, based on radiances from satellite-borne microwave sounding units that were processed with state-of-the-art retrieval algorithms. We found that relative to the global-mean trends of the respective layers, both hemispheres have experienced enhanced tropospheric warming and stratospheric cooling in the 15 to 45 degrees latitude belt, which is a pattern indicative of a widening of the tropical circulation and a poleward shift of the tropospheric jet streams and their associated subtropical dry zones. This distinctive spatial pattern in the trends appears to be a robust feature of this 27-year record.

  15. A computer model of high-latitude scintillation

    NASA Astrophysics Data System (ADS)

    Fremouw, E. J.

    1982-01-01

    The DNA Wideband satellite experiment provided extensive data on scintillation produced in high-altitude structured plasmas. A computer program, WBMOD, is being developed to summarize those data in an applications-oriented way. The program contains the phase-screen scattering theory of Rino and a morphological description of ionospheric irregularities (thus far only at auroral latitudes) based on Wideband observations. It permits a user to compute scintillation indices for both phase and intensity as a function of system operating parameters and solar-ionospheric disturbance level. Correction is made for multiple scatter, and the user may choose either one-way (communication) or two-way (radar) propagation.

  16. Planetary radio emissions from low magnetic latitudes - Observations and theories

    NASA Astrophysics Data System (ADS)

    Jones, Dyfrig

    Recent observations of planetary radiations from low magnetic latitudes are reviewed. At Earth a major source of nonthermal continuum is Terrestrial Myriametric Radiation (TMR) from the equatorial plasmapause and from the magnetopause. The theories proposed for the production of TMR are listed and their predictions are compared with satellite observations. The application of the theories to Jovian Kilometric Radiation (KOM), the radio emission at Jupiter which has been suggested to be the analogue of TMR, is reviewed. The implications of the TMR and KOM results for radiations observed at Saturn and Uranus are briefly considered.

  17. Contrast and latitude of CT hard copy: an ROC study.

    PubMed

    Warren, R C

    1981-10-01

    A decision between film and paper for CT hard copy must be based on the different latitudes of the two media. The author conducted a receiver operating characteristic (ROC) analysis in which image information was matched to the characteristics of the recording media by adjusting both the window width of the display and the monitor contrast. Under these conditions, film images were found to be superior to print images for detection of noise-limited features. It is proposed that if the same optimization procedure were applied to clinical CT scans, the information content of the images could be increased.

  18. Double-peaked sodium layers at high latitudes

    NASA Technical Reports Server (NTRS)

    Von Zahn, U.; Goldberg, R. A.; Stegman, J.; Witt, G.

    1989-01-01

    Na lidar observations indicate that at high latitudes in summer the neutral Na layer frequently attains a double-peaked structure. The main layer with a maximum near 90 km altitude is supplemented by a secondary, narrow layer near 95 km altitude. Results are presented concerning secondary sodium layers. It appears likely that the formation of secondary Na layers observed frequently above the lidar site is not solely a 'sodium phenomenon', but part of a more comprehensive layering process for metal atoms and ions. Na(+)/Na density ratios close to 0.5 near the peaks of both the main and secondary layers are derived.

  19. A new high-latitude low-surface brightness SNR

    NASA Astrophysics Data System (ADS)

    Reich, P.; Kothes, R.; Foster, T.; Reich, W.

    2016-06-01

    We have discovered a new SNR in the Galactic Anticentre at a Galactic latitude of about 10 degrees with the DRAO synthesis telescope at 21-cm. Here we report on follow-up Effelsberg observations at 6-cm. This shell-type SNR is almost circular with a diameter of about 1.5 degrees. Its radio surface brightness is extremely low and it is highly linearly polarized. High-velocity HI-gas from the anti-centre shell seems associated, which places the SNR at a distance between 0.5 kpc and 2.5 kpc.

  20. A survey of formaldehyde in high Galactic latitudes

    NASA Technical Reports Server (NTRS)

    Heithausen, A.; Mebold, U.; De Vries, H. W.

    1987-01-01

    The discovery of formaldehyde (H2CO) in four out of 15 CO-clouds observed in high Galactic latitudes is reported. For one of these a velocity-integrated formaldehyde map is presented. The clouds are clearly connected to CO clouds described by de Vries et al. (1986), to Lynds bright and dark nebulae (Lynds, 1963), and to the Galactic infrared cirrus (Low et al., 1984). The distribution of CO and H2CO clouds is compared. The depths of the l(10-11)H2CO lines show no correlation to the integrated J = l-0(C-12)O line intensities.

  1. The brightest high-latitude 12-micron IRAS sources

    NASA Technical Reports Server (NTRS)

    Hacking, P.; Beichman, C.; Chester, T.; Neugebauer, G.; Emerson, J.

    1985-01-01

    The Infrared Astronomical Satellite (IRAS) Point Source catalog was searched for sources brighter than 28 Jy (0 mag) at 12 microns with absolute galactic latitude greater than 30 deg excluding the Large Magellanic Cloud. The search resulted in 269 sources, two of which are the galaxies NGC 1068 and M82. The remaining 267 sources are identified with, or have infrared color indices consistent with late-type stars some of which show evidence of circumstellar dust shells. Seven sources are previously uncataloged stars. K and M stars without circumstellar dust shells, M stars with circumstellar dust shells, and carbon stars occupy well-defined regions of infrared color-color diagrams.

  2. Neutral winds above 200Km at high latitudes

    NASA Technical Reports Server (NTRS)

    Meriwether, J. W.; Heppner, J. P.; Stolarik, J. D.; Wescott, E. M.

    1972-01-01

    Motion from multiple chemical releases between 200 and 300 km from 15 rockets launched from 4 high latitude locations are analyzed. The observations in the evening and midnight hours at magnetic altitudes or = 65 deg suggest that in these regions ion drag is the dominant force in driving neutral winds between 200 and 300 km. This conclusion is based on both the agreement between ion and neutral drift directions, and the fact that there are distinct changes in the wind associated with (a) the reversal in east-west ion drift at the Harang discontinuity, and (b) the transition from auroral belt, sunward ion drift and polar cap, anti-solar ion drift.

  3. Ionospheric storm effects at subauroral latitudes - A case study

    NASA Technical Reports Server (NTRS)

    Proelss, G. W.; Brace, L. H.; Mayr, H. G.; Carignan, G. R.; Killeen, T. L.

    1991-01-01

    An attempt is made to classify ionospheric storm effects at subauroral latitudes according to their presumed origin. The storm of December 7/8, 1982, serves as an example. It is investigated using ionosonde, electron content, and DE 2 satellite data. The following effects are distinguished: (1) positive storm effects caused by traveling atmospheric disturbances, (2) positive storm effects caused by changes in the large-scale thermospheric wind circulation, (3) positive storm effects caused by the expansion of the polar ionization enhancement, (4) negative storm effects caused by perturbations of the neutral gas composition, and (5) negative storm effects caused by the equatorward displacement of the trough region.

  4. Ionospheric storm effects at subauroral latitudes: A case study

    SciTech Connect

    Proelss, G.W. ); Brace, L.H.; Mayr, H.G. ); Carignan, G.R.; Killeen, T.L. ); Klobuchar, J.A. )

    1991-02-01

    An attempt is made to classify ionospheric storm effects at subauroral latitudes according to their presumed origin. The storm of December 7/8, 1982, serves as an example. It is investigated using ionosonde, electron content, and DE 2 satellite data. The following effects are distinguished: (1) positive storm effects caused by traveling atmospheric disturbances, (2) positive storm effects caused by changes in the large-scale thermospheric wind circulation, (3) positive storm effects caused by the expansion of the polar ionization enhancement, (4) negative storm effects caused by perturbations of the neutral gas composition, and (5) negative storm effects caused by the equatorward displacement of the trough region.

  5. Analysis of star pair latitudes. [for polar motion

    NASA Technical Reports Server (NTRS)

    Graber, M. A.

    1979-01-01

    Star pair latitude observations form the basis for the pole positions reported by the International Polar Motion Service (IMPS). The IPMS processes these observations to produce a mean pole position. However, the time series of observations contains high-frequency information which is lost in the calculation of the mean pole. In this study, 2931 star pair observations are analyzed. A possible large excitation at one cycle per solar day is observed. The average power level in the frequency band of the tesseral tides is seen to be high, although the peaks cannot be conclusively identified as tidal phenomena.

  6. Ionospheric storm effects at subauroral latitudes - A case study

    NASA Technical Reports Server (NTRS)

    Proelss, G. W.; Brace, L. H.; Mayr, H. G.; Carignan, G. R.; Killeen, T. L.

    1991-01-01

    An attempt is made to classify ionospheric storm effects at subauroral latitudes according to their presumed origin. The storm of December 7/8, 1982, serves as an example. It is investigated using ionosonde, electron content, and DE 2 satellite data. The following effects are distinguished: (1) positive storm effects caused by traveling atmospheric disturbances, (2) positive storm effects caused by changes in the large-scale thermospheric wind circulation, (3) positive storm effects caused by the expansion of the polar ionization enhancement, (4) negative storm effects caused by perturbations of the neutral gas composition, and (5) negative storm effects caused by the equatorward displacement of the trough region.

  7. Ulysses solar wind plasma observations from peak southerly latitude through perihelion and beyond

    SciTech Connect

    Phillips, J.L.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; McComas, D.J.; Goldstein, B.E.; Neugebauer, M.; Hammond, C.M.

    1995-09-01

    We present Ulysses solar wind plasma data from the peak southerly latitude of {minus}80.2{degrees} through +64.9{degrees} latitude on June 7, 1995. Ulysses encountered fast wind throughout this time except for a 43{degrees} band centered on the solar equator. Median mass flux was nearly constant with latitude, while speed and density had positive and negative poleward gradients, respectively. Solar wind momentum flux was highest at high latitudes, suggesting a latitudinal asymmetry in the heliopause cross section. Solar wind energy flux density was also highest at high latitudes.

  8. Ulysses solar wind plasma observations from peak southerly latitude through perihelion and beyond

    SciTech Connect

    Phillips, J.L.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; McComas, D.J.; Goldstein, B.E.; Neugebauer, M.; Hammond, C.M.

    1996-07-01

    We present Ulysses solar wind plasma data from the peak southerly latitude of {minus}80.2{degree} through +64.9{degree} latitude on June 7, 1995. Ulysses encountered fast wind throughout this time except for a 43{degree} equatorial band. Mass flux was nearly constant with latitude, while speed (density) had positive (negative) poleward gradients. Momentum flux was highest at high latitudes, suggesting a latitudinal asymmetry in the heliopause cross section. Solar wind energy flux density was also highest at high latitudes. {copyright} {ital 1996 American Institute of Physics.}

  9. Can evolutionary constraints explain the rarity of nitrogen-fixing trees in high-latitude forests?

    PubMed

    Menge, Duncan N L; Crews, Timothy E

    2016-09-01

    Contents 1195 I. 1195 II. 1196 III. 1196 IV. 1200 1200 References 1200 SUMMARY: The rarity of symbiotic nitrogen (N)-fixing trees in temperate and boreal ('high-latitude') forests is curious. One explanation - the evolutionary constraints hypothesis - posits that high-latitude N-fixing trees are rare because few have evolved. Here, we consider traits necessary for high-latitude N-fixing trees. We then use recent developments in trait evolution to estimate that > 2000 and > 500 species could have evolved from low-latitude N-fixing trees and high-latitude N-fixing herbs, respectively. Evolution of N-fixing from nonfixing trees is an unlikely source of diversity. Dispersal limitation seems unlikely to limit high-latitude N-fixer diversity. The greater number of N-fixing species predicted to evolve than currently inhabit high-latitude forests suggests a greater role for ecological than evolutionary constraints.

  10. Map of Martian Potassium at Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element potassium. Potassium, having the chemical symbol K, is a naturally radioactive element and is a minor constituent of rocks on the surface of both Mars and Earth. The region of highest potassium content, shown in red, is concentrated in the northern part of Acidalia Planitia (centered near 55 degrees N, -30 degrees). Several areas of low potassium content, shown in blue, are distributed across the mid-latitudes, with two significant low concentrations, one associated with the Hellas Basin (centered near 35 degrees S, 70 degrees) and the other lying southeast of Elysium Mons (centered near 10 degrees N, 160 degrees). Contours of constant surface elevation are also shown. The long continuous line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, is the prime contractor for the 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.

  11. Structure of High Latitude Currents in Magnetosphere-Ionosphere Models

    NASA Astrophysics Data System (ADS)

    Wiltberger, M.; Rigler, E. J.; Merkin, V.; Lyon, J. G.

    2017-03-01

    Using three resolutions of the Lyon-Fedder-Mobarry global magnetosphere-ionosphere model (LFM) and the Weimer 2005 empirical model we examine the structure of the high latitude field-aligned current patterns. Each resolution was run for the entire Whole Heliosphere Interval which contained two high speed solar wind streams and modest interplanetary magnetic field strengths. Average states of the field-aligned current (FAC) patterns for 8 interplanetary magnetic field clock angle directions are computed using data from these runs. Generally speaking the patterns obtained agree well with results obtained from the Weimer 2005 computing using the solar wind and IMF conditions that correspond to each bin. As the simulation resolution increases the currents become more intense and narrow. A machine learning analysis of the FAC patterns shows that the ratio of Region 1 (R1) to Region 2 (R2) currents decreases as the simulation resolution increases. This brings the simulation results into better agreement with observational predictions and the Weimer 2005 model results. The increase in R2 current strengths also results in the cross polar cap potential (CPCP) pattern being concentrated in higher latitudes. Current-voltage relationships between the R1 and CPCP are quite similar at the higher resolution indicating the simulation is converging on a common solution. We conclude that LFM simulations are capable of reproducing the statistical features of FAC patterns.

  12. Naturally occurring allele diversity allows potato cultivation in northern latitudes.

    PubMed

    Kloosterman, Bjorn; Abelenda, José A; Gomez, María del Mar Carretero; Oortwijn, Marian; de Boer, Jan M; Kowitwanich, Krissana; Horvath, Beatrix M; van Eck, Herman J; Smaczniak, Cezary; Prat, Salomé; Visser, Richard G F; Bachem, Christian W B

    2013-03-14

    Potato (Solanum tuberosum L.) originates from the Andes and evolved short-day-dependent tuber formation as a vegetative propagation strategy. Here we describe the identification of a central regulator underlying a major-effect quantitative trait locus for plant maturity and initiation of tuber development. We show that this gene belongs to the family of DOF (DNA-binding with one finger) transcription factors and regulates tuberization and plant life cycle length, by acting as a mediator between the circadian clock and the StSP6A mobile tuberization signal. We also show that natural allelic variants evade post-translational light regulation, allowing cultivation outside the geographical centre of origin of potato. Potato is a member of the Solanaceae family and is one of the world's most important food crops. This annual plant originates from the Andean regions of South America. Potato develops tubers from underground stems called stolons. Its equatorial origin makes potato essentially short-day dependent for tuberization and potato will not make tubers in the long-day conditions of spring and summer in the northern latitudes. When introduced in temperate zones, wild material will form tubers in the course of the autumnal shortening of day-length. Thus, one of the first selected traits in potato leading to a European potato type is likely to have been long-day acclimation for tuberization. Potato breeders can exploit the naturally occurring variation in tuberization onset and life cycle length, allowing varietal breeding for different latitudes, harvest times and markets.

  13. Comparison of mesospheric sodium layers at different latitudes

    NASA Astrophysics Data System (ADS)

    Liu, Yingjie

    With the support of the Chinese Meridional project in the eastern hemisphere, two brand new sodium fluorescence lidars with the same configuration were respectively set up at Yanqing (40.46(°) N, 115.98(°) E) and Haikou (20.04(°) N, 110.34(°) E) in April, 2010. Based on the observations obtained from 2010 to 2012, comparison of the Na layer at these two latitudes was performed. It reveals a strong correlation in the topside layer between these two sites. Independently of their seasonal characteristics at lower altitudes, they both show an extension to 120 km and above, predominantly during summer. Simultaneous observations at these two sites show that the correlation above 102 km is remarkable in contrast to their different seasonal characteristics below 98 km. It indicates that different processes dominate different height ranges in the Na layer. Meanwhile, it indicates that the topside extension effect is global, combined with the observations at other latitudes. Besides, when the topside layer has an extension, the bottom side layer extends slightly downward, too. Comparison with known meteor showers shows that most of these extensions correspond well to one or more meteor showers, although not one by one. Meteor showers with velocities less than 35 km/s appear to have more influence on these extensions.

  14. {sup 36}Cl bomb fallout at mid latitudes

    SciTech Connect

    Synal, H.A.; Beer, J.; Gaeggeler, H.

    1995-12-01

    Large amounts of {sup 36}Cl have been produced during the atmospheric test of nuclear weapons in the late fifties and early sixties. During this time the {sup 36}Cl fallout was about three orders of magnitudes larger than during previous times. The well defined {sup 36}Cl pulse has a great potential for hydrological investigations, especially as a tracer for groundwater studies. Detailed measurements of bomb produced {sup 36}Cl were carried out earlier on ice cores from Dye-3 (Greenland). To adopt the {sup 36}Cl pulse measured in Greenland as an input function to other locations its latitude dependence has to be known. So far, atmospheric transport models and the measured distribution of {sup 90}Sr and {sup 137}Cs fallout are used to estimate the latitude dependence of meteoric and bomb produced {sup 36}Cl fallout. In this contribution, {sup 36}Cl measurements on an ice core from an Alpine Glacier (Fiescher Horn, Switzerland) are presented. The results are compared with earlier measurements from a Greenland ice core and implications for the global {sup 36}Cl transport are discussed.

  15. Evapotranspiration Cycles in a High Latitude Agroecosystem: Potential Warming Role

    PubMed Central

    Ruairuen, Watcharee

    2015-01-01

    As the acreages of agricultural lands increase, changes in surface energetics and evapotranspiration (ET) rates may arise consequently affecting regional climate regimes. The objective of this study was to evaluate summertime ET dynamics and surface energy processes in a subarctic agricultural farm in Interior Alaska. The study includes micrometeorological and hydrological data. Results covering the period from June to September 2012 and 2013 indicated consistent energy fractions: LE/Rnet (67%), G/Rnet (6%), H/Rnet (27%) where LE is latent heat flux, Rnet is the surface net radiation, G is ground heat flux and H is the sensible heat flux. Additionally actual surface evapotranspiration from potential evaporation was found to be in the range of 59 to 66%. After comparing these rates with those of most prominent high latitude ecosystems it is argued here that if agroecosystem in high latitudes become an emerging feature in the land-use, the regional surface energy balance will significantly shift in comparison to existing Arctic natural ecosystems. PMID:26368123

  16. Latitude delineates patterns of biogeography in terrestrial Streptomyces.

    PubMed

    Choudoir, Mallory J; Doroghazi, James R; Buckley, Daniel H

    2016-12-01

    The biogeography of Streptomyces was examined at regional spatial scales to identify factors that govern patterns of microbial diversity. Streptomyces are spore forming filamentous bacteria which are widespread in soil. Streptomyces strains were isolated from perennial grass habitats sampled across a spatial scale of more than 6000 km. Previous analysis of this geographically explicit culture collection provided evidence for a latitudinal diversity gradient in Streptomyces species. Here the hypothesis that this latitudinal diversity gradient is a result of evolutionary dynamics associated with historical demographic processes was evaluated. Historical demographic phenomena have genetic consequences that can be evaluated through analysis of population genetics. Population genetic approaches were applied to analyze population structure in six of the most numerically abundant and geographically widespread Streptomyces phylogroups from our culture collection. Streptomyces population structure varied at regional spatial scales, and allelic diversity correlated with geographic distance. In addition, allelic diversity and gene flow are partitioned by latitude. Finally, it was found that nucleotide diversity within phylogroups was negatively correlated with latitude. These results indicate that phylogroup diversification is constrained by dispersal limitation at regional spatial scales, and they are consistent with the hypothesis that historical demographic processes have influenced the contemporary biogeography of Streptomyces.

  17. Structure of high latitude currents in magnetosphere-ionosphere models

    NASA Astrophysics Data System (ADS)

    Wiltberger, M. J.; Lyon, J.; Merkin, V. G.; Rigler, E. J.

    2016-12-01

    Using three resolutions of the Lyon-Fedder-Mobarry global magnetosphere-ionosphere model (LFM) and the Weimer 2005 empirical model the structure of the high latitude field-aligned current patterns is examined. Each LFM resolution was run for the entire Whole Heliosphere Interval (WHI), which contained two high-speed solar wind streams and modest interplanetary magnetic field strengths. Average states of the field-aligned current (FAC) patterns for 8 interplanetary magnetic field clock angle directions are computed using data from these runs. Generally speaking the patterns obtained agree well with results from the Weimer 2005 computed using the solar wind and IMF conditions that correspond to each bin. As the simulation resolution increases the currents become more intense and confined. A machine learning analysis of the FAC patterns shows that the ratio of Region 1 (R1) to Region 2 (R2) currents decreases as the simulation resolution increases. This brings the simulation results into better agreement with observational predictions and the Weimer 2005 model results. The increase in R2 current strengths in the model also results in a better shielding of mid- and low-latitude ionosphere from the polar cap convection, also in agreement with observations. Current-voltage relationships between the R1 strength and the cross-polar cap potential (CPCP) are quite similar at the higher resolutions indicating the simulation is converging on a common solution. We conclude that LFM simulations are capable of reproducing the statistical features of FAC patterns.

  18. The Low-latitude Ionospheric Sensor Network: The Initial Campaigns

    NASA Astrophysics Data System (ADS)

    Doherty, P. H.; Valladares, C. E.; Carrano, C.

    2009-05-01

    The Low-latitude Ionospheric Sensor Network (LISN) is a distributed observatory designed to provide regional coverage in South America and high-temporal resolution measurements to diagnose the initiation and development of plasma structures and the state and dynamics of the low latitude ionosphere. It combines inexpensive GPS receivers and state-of-the-art radars such as the Vertical Incidence Pulsed Ionospheric Radar (VIPIR) ionosondes and magnetometers. This paper describes the characteristics of the LISN distributed observatory and discusses the results of the first two campaigns. LISN will be comprised of nearly 70 GPS receivers with the capability to measure Total Electron Content (TEC), amplitude and phase scintillation and Traveling Ionospheric Disturbances (TIDs). LISN will also include 5 ionosondes able to measure nighttime E-region densities and 5 collocated magnetometers that will be placed along the same magnetic meridian. The first campaign was dedicated to detect medium-scale (~100 km) TIDs and was conducted at Huancayo, Peru in July 2008 using 3 GPS receivers spaced by 4-5 km arranged in a triangular configuration. TEC data corresponding to 3 consecutive days indicate that the TIDs phase velocity was close to 120 m/s and directed northward during the early evening hours. The second campaign was conducted in February 2009 using 3 GPS receivers installed near Ancon and coordinated with the VIPIR ionosonde running in an interferometer mode. We will discuss the implications of these new results within the frame of the current theories of plasma bubble onset.

  19. Geomagnetic response to IMF and solar wind over different latitudes

    NASA Astrophysics Data System (ADS)

    Aslam, A. M.; Tripathi, Sharad Chandra; Mansoori, Azad Ahmad; Waheed, Malik Abdul

    2016-07-01

    In this paper a study on the response of geomagnetic field characteristics to the solar wind variation during three solar cycles (SC 21, SC 22, SC 23) have been conducted in a long term scale. The difference in the response of two different latitudinal characteristic indices has been investigated. For the purpose we have considered the high latitude index AE and the mid-latitude aa index and both gives the knowledge about the perturbations in the geomagnetic field conditions. Eventually we can infer the idea about the ionospheric current system changes in response to the solar wind conditions. The variation found in the AE and aa indices have been found to follow a 11 year cycle as similar to the sunspot variation. Also the correlation between the annual means of the solar wind parameters velocity V, magnetic filed B and the composite parameters BV and BV ^{2 } have been calculated . A difference was found between the correlations obtained for the AE and aa indices. We could also see that the difference in correlation follows a cyclic pattern i.e. the large difference is found during the solar maxima while a small difference is observed during the minima.

  20. Ionosonde observations of daytime spread F at low latitudes

    NASA Astrophysics Data System (ADS)

    Jiang, Chunhua; Yang, Guobin; Liu, Jing; Yokoyama, Tatsuhiro; Komolmis, Tharadol; Song, Huan; Lan, Ting; Zhou, Chen; Zhang, Yuannong; Zhao, Zhengyu

    2016-12-01

    Spread F on ionograms has been considered to be a phenomenon mainly occurred at nighttime. This study presented a case study of daytime spread F observed by the ionosonde installed at Puer (PUR; 22.7°N, 101.05°E; dip latitude 12.9°N), where daytime spread F that lasted for more than 2 h (about 08:30 LT 10:45 LT) was observed on 14 November 2015. To investigate the possible mechanism, ionograms recorded at PUR and Chiang Mai (18.76°N, 98.93°E; dip latitude 9.04°N) were used in this study. We found that traveling ionospheric disturbances were observed before the occurrence of daytime spread F. Meanwhile, the movement of the peak height of the ionosphere was downward. We suggested that downward vertical neutral winds excited by traveling atmospheric disturbances/atmospheric gravity waves might play a significant role in forming daytime spread F over PUR during geomagnetic storms.

  1. Magnetic field draping at the low-latitude magnetopause

    NASA Technical Reports Server (NTRS)

    Richard, R. L.; Lotko, W.

    1991-01-01

    Magnetohydrodynamic simulations are used to investigate the structure of the low-latitude magnetopause for interplanetary magnetic field conditions with a dominant southward component. The structure is self-consistently calculated as an initial-value problem in which the system is allowed to evolve into a quasi-steady state. All components of the 3D velocity and magnetic field as well as compressibility, resistivity, and viscosity are included in the 2D calculation. The simulation model shows that magnetic field draping can occur at the magnetopause boundary when magnetic merging takes place in the presence of a tangential shear flow. For 'normal' (positive Bx) draping, the higher-latitude portion of the field lines are curved toward the sun on the magnetospheric side of the magnetopause and away from the sun on the magnetosheath side. The thickness of the normal draping structure scales with the viscosity. The field-aligned current system that accompanies normal magnetic draping is consistent with the sense of the region 1 currents that flow into the dayside ionosphere.

  2. Map of Martian Potassium at Mid-Latitudes

    NASA Image and Video Library

    2003-03-13

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element potassium. Potassium, having the chemical symbol K, is a naturally radioactive element and is a minor constituent of rocks on the surface of both Mars and Earth. The region of highest potassium content, shown in red, is concentrated in the northern part of Acidalia Planitia (centered near 55 degrees N, -30 degrees). Several areas of low potassium content, shown in blue, are distributed across the mid-latitudes, with two significant low concentrations, one associated with the Hellas Basin (centered near 35 degrees S, 70 degrees) and the other lying southeast of Elysium Mons (centered near 10 degrees N, 160 degrees). Contours of constant surface elevation are also shown. The long continuous line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south. http://photojournal.jpl.nasa.gov/catalog/PIA04255

  3. Seedling mortality from litterfall increases with decreasing latitude.

    PubMed

    Gillman, Len N

    2016-02-01

    Global patterns in ecology need to be identified and interpreted if macroecological processes are to be fully understood. Facilitating effects on seedlings such as that of nurse plants and competitive effects such as allelopathy have been well recognized but the importance of plants acting as killers through physical damage by the litterfall they produce has received relatively little attention. Here I examine latitudinal patterns of physical disturbance to seedlings (microdisturbance) due to litterfall and discuss the macroecological implications in light of current research. Analyses of results from published studies show that both the risk of litterfall disturbance, as measured using artificial model seedlings, and the proportion of seedling mortalities due to litterfall decrease significantly with increasing latitude. Patterns of microdisturbance appear to be driven by the dynamic interaction between macro-litterfall, safe sites with protective overhead vegetation, topography, and animal activity. However, we are informed on this subject by few studies. There is evidence, again from a limited number of studies, for considerable spatial heterogeneity in microdisturbance intensity and for seedling resilience to litterfall damage to differ substantially among species. Therefore, differential survival among microsites may produce regeneration niche diversity. However, more focused studies are required across a range of forest types and latitudes before these results can be generalized. Therefore, there is fertile ground for researchers to use comparable multifactorial methods to investigate the implications of microdisturbance at macro-ecological scales.

  4. Tropical and mid-latitude forcing of continental Antarctic temperatures

    NASA Astrophysics Data System (ADS)

    Turney, C. S. M.; Fogwill, C. J.; Klekociuk, A.; van Ommen, T. D.; Curran, M. A. J.; Moy, A. D.; Palmer, J. G.

    2015-07-01

    Future changes in atmospheric circulation and associated modes of variability are a major source of uncertainty in climate projections. Nowhere is this issue more acute than across the mid- to high-latitudes of the Southern Hemisphere (SH) which over the last few decades has experienced extreme and regional variable trends in precipitation, ocean circulation, and temperature, with major implications for Antarctic ice melt and surface mass balance. Unfortunately there is a relative dearth of observational data, limiting our understanding of the driving mechanism(s). Here we report a new 130-year annually-resolved record of δ D - a proxy for temperature - from the South Geographic Pole where we find a significant influence from extra-tropical pressure anomalies which act as "gatekeepers" to the meridional exchange of air masses. Reanalysis of global atmospheric circulation suggests these pressure anomalies play a considerably larger influence on mid- to high-latitude SH climate than hitherto believed, modulated by the tropical Pacific Ocean. Our findings suggest that future increasing tropical warmth will strengthen meridional circulation, exaggerating current trends, with potentially significant impacts on Antarctic surface mass balance.

  5. Anomalous variations of tropopause height in low latitude regions

    NASA Astrophysics Data System (ADS)

    Ramkumar, T. K.; Narayana Rao, D.

    Successful attempts have been made in early 1990s to link the possible influence of equatorial stratospheric quasi-biennial-oscillation QBO on tropopause dynamics at longer period scales leading ultimately to the evolution of strong El Nino events of global economic importance Gray et al 1992 GRL JMSJ As a result of this influence it is possible that the tropopause height may be increasing instead of decreasing with latitude from the equator in tropical regions during particular phase of QBO say westerly phase over the equator In the present work we report such observations using radiosonde data obtained from fourteen different tropical 30 N to 30 S radio-sounding stations located in the wide longitudinal zone of South East Asia South Pacific and Africa in the year 2004 The daily tropopause height determined at 00 00 and 12 00 hrs GMT is averaged for each month separately The tropopause height Cold Point Tropopause CPT is determined by noting the height of minimum temperature between 12 and 20 km It is observed further that the latitude variation of tropopause height in southern Hemisphere is much less when compared to that in the Northern Hemisphere The reason for this asymmetric characteristic of tropopause about the equator may be that greater fraction of the northern hemisphere is covered with land and it is ocean in the southern hemisphere Because of large variations in topography of the land and the associated thermal conductivity it is possible that convection activities of the

  6. Evapotranspiration Cycles in a High Latitude Agroecosystem: Potential Warming Role.

    PubMed

    Ruairuen, Watcharee; Fochesatto, Gilberto J; Sparrow, Elena B; Schnabel, William; Zhang, Mingchu; Kim, Yongwon

    2015-01-01

    As the acreages of agricultural lands increase, changes in surface energetics and evapotranspiration (ET) rates may arise consequently affecting regional climate regimes. The objective of this study was to evaluate summertime ET dynamics and surface energy processes in a subarctic agricultural farm in Interior Alaska. The study includes micrometeorological and hydrological data. Results covering the period from June to September 2012 and 2013 indicated consistent energy fractions: LE/Rnet (67%), G/Rnet (6%), H/Rnet (27%) where LE is latent heat flux, Rnet is the surface net radiation, G is ground heat flux and H is the sensible heat flux. Additionally actual surface evapotranspiration from potential evaporation was found to be in the range of 59 to 66%. After comparing these rates with those of most prominent high latitude ecosystems it is argued here that if agroecosystem in high latitudes become an emerging feature in the land-use, the regional surface energy balance will significantly shift in comparison to existing Arctic natural ecosystems.

  7. Postmidnight ionospheric troughs in summer at high latitudes

    NASA Astrophysics Data System (ADS)

    Voiculescu, M.; Nygrén, T.; Aikio, A. T.; Vanhamäki, H.; Pierrard, V.

    2016-12-01

    In this article we identify possible mechanisms for the formation of postmidnight ionospheric troughs during summer, in sunlit plasma. Four events were identified in measurements of European Incoherent Scatter and ESR radars during CP3 experiments, when the ionosphere was scanned in a meridional plan. The spatial and temporal variation of plasma density, ion, and electron temperatures were analyzed for each of the four events. Super Dual Auroral Radar Network plasma velocity measurements were added, when these were available. For all high-latitude troughs the ion temperatures are high at density minima (within the trough), at places where the convection plasma velocity is eastward and high. There is no significant change in electron temperature inside the trough, regardless of its temporal evolution. We find that troughs in sunlit plasma form in two steps: the trough starts to form when energetic electron precipitation leads to faster recombination in the F region, and it deepens when entering a region with high eastward flow, producing frictional heating and further depleting the plasma. The high-latitude plasma convection plays an important role in formation and evolution of troughs in the postmidnight sector in sunlit plasma. During one event a second trough is identified at midlatitudes, with different characteristics, which is most likely produced by a rapid subauroral ion drift in the premidnight sector.

  8. SIMULATED FARADAY ROTATION MEASURES TOWARD HIGH GALACTIC LATITUDES

    SciTech Connect

    Akahori, Takuya; Kim, Jongsoo; Ryu, Dongsu; Gaensler, B. M. E-mail: akahori@physics.usyd.edu.au E-mail: ryu@canopus.cnu.ac.kr

    2013-04-20

    We study the Faraday rotation measure (RM) due to the Galactic magnetic field (GMF) toward high Galactic latitudes. The RM arises from the global, regular component as well as from the turbulent, random component of the GMF. We model the former based on observations and the latter using the data of magnetohydrodynamic turbulence simulations. For a large number of different GMF models, we produce mock RM maps around the Galactic poles and calculate various statistical quantities with the RM maps. We find that the observed medians of RMs toward the north and south Galactic poles, {approx}0.0 {+-} 0.5 rad m{sup -2} and {approx} + 6.3 {+-} 0.5 rad m{sup -2}, are difficult to explain with any of our many alternate GMF models. The standard deviation of observed RMs, {approx}9 rad m{sup -2}, is clearly larger than that of simulated RMs. The second-order structure function of observed RMs is substantially larger than that of simulated RMs, especially at small angular scales. We discuss other possible contributions to RM toward high Galactic latitudes. Besides observational errors and the intrinsic RM of background radio sources against which RM is observed, we suggest that the RM due to the intergalactic magnetic field may account for a substantial fraction of the observed RM. Finally, we note that reproducing the observed medians may require additional components or/and structures of the GMF that are not present in our models.

  9. Silicon-carbon interactions in high latitude watersheds

    NASA Astrophysics Data System (ADS)

    Humborg, C.; Morth, C.; Struyf, E.; Conley, D. J.

    2008-12-01

    Changes in climate and hydrology in high latitude regions could liberate large amounts of previously inactive organic carbon (OC) during a prolonging thawing period, and new studies have shown that a great deal of this organic C is remineralized as CO2 during its transport to the sea. However, OC (with its origin in atmospheric carbon) and dissolved silicate (DSi) concentrations in taiga and tundra rivers are intimately linked, and higher concentrations of weathering products are found in taiga and tundra rivers with a higher percentage of peat in their watersheds. It appears that the weathering regime of taiga and tundra watersheds is tightly linked to carbon-silicon interactions, in which carbon acts both as a weathering agent (soil CO2 from degradation of OC) and as a weathering product (DSi and bicarbonate). Whereas respiration of OC can be regarded as a positive feedback to global warming, weathering can be regarded as a negative feedback to global warming since atmospheric CO2 is converted to bicarbonate and thereby locked into the aquatic phase for geological time scales. Thus, bicarbonate export may compensate for significant amounts of exported OC thereby reducing the positive feedback to atmospheric CO2. However, the silicon-carbon interactions are not straight forward as suggested by classical inverse modelling,using the stochiometry of rock forming minerals as base, since high latitude wetlands contain a massive stock of amorphous silica (diatoms and phytoliths) buffering the actual DSi export, suggesting that the Si cycle is to a large extent biologically controlled.

  10. The ionospheric storms in the American sector and their longitudinal dependence at the northern middle latitudes

    NASA Astrophysics Data System (ADS)

    Liu, Wenjing; Xu, Liang; Xiong, Chao; Xu, Jisheng

    2017-01-01

    On the basis of the total electron content (TEC) observations from Madrigal database, we have made a statistical analysis of the ionospheric response during 217 geomagnetic storms from the year 2001 to 2015, including observations at 6 different latitude zones along one meridian in the American sector and 4 different longitudes at the middle latitude zone. Our results show that the ionospheric storm has prominent latitudinal dependence, with negative storm prevailing at high latitudes and positive storm at lower latitudes. The maximum ratio of positive to negative storms is observed at around 30°N magnetic latitude. The ionospheric response depends also on the phases of the storm. The occurrence of positive storm decreases during recovery phase when compared to that during main phase, while the negative storm presents opposite pattern. However, the occurrence of positive storm increases at equatorial and low latitudes during recovery phase. Additionally, during main phase, the occurrence of negative storm is higher at equatorial and low latitudes than that at middle latitudes. The local time dependences of the ionospheric storm onsets are quite different for different latitudes. The negative storm mainly occurs from post-middle night to morning hours and the positive storm mainly occurs during daytime at middle latitudes; while both the positive and negative storms mainly occur during nighttime at equatorial latitude. For all latitudes, the typical time delay between the main phase onset and the onset time of ionospheric negative storm is longer than 10 h, while it is shorter than 10 h for positive storm (expect at low and equatorial latitudes). We further check the longitudinal dependence of the ionospheric storm at middle latitude, and find that the occurrence of positive storm is higher in American and Asian sectors than that in European sector, and the non-significant storm is mostly observed in European sector. The 'forbidden time interval' of negative storm

  11. Interconnect Performance Evaluation of SGI Altix 3700 BX2, Cray X1, Cray Opteron Cluster, and Dell PowerEdge

    NASA Technical Reports Server (NTRS)

    Fatoohi, Rod; Saini, Subbash; Ciotti, Robert

    2006-01-01

    We study the performance of inter-process communication on four high-speed multiprocessor systems using a set of communication benchmarks. The goal is to identify certain limiting factors and bottlenecks with the interconnect of these systems as well as to compare these interconnects. We measured network bandwidth using different number of communicating processors and communication patterns, such as point-to-point communication, collective communication, and dense communication patterns. The four platforms are: a 512-processor SGI Altix 3700 BX2 shared-memory machine with 3.2 GB/s links; a 64-processor (single-streaming) Cray XI shared-memory machine with 32 1.6 GB/s links; a 128-processor Cray Opteron cluster using a Myrinet network; and a 1280-node Dell PowerEdge cluster with an InfiniBand network. Our, results show the impact of the network bandwidth and topology on the overall performance of each interconnect.

  12. An evaluation of the Well at Dell health management program: health risk change and financial return on investment.

    PubMed

    Musich, Shirley; McCalister, Tre'; Wang, Sara; Hawkins, Kevin

    2015-01-01

    To investigate the effectiveness of the Well at Dell comprehensive health management program in delivering health care and productivity cost savings relative to program investment (i.e., return on investment). A quasi-experimental design was used to quantify the financial impact of the program and nonexperimental pre-post design to evaluate change in health risks. Ongoing worksite health management program implemented across multiple U.S. locations. Subjects were 24,651 employees with continuous medical enrollment in 2010-2011 who were eligible for 2011 health management programming. Incentive-driven, outcomes-based multicomponent corporate health management program including health risk appraisal (HRA)/wellness, lifestyle management, and disease management coaching programs. Medical, pharmacy, and short-term disability pre/post expenditure trends adjusted for demographics, health status, and baseline costs. Self-reported health risks from repeat HRA completers. Analysis: Propensity score-weighted and multivariate regression-adjusted comparison of baseline to post trends in health care expenditures and productivity costs for program participants and nonparticipants (i.e., difference in difference) relative to programmatic investment. The Well at Dell program achieved an overall return on investment of 2.48 in 2011. Most of the savings were realized from the HRA/wellness component of the program. Cost savings were supported with high participation and significant health risk improvement. An incentive-driven, well-managed comprehensive corporate health management program can continue to achieve significant health improvement while promoting health care and productivity cost savings in an employee population.

  13. Recent low-latitude freeze thaw on Mars

    NASA Astrophysics Data System (ADS)

    Page, David P.

    2007-07-01

    Outside polar latitudes, features corresponding to surface thaw have yet to be identified on Mars. The youthful gully landforms observed at mid-high latitude [Malin, M., Edgett, K., 2000. Science 288, 2330-2335] are the nearest candidate, but the source (and nature) of the gully carving agent remains controversial [e.g., Musselwhite, D.S., Swindle, T.D., Lunine, J.I., 2001. Geophys. Res. Lett. 28, 1283-1285; Mellon, M.T., Phillips, R.J., 2001. J. Geophys. Res. 106, 1-15; Knauth, L.P., Burt, D.M., 2002. Icarus 158, 267-271; Costard, F., Forget, F., Mangold, N., Peulvast, J.P., 2002. Science 295, 110-113; Christensen, P.R., 2003. Nature 422, 45-48; Treiman, A.H., 2003. J. Geophys. Res. 108]. At higher obliquity than the present epoch, near-surface ground ice should be present globally [Mellon, M.T., Jakosky, B.M., 1995. J. Geophys. Res. 100 (E6), 11781-11799], populated by condensation of atmospheric water vapour in the top few metres of the regolith, or emplaced as dusty ice sheets reaching down towards the equator. The latitudinal restriction of these gullies to regions poleward of ±30° appears to argue against a thaw component to their formation—since ground ice is present and stable at all latitudes at high obliquity, the current (low) obliquity regime should result in ground ice thaw at low latitudes, where insolation and daytime temperatures are currently greatest, and this is not observed. A previously undescribed meltwater sequence in the Cerberus plains, at 20° N/187° E, shows that comparable, but much more continuous, and mappable melting and surface runoff have occurred in the geologically recent past at near-equatorial latitudes on Mars. Polygonal ground in the Cerberus plains is seen by the Mars Global Surveyor Mars Orbiter Camera (MOC) to suffer sequential, regional-scale volatile-loss consistent with thaw of near-surface ground ice under periglacial conditions. This degradation is continuously sampled by a single MOC strip, showing an icy

  14. Climatology of GNSS ionospheric scintillation at high latitudes

    NASA Astrophysics Data System (ADS)

    Spogli, L.; Alfonsi, L.; de Franceschi, G.; Romano, V.; Aquino, M.; Dodson, A.; Mitchell, C. N.

    2009-12-01

    Under perturbed conditions caused by intense solar wind magnetosphere coupling, the ionosphere may become highly turbulent and irregularities, typically enhancements or depletions of the electron density embedded in the ambient ionosphere, can form. Such irregularities cause diffraction effects, mainly due to the random fluctuations of the refractive index of the ionosphere, on the satellites signals passing through them and consequent perturbations may cause GNSS navigation errors and outages, abruptly corrupting its performance. Due to the morphology of the geomagnetic field, whose lines are almost vertical at high latitude, polar areas are characterized by the presence of significant ionospheric irregularities having scale sizes ranging from hundreds of kilometers down to a few centimeters and with highly dynamic structures. The understanding of the effect of such phenomena is important, not only in preparation for the next solar cycle (24), whose maximum is expected in 2012, but also for a deeper comprehension of the dynamics of the high-latitude ionosphere. We analyze the fluctuations in the carrier frequency of the radio waves received on the ground, commonly referred to as ionospheric amplitude and phase scintillations, to investigate the physical processes causing them. The phase scintillations on GNSS signals are likely caused by ionospheric irregularities of scale size of hundreds of meters to few kilometers. The amplitude scintillations on GNSS signals are caused by ionospheric irregularities of scale size smaller than the Fresnel radius, which is of the order of hundreds of meters for GNSS signals, typically embedded into the patches. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Institute of Engineering Surveying and Space Geodesy (IESSG) of the University of Nottingham manage the same kind of GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers over the European high and mid latitude regions and over Antarctica. The

  15. A Mid-Latitude Geomorphologic Map of Titan

    NASA Astrophysics Data System (ADS)

    Lopes, Rosaly M. C.; Malaska, Michael; Schoenfeld, Ashley; Solomonidou, Anezina; Birch, Samuel; Hayes, Alexander; Williams, David A.; Janssen, Michael A.; Le Gall, Alice; Turtle, Elizabeth P.; Radebaugh, Jani; Cassini RADAR Team

    2016-10-01

    We investigated the geologic history of Titan through mapping and analyzing the distribution of observed geomorphic features using a combination of Cassini data collected by RADAR, VIMS, and ISS. Determining the spatial and superposition relationships between geomorphologic units on Titan leads to an understanding of the likely time evolution of the landscape and gives insight into the process interactions that drive its evolution. We have used all available datasets to extend the mapping initially done by Lopes et al. [1]. We now have the mid-latitudes (60N to 60S) of Titan mapped at 1:800,000 scale in all areas covered by Synthetic Aperture Radar (SAR). A map of the polar regions has been done by Birch et al. [2]. For the mid-latitudes, we have defined five broad classes of terrains following Malaska et al. [3], largely based on prior mapping [1]. These broad classes are: craters, hummocky/mountainous, labyrinth, plains, and dunes. We have found that the hummocky/mountainous terrains are the oldest units on the surface and appear radiometrically cold, indicating icy materials [5]. Dunes are the youngest units and appear radiometrically warm, indicating organic sediments. VIMS analysis shows that compositional variations can also exist within the same class of unit [6, 7]. Future work aims to combine the polar maps of Birch et al. [2] with the mid-latitude maps presented here and harmonize the units at the 60 degrees boundaries. We also plan to extend the map in regions not covered by SAR to produce a 1:1,500,000 scale map compatible with USGS standards.References: [1] Lopes, R.M.C., et al.: Icarus, 205, 540-588, 2010; [2] Birch et al., submitted to Icarus. [3] Malaska, M., et al.: Icarus, 270, 130-161, 2016; [4] Barnes, J., et al.: Pl. Scie., 2:1, 2013; [5] Janssen et al., 2016 Icarus 270, 443-459, 2016. [6] Solomonidou, A., et al. : DPS abstract, 2016. [7] Lopes, R.M.C., et al, Icarus, 270, 162-182, 2016.

  16. Ionospheric vertical drift response at a mid-latitude station

    NASA Astrophysics Data System (ADS)

    Kouba, Daniel; Koucká Knížová, Petra

    2016-07-01

    Vertical plasma drift data measured at a mid-latitude ionospheric station Pruhonice (50.0 ° N, 14.6 ° E) were collected and analysed for the year 2006, a year of low solar and geomagnetic activity. Hence these data provide insight into the drift behaviour during quiet conditions. The following typical diurnal trend is evident: a significant decay to negative values (downward peak) at dawn; generally less pronounced downward peak at dusk hours. Magnitude of the downward drift varies during the year. Typically it reaches values about 20 ms-1 at dawn hours and 10 ms-1 at dusk hours. Maximum dawn magnitude of about 40 ms-1 has been detected in August. During daytime the vertical drifts increases from the initial small downward drifts to zero drift around noon and to small upward drifts in the afternoon. Night-time drift values display large variability around a near zero vertical drift average. There is a significant trend to larger downward drift values near dawn and a less pronounced decrease of the afternoon upward vertical drifts near sunset. Two regular downward peaks of the drift associated with the dawn and dusk are general characteristics of the analysed data throughout the year 2006. Their seasonal course corresponds to the seasonal course of the sunrise and sunset. The duration of prevailing negative drift velocities forming these peaks and thus the influence of the dawn/dusk on the drift velocity is mostly 1.5-3 h. The dawn effect on vertical drift tends to be larger than the effect of the dusk. The observed magnitude of the sunrise and sunset peaks show significant annual course. The highest variability of the magnitude is seen during winter. High variability is detected till March equinox and again after September equinox. Around solstice, both peaks reaches lowest values. After that, the magnitudes of the drift velocity increase smoothly till maxima in summer (August). The vertical drift velocity course is smooth between June solstice and September

  17. Seasonal affective disorder in college students: prevalence and latitude.

    PubMed

    Low, K G; Feissner, J M

    1998-11-01

    The Seasonal Pattern Assessment Questionnaire and the Beck Depression Inventory were used to evaluate a convenience sample of college students in northern New England for winter seasonal affective disorder (SAD) and subsyndromal SAD. Seventy-six students filled out the questionnaire and the inventory in mid-fall, then completed the inventory again in mid-February. The students who had moved from southern latitudes to northern New England were the most likely to experience increased depression in winter. Prevalence rates for SAD and sub-SAD combined (winter 13.2 and 19.7%, respectively) were slightly higher than those reported in previous research. The prevalence of SAD was also higher in female students, which was consistent with findings in previous research.

  18. Wintertime density perturbations near 50 km in relation to latitude

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.

    1977-01-01

    Standard and reference atmospheres which depict the horizontal distribution of air density in the stratosphere and mesosphere are not realistic in that they do not provide information on the large departures from standard that may occur during a given month, nor on the time- and space-scales of atmospheric perturbations responsible for these departures. In the present paper, it is shown how this information can be obtained from a special analysis of satellite radiance measurements. Plots of the mean zonal radiance, obtained with the VTPR instrument, and the corresponding 50-km density show not only the expected strong poleward gradient of density, but also a strong density surge from late December to early January, affecting all latitudes.

  19. Effect of latitude on flavonoid biosynthesis in plants.

    PubMed

    Jaakola, Laura; Hohtola, Anja

    2010-08-01

    The growth conditions in different latitudes vary markedly with season, day length, light quality and temperature. Many plant species have adapted well to the distinct environments through different strategies, one of which is the production of additional secondary metabolites. Flavonoids are a widely spread group of plant secondary metabolites that are involved in many crucial functions of plants. Our understanding of the biosynthesis, occurrence and function of flavonoids has increased rapidly in recent decades. Numerous studies have been published on the influence of environmental factors on the biosynthesis of flavonoids. However, extensive long-term studies that examine the effect of the characteristics of northern climates on flavonoid biosynthesis are still scarce. This review focuses on the current knowledge about the effect of light intensity, photoperiod and temperature on the gene-environment interaction related to flavonoid biosynthesis in plants.

  20. Ion properties of the high-latitude middle-atmosphere

    NASA Technical Reports Server (NTRS)

    Li, C.; Mitchell, J. D.; Brink, R. D.; Croskey, C. L.; Hale, L. C.

    1994-01-01

    Investigations of high-latitude, middle-atmosphere ion properties have been conducted using rocket probe techniques. Electrodynamics studies have addressed: mesospheric dynamics and small-scale structure (the MAC/EPSILON Campaign during October-November 1977); ionization effects associated with highly energetic greater than or equal to 1 MeV) precipitating electrons (the MAC/REP Program during May 1990); and the characteristics of noctilucent cloud (NLC) and polar mesosphere summer echo (PMSE) regions (the NLC-91 Campaign during July-August 1991). Recent developments in Gerdien condenser probe theory, using computational fluid dynamics to model ion collection, have resulted in more accurate evaluation of the ion mobilities and number densities. Measurements of very small ion mobilities are thought to indicate an aerosol ion presence in the upper mesosphere.

  1. Mid-latitude VLF emissions observed in the topside ionosphere

    NASA Technical Reports Server (NTRS)

    Ondoh, T.; Murakami, T.

    1975-01-01

    Narrow-band VLF emissions observed on different days by Alouette-2 are described. It is found that narrow-band VLF hiss (3.5-7.0 kHz) occurs at midlatitudes (at 54 to 64 deg) in the topside ionosphere during both the geomagnetically disturbed and quiet periods, although the hiss region moves towards the auroral zone during the disturbed period. It is likely that the midlatitude hiss at around 5 kHz is the origin of the narrow-band hiss (5 plus or minus 1 kHz) often observed at ground stations at low latitudes, since no VLF emissions above 2 kHz appear in the auroral zone. The midlatitude VLF hiss observed in the topside ionosphere may be generated by the transverse (electron cyclotron) resonance instability in the magnetosphere.

  2. Altitude and latitude dependence of the equatorial electrojet

    NASA Astrophysics Data System (ADS)

    Singh, A.; Cole, K. D.

    1988-07-01

    A self-consistent and high-resolution dynamo model is used to investigate the effects of day-to-day or seasonal variation of altitude and latitude profiles of the E-plasma density in the equatorial ionosphere on equatorial electrojet (EEJ) structure. Variations in the E-layer peak altitude and amplitude are shown to significantly affect EEJ structure. The results indicate that, for any shape, the EEJ peak appears at or below the E-layer peak altitude. Distinct double peaks occur in the EEJ structure if the E-layer peak is above 105 km or if the gradient is large. The effect of the latitudinal variation of the integrated conductivities of ionospheric field lines upon the amplitude and altitude of the EEJ peak is discussed.

  3. The Ulysses mission in the high latitude heliosphere

    NASA Technical Reports Server (NTRS)

    Page, D. E.; Marsden, R. G.; Smith, E. J.; Wenzel, K.-P.

    1990-01-01

    Ulysses, a joint ESA/NASA mission launched in October 1990, will be the first to explore the high latitude heliosphere. Launch will be from the Shuttle and a Jupiter gravity assist will be used to send the spacecraft first over the southern solar pole approximately three and one half years after launch and then over the northern solar pole one year later. Instruments will be carried to study the solar wind, the heliospheric magnetic field, energetic solar particles, galactic cosmic rays, solar X-rays, cosmic gamma rays, cosmic dust and interstellar neutral helium. The radio signals used to track and transmit spacecraft data will be used also to sound the corona and to search for gravitational waves.

  4. High-latitude day side electric field and particle measurements

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.; Johnstone, A. D.

    1974-01-01

    Two rockets carrying electric field and low-energy particle instrumentation were launched near noon at 80 deg magnetic latitude. One flight encountered polar cap conditions only, whereas the other traversed part of the polar cusp. Although weak particle precipitation was measured on both flights, bursts of intense magnetosheath-type electron fluxes were detected on the latter. Strong electric fields such as would result from antisunward convection were observed during both flights. The measurements are compared with results obtained by other types of spacecraft and are interpreted in the light of those data. It is concluded that direct access of magnetosheath electrons is very variable and occurs in small regions within a larger overall region.-

  5. Multiple Satellite Observations of High-Latitude Ionospheric Outflows

    NASA Technical Reports Server (NTRS)

    Horwitz, J.; Zeng, W.; Stevenson, B. A.; Wu, X.-Y.; Germany, G. A.; Craven, Paul D.; Rich, F. J.; Moore, T. E.

    2000-01-01

    We will present reported observations of up- and down-flows of topside ionospheric thermal plasmas from multiple near-simultaneous tracks through the high-latitude topside ionosphere. From several Southern polar passes, it has been possible to construct plots of field-aligned flows of O+ observed by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft near 5000 km altitude together with vertical ion flow observations from one or more DMSP spacecraft near 800 km altitude. We will also involve simulations from our Dynamic Fluid-Kinetic(DyFK) modeling of polar plasma transport and display resulting altitude profiles of ion parallel velocities and densities, and overlay those profiles with the "conjunction" measurements by DMSP(800 km) and POLAR(approx. 5000 km altitude). We also will present simultaneous observations of POLAR auroral UVI images with field-aligned flows.

  6. High-latitude geomagnetic studies (22-23 millihertz)

    SciTech Connect

    Wolfe, A. City Univ. of New York, Brooklyn ); Lanzerotti, L.J.; Maclennan, C.C.; Medford, L.V. )

    1988-01-01

    Geomagnetic field measurements were initiated at Iqaluit (formerly Frobisher Bay) in the Northwest Territories of Canada during July 1985 (Wolfe et al. 1986). This site was selected because it was calculated to be in the conjugate area to the Amundsen-Scott South Pole Station where extensive geomagnetic research has been conducted. The principal scientific objectives are to study the conjugacy of high-latitude magnetic fluctuations observed at Iqaluit and South Pole (L{approximately}13). In this report, the authors extend the previous report of Wolfe et al. (1987) and comment upon the conjugacy of the stations for magnetic field fluctuations in the Pc3 (22-33 millihertz) hydromagnetic regime and upon the penetration of hydromagnetic energy deeper into the magnetosphere on the local dayside.

  7. Preliminary prediction model for the ROTI index at high latitude

    NASA Astrophysics Data System (ADS)

    Rochel Grimald, Sandrine; Boscher, Daniel; Fabbro, Vincent; Rougerie, Sébastien

    2017-04-01

    The variation of electron density can be described by the ROTI index (i.e. the Rate of change of Total electron content Index). This index is indicative of the electron density gradients which can be responsible of loss of satellite communications or loss of lock of GNSS system.. At high latitude, the ionosphere is connected to the magnetosphere through the magnetic field lines. When the magnetic activity increases, particles from the magnetosphere are injected in the ionosphere along the magnetic field lines. They disturb the ionospheric layer and are responsible of changes in the ROTI index. In this paper, we will use the NOAA POES satellites data to study the link between the ROTI index value and the particles flux in the inner magnetosphere. Then we will use the results to developp a preliminary ROTI model.

  8. A mathematical model of the middle and high latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.

    1988-01-01

    A time-dependent three-dimensional model of the middle and high latitude ionosphere is described. The density distributions of six ion species NO(+), O(2+), N(2+), O(+), N(+), He(+), and the electron and ion temperatures are obtained from a numerical solution of the appropriate continuity, momentum, and energy equations. The equations are solved as a function of height for an inclined magnetic field at E and F region altitudes. The three-dimensional nature of the model is obtained by following flux tubes of plasma as they convect or corotate through a moving neutral atmosphere. The model takes account of field-aligned diffusion, cross-field electrodynamic drifts, thermospheric winds, polar wind escape, energy-dependent chemical reactions, neutral composition changes, ion production due to solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow and local heating and cooling processes. The model also takes account of the offset between the geomagnetic and geographic poles.

  9. Ion properties of the high-latitude middle-atmosphere

    NASA Technical Reports Server (NTRS)

    Li, C.; Mitchell, J. D.; Brink, R. D.; Croskey, C. L.; Hale, L. C.

    1994-01-01

    Investigations of high-latitude, middle-atmosphere ion properties have been conducted using rocket probe techniques. Electrodynamics studies have addressed: mesospheric dynamics and small-scale structure (the MAC/EPSILON Campaign during October-November 1977); ionization effects associated with highly energetic greater than or equal to 1 MeV) precipitating electrons (the MAC/REP Program during May 1990); and the characteristics of noctilucent cloud (NLC) and polar mesosphere summer echo (PMSE) regions (the NLC-91 Campaign during July-August 1991). Recent developments in Gerdien condenser probe theory, using computational fluid dynamics to model ion collection, have resulted in more accurate evaluation of the ion mobilities and number densities. Measurements of very small ion mobilities are thought to indicate an aerosol ion presence in the upper mesosphere.

  10. Characterizing the Spatio-Temporal Response of High Latitude Convection

    NASA Astrophysics Data System (ADS)

    Stoneback, R.

    2015-12-01

    High latitude convection is a highly variable system in time influenced by multiple processes, presenting a significant challenge when trying to isolate the response to only one of these inputs. We will present a data based method that can isolate systematic variations within the incomplete convection information provided by SuperDARN and DMSP as well as measurements of space weather parameters in time over an 11 year solar cycle. These variations are condensed into a limited set of basis functions with corresponding amplitudes in time that best reproduce the long term data set, in effect producing an estimate of convection at all locations ever measured by SuperDARN or DMSP and at all times over the solar cycle.

  11. High latitude equivalent current systems during extremely quiet times

    NASA Technical Reports Server (NTRS)

    Rostoker, G.; Chen, A. J.; Yasuhara, F.; Akasofu, S.-I.; Kawasaki, K.

    1974-01-01

    The magnetic perturbation patterns in the polar cap and auroral zone regions are obtained for extremely quiet days using two different techniques. It is shown that the form of the equivalent current flow pattern is extremely sensitive to the level of quietness, and that even so-called quiet days are at times disturbed by substorm activity. Certain characteristic equivalent flow not typically observed during substorms is noted in the polar cap, and this flow appears to be associated with effects of polar cap perturbations discussed by Svalgaard (1973). A region of equatorward flow at high latitudes near the dawn meridian, appears to be Hall current driven by an eastward electric field. The dayside sub-auroral zone is dominated by the Sq-current system, while the nightside shows no significant current flow in the absence of substorm activity.

  12. Anisotropy of high-latitude nighttime F region irregularities

    SciTech Connect

    Livingston, R.C.; Rino, C.L.; Owen, J.; Tsunoda, R.T.

    1982-12-01

    The anisotropy of intermediate-scale, F region irregularities in the nighttime auroral zone is described. The study is based upon spaced-receiver phase scintillation measurements made with the Wideband satellite at Poker Flat, Alaska. A systematic dependence of irregularity anisotropy with local time and magnetic latitude is observed, suggesting convective control. Sheetlike irregularities are confined to the zone of east-west drift near the equatorward boundary of the auroral zone, and at the flow reversal, or Harang discontinuity, the cross-field extension of the sheets is reduced. The extension of rodlike irregularities, which are observed poleward of the zonal convection boundary, also shows apparent convection dominance. Mechanisms for convection control of the anisotropy are discussed.

  13. Wintertime density perturbations near 50 km in relation to latitude

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.

    1977-01-01

    Standard and reference atmospheres which depict the horizontal distribution of air density in the stratosphere and mesosphere are not realistic in that they do not provide information on the large departures from standard that may occur during a given month, nor on the time- and space-scales of atmospheric perturbations responsible for these departures. In the present paper, it is shown how this information can be obtained from a special analysis of satellite radiance measurements. Plots of the mean zonal radiance, obtained with the VTPR instrument, and the corresponding 50-km density show not only the expected strong poleward gradient of density, but also a strong density surge from late December to early January, affecting all latitudes.

  14. Do wintering Harlequin Ducks forage nocturnally at high latitudes?

    USGS Publications Warehouse

    Rizzolo, D.J.; Esler, Daniel; Roby, D.D.; Jarvis, R.L.

    2005-01-01

    We monitored radio-tagged Harlequin Ducks (Histrionicus histrionicus) to determine whether nocturnal feeding was part of their foraging strategy during winter in south-central Alaska. Despite attributes of our study site (low ambient temperatures, harsh weather, short day length) and study species (small body size, high daytime foraging rates) that would be expected to favor nocturnal foraging, we found no evidence of nocturnal dive-feeding. Signals from eight radio-tagged Harlequin Ducks never exhibited signal loss due to diving during a total of 780 minutes of nocturnal monitoring. In contrast, the same eight birds exhibited signal loss during 62 ± 7% (SE) of 5-minute diurnal monitoring periods (total of 365 minutes of monitoring). Our results suggest that Harlequin Ducks in south-central Alaska face a stringent time constraint on daytime foraging during midwinter. Harlequin Ducks wintering at high latitudes, therefore, may be particularly sensitive to factors that increase foraging requirements or decrease foraging efficiency.

  15. A mathematical model of the middle and high latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.

    1988-01-01

    A time-dependent three-dimensional model of the middle and high latitude ionosphere is described. The density distributions of six ion species NO(+), O(2+), N(2+), O(+), N(+), He(+), and the electron and ion temperatures are obtained from a numerical solution of the appropriate continuity, momentum, and energy equations. The equations are solved as a function of height for an inclined magnetic field at E and F region altitudes. The three-dimensional nature of the model is obtained by following flux tubes of plasma as they convect or corotate through a moving neutral atmosphere. The model takes account of field-aligned diffusion, cross-field electrodynamic drifts, thermospheric winds, polar wind escape, energy-dependent chemical reactions, neutral composition changes, ion production due to solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow and local heating and cooling processes. The model also takes account of the offset between the geomagnetic and geographic poles.

  16. Recent changes in surface water extent over the Northern latitudes.

    NASA Astrophysics Data System (ADS)

    Papa, F.; Prigent, C.; Rossow, W. B.

    2009-04-01

    All climate scenarios agree on the high sensitivity of the northern regions to global change, with a stronger warming at these latitudes than globally. Continued warming will likely have profound consequences for many continental systems throughout the region. In particular, an increase in air temperature is expected to intensify the Arctic hydrological cycle. As a key parameter of the global biogeochemical and hydrological cycles, terrestrial surface waters (rivers, lakes, man-made reservoirs, wetlands and episodically inundation) are of a particular importance because they interact directly with the ocean and atmosphere. Using a multi-satellite method, including passive microwave land surface emissivities, along with active microwave, visible and near infrared observations developed to estimate inundated area at global scale, we present here the recent changes observed in surface water extent in Northern latitudes over the period 1993-2004. Over these regions, results show a decline in surface water extent with large geographical contrasts between Eurasia and America, between the different large river basins and between the regions underlain or not by permafrost. For six major basins located in Eurasia and North America, we analyze theses changes in comparison with precipitation, temperature and in-situ river discharge variations. The Yenissey and the Lena river basins, which are largely underlain by permafrost, show the largest changes in surface water extent especially in July/August with a decline of about 1-2% per year. Our results support the idea that more deeply thawed permafrost, due to temperature increase in the Boreal regions, would promote increased soil infiltration and a possible shift of water storage from the surface/near surface to the subsurface. The implications of these results in term of energy, biochemical and water cycles will be discussed.

  17. Search for fine scale structures in high latitude solar wind

    NASA Astrophysics Data System (ADS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-06-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  18. Search for fine scale structures in high latitude solar wind

    NASA Technical Reports Server (NTRS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-01-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  19. Turbulent oceanic western-boundary layers at low latitude

    NASA Astrophysics Data System (ADS)

    Quam Cyrille Akuetevi, Cataria; Wirth, Achim

    2013-04-01

    Low latitude oceanic western-boundary layers range within the most turbulent regions in the worlds ocean. The Somali current system with the Great Whirl and the Brazilian current system with its eddy shedding are the most prominent examples. Results from analytical calculations and integration of a one layer reduced-gravity fine resolution shallow water model is used to entangle this turbulent dynamics. Two types of wind-forcing are applied: a remote Trade wind forcing with maximum shear along the equator and a local Monsoon wind forcing with maximum shear in the vicinity of the boundary. For high values of the viscosity (> 1000m2s-1) the stationary solutions compare well to analytical predictions using Munk and inertial layer theory. When lowering the friction parameter time dependence results. The onset of instability is strongly influenced by inertial effects. The unstable boundary current proceeds as a succession of anti-cyclonic coherent eddies performing a chaotic dynamics in a turbulent flow. The dynamics is governed by the turbulent fluxes of mass and momentum. We determine these fluxes by analyzing the (potential) vorticity dynamics. We demonstrate that the boundary-layer can be separated in four sub-layers, which are (starting from the boundary): (1) the viscous sub-layer (2) the turbulent buffer-layer (3) the layer containing the coherent structures and (4) the extended boundary layer. The characteristics of each sub-layer and the corresponding turbulent fluxes are determined, as are the dependence on latitude and the type of forcing. A new pragmatic method of determining the eddy viscosity, based on Munk-layer theory, is proposed. Results are compared to observations and solutions of the multi-level primitive equation model (DRAKKAR).

  20. Improved fire radiative energy estimation in high latitude ecosystems

    NASA Astrophysics Data System (ADS)

    Melchiorre, A.; Boschetti, L.

    2014-12-01

    Scientists, land managers, and policy makers are facing new challenges as fire regimes are evolving as a result of climate change (Westerling et al. 2006). In high latitudes fires are increasing in number and size as temperatures increase and precipitation decreases (Kasischke and Turetsky 2006). Peatlands, like the large complexes in the Alaskan tundra, are burning more frequently and severely as a result of these changes, releasing large amounts of greenhouse gases. Remotely sensed data are routinely used to monitor the location of active fires and the extent of burned areas, but they are not sensitive to the depth of the organic soil layer combusted, resulting in underestimation of peatland greenhouse gas emissions when employing the conventional 'bottom up' approach (Seiler and Crutzen 1980). An alternative approach would be the direct estimation of the biomass burned from the energy released by the fire (Fire Radiative Energy, FRE) (Wooster et al. 2003). Previous works (Boschetti and Roy 2009; Kumar et al. 2011) showed that the sampling interval of polar orbiting satellite systems severely limits the accuracy of the FRE in tropical ecosystems (up to four overpasses a day with MODIS), but because of the convergence of the orbits, more observations are available at higher latitudes. In this work, we used a combination of MODIS thermal data and Landsat optical data for the estimation of biomass burned in peatland ecosystems. First, the global MODIS active fire detection algorithm (Giglio et al. 2003) was modified, adapting the temperature thresholds to maximize the number of detections in boreal regions. Then, following the approach proposed by Boschetti and Roy (2009), the FRP point estimations were interpolated in time and space to cover the full temporal and spatial extent of the burned area, mapped with Landsat5 TM data. The methodology was tested on a large burned area in Alaska, and the results compared to published field measurements (Turetsky et al. 2011).

  1. Comparing High-latitude Ionospheric and Thermospheric Lagrangian Coherent Structures

    NASA Astrophysics Data System (ADS)

    Wang, N.; Ramirez, U.; Flores, F.; Okic, D.; Datta-Barua, S.

    2015-12-01

    Lagrangian Coherent Structures (LCSs) are invisible boundaries in time varying flow fields that may be subject to mixing and turbulence. The LCS is defined by the local maxima of the finite time Lyapunov exponent (FTLE), a scalar field quantifying the degree of stretching of fluid elements over the flow domain. Although the thermosphere is dominated by neutral wind processes and the ionosphere is governed by plasma electrodynamics, we can compare the LCS in the two modeled flow fields to yield insight into transport and interaction processes in the high-latitude IT system. For obtaining thermospheric LCS, we use the Horizontal Wind Model 2014 (HWM14) [1] at a single altitude to generate the two-dimensional velocity field. The FTLE computation is applied to study the flow field of the neutral wind, and to visualize the forward-time Lagrangian Coherent Structures in the flow domain. The time-varying structures indicate a possible thermospheric LCS ridge in the auroral oval area. The results of a two-day run during a geomagnetically quiet period show that the structures are diurnally quasi-periodic, thus that solar radiation influences the neutral wind flow field. To find the LCS in the high-latitude ionospheric drifts, the Weimer 2001 [2] polar electric potential model and the International Geomagnetic Reference Field 11 [3] are used to compute the ExB drift flow field in ionosphere. As with the neutral winds, the Lagrangian Coherent Structures are obtained by applying the FTLE computation. The relationship between the thermospheric and ionospheric LCS is analyzed by comparing overlapping FTLE maps. Both a publicly available FTLE solver [4] and a custom-built FTLE computation are used and compared for validation [5]. Comparing the modeled IT LCSs on a quiet day with the modeled IT LCSs on a storm day indicates important factors on the structure and time evolution of the LCS.

  2. Search for fine scale structures in high latitude solar wind

    NASA Technical Reports Server (NTRS)

    Livi, S.; Parenti, S.; Poletto, G.

    1995-01-01

    About 25 years ago, E. Parker suggested that, as a consequence of the inhomogeneous structure of the corona, the solar wind might consist of adjacent structures with different physical conditions. Since that suggestion was made, the solar wind plasma characteristics have been measured in situ through many experiments, but little has been done to check whether the solar wind shows any evidence for fine scale structures, and, in the affirmative, how far from the Sun these structures persist. A previous work on this subject, by Thieme, Marsch and Schwenn (1990), based on Helios data, lead these authors to claim that the solar wind, between 0.3 and 1 AU, is inhomogeneous on a scale consistent with the hypothesis that the plume-interplume plasmas, at those distances, still retain their identity. In this work we present preliminary results from an investigation of the solar wind fine structure from Ulysses high latitude observations. To this end, we have analyzed data over several months, during 1994, at times well after Ulysses's last encounter with the Heliospheric Current Sheet, when the spacecraft was at latitudes above 50 degrees. These data refer to high speed wind coming from southern polar coronal holes and are best suited for plume-interplume identification. We have performed a power spectra analysis of typical plasma parameters, to test whether the wind plasma consist of two distinct plasma populations. We also examined data to check whether there is any evidence for an horizontal pressure balance over the hypothesized distinct structures. Our results are discussed and compared with previous findings.

  3. A polarized fast radio burst at low Galactic latitude

    NASA Astrophysics Data System (ADS)

    Petroff, E.; Burke-Spolaor, S.; Keane, E. F.; McLaughlin, M. A.; Miller, R.; Andreoni, I.; Bailes, M.; Barr, E. D.; Bernard, S. R.; Bhandari, S.; Bhat, N. D. R.; Burgay, M.; Caleb, M.; Champion, D.; Chandra, P.; Cooke, J.; Dhillon, V. S.; Farnes, J. S.; Hardy, L. K.; Jaroenjittichai, P.; Johnston, S.; Kasliwal, M.; Kramer, M.; Littlefair, S. P.; Macquart, J. P.; Mickaliger, M.; Possenti, A.; Pritchard, T.; Ravi, V.; Rest, A.; Rowlinson, A.; Sawangwit, U.; Stappers, B.; Sullivan, M.; Tiburzi, C.; van Straten, W.; ANTARES Collaboration; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; de Bonis, G.; Distefano, C.; di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Grégoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pǎvǎlaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; van Elewyck, V.; Vivolo, D.; Vizzoca, A.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.; H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Capasso, M.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O'c.; Dubus, G.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hadasch, D.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morâ, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; Reyes, R. De Los; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schulz, A.; Schüssler, F.; Schwanke, U.; Schwemmer, S.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Uchiyama, Y.; Walt, D. J. Van Der; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.

    2017-08-01

    We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 ± 0.8 pc cm-3, a pulse duration of 2.8^{+1.2}_{-0.5} ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7^{+0.2}_{-0.1} Jy. The FRB originated at a Galactic longitude and latitude of 24.66°, 5.28° and 25° away from the Galactic Center. The burst was found to be 43 ± 5 per cent linearly polarized with a rotation measure (RM) in the range -9 < RM < 12 rad m-2 (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X-ray, γ-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.

  4. Heavy negative ions in Titan's ionosphere: Altitude and latitude dependence

    NASA Astrophysics Data System (ADS)

    Coates, A. J.; Wellbrock, A.; Lewis, G. R.; Jones, G. H.; Young, D. T.; Crary, F. J.; Waite, J. H.

    2009-12-01

    One of the unexpected results of the Cassini mission was the discovery of negative ions at altitudes between 950 and 1400 km in Titan's ionosphere with masses up to 10,000 amu/q [Coates, A.J., Crary, F.J., Lewis, G.R., Young, D.T., Waite Jr., J.H., Sittler Jr., E.C., 2007. Discovery of heavy negative ions in Titan's ionosphere. Geophys. Res. Lett., 34, L22103, doi:10.1029/2007GL030978; Waite Jr., J.H., Young, D. T., Coates, A. J., Crary, F. J., Magee, B. A., Mandt, K. E., Westlake, J. H., 2008. The Source of Heavy Organics and Aerosols in Titan's Atmosphere, submitted to Organic Matter in Space, Proceedings IAU Symposium no. 251]. These ions are detected at low altitudes during Cassini's closest Titan encounters by the Cassini plasma spectrometer (CAPS) electron spectrometer. This result is important as it is indicative of complex hydrocarbon and nitrile chemical processes at work in Titan's high atmosphere. They may play a role in haze formation and ultimately in the formation of heavy particles (tholins), which fall through Titan's atmosphere and build up on the surface. During Cassini's prime mission negative ions were observed on 23 Titan encounters, including 7 in addition to those reported by Coates et al. [Coates, A.J., Crary, F.J., Lewis, G.R., Young, D.T., Waite Jr., J.H., Sittler Jr., E.C., 2007. Discovery of heavy negative ions in Titan's ionosphere. Geophys. Res. Lett., 34, L22103, doi:10.1029/2007GL030978]. Here, we also examine the altitude and latitude dependence of the high-mass negative ions observed in Titan's ionosphere, and we examine the implications of these results. We find that the maximum negative ion mass is higher at low altitude and at high latitudes. We also find a weaker dependence of the maximum mass on solar zenith angle.

  5. Comparison of high latitude thermospheric meridional neutral wind climatologies

    NASA Astrophysics Data System (ADS)

    Griffin, Eoghan Michael

    The combination of the long term databases of measurements from the Kiruna Fabry-Perot Interferometer and the EISCAT incoherent scatter radar, both covering more than a solar cycle of data, allows a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. This allows the climatological behaviour of the neutral wind at high latitudes to be investigated, including the influence of both solar activity and season. Two techniques are applied to derive winds from the EISCAT database, one from previous work using the standard technique for incoherent scatter radars, and a new dataset derived using the Meridional Wind Model implementation of servo theory with the EISCAT data as input. The latter technique also uses contemporaneous EISCAT electric field data for correction to the equivalent servo winds. Alongside the local measurements from experiment, model predictions of the behaviour of the winds can also be compared. These have been included and use both empirical sources as in the Horizontal Wind Model and Meridional Wind Model with International Reference Ionosphere input, and also the results from a first principles theoretical model, the UCL Coupled Thermosphere and Ionosphere Model. Comparisons are made between the results from these techniques for each of eight categories corresponding to the four seasons, centred around the equinoxes and solstices, and for two solar activity levels. The detailed comparisons in each case and the implications of the results for the ability of the models to predict the long term behaviour of the winds and also for the degree of agreement between the techniques based on local measurements are discussed. Conclusions are drawn as to the major influences on the climatological behaviour of the wind at this latitude and the possibilities for further work to improve both experimental and modelling efforts.

  6. On the surface composition of Triton's southern latitudes

    NASA Astrophysics Data System (ADS)

    Holler, B. J.; Young, L. A.; Grundy, W. M.; Olkin, C. B.

    2016-03-01

    We present the results of an investigation to determine the longitudinal (zonal) distributions and temporal evolution of ices on the surface of Triton. Between 2002 and 2014, we obtained 63 nights of near-infrared (0.67-2.55 μ m) spectra using the SpeX instrument at NASA's Infrared Telescope Facility (IRTF). Triton has spectral features in this wavelength region from N2, CO, CH4, CO2, and H2O. Absorption features of ethane (C2H6) and 13CO are coincident at 2.405 μ m, a feature that we detect in our spectra. We calculated the integrated band area (or fractional band depth in the case of H2O) in each nightly average spectrum, constructed longitudinal distributions, and quantified temporal evolution for each of the chosen absorption bands. The volatile ices (N2, CO, CH4) show significant variability over one Triton rotation and have well-constrained longitudes of peak absorption. The non-volatile ices (CO2, H2O) show poorly-constrained peak longitudes and little variability. The longitudinal distribution of the 2.405 μ m band shows little variability over one Triton rotation and is 97 ± 44 ° and 92 ± 44 ° out of phase with the 1.58 μ m and 2.35 μ m CO bands, respectively. This evidence indicates that the 2.405 μ m band is due to absorption from non-volatile ethane. CH4 absorption increased over the period of the observations while absorption from all other ices showed no statistically significant change. We conclude from these results that the southern latitudes of Triton are currently dominated by non-volatile ices and as the sub-solar latitude migrates northwards, a larger quantity of volatile ice is coming into view.

  7. Three-dimensional modeling of high-latitude scintillation observations

    NASA Astrophysics Data System (ADS)

    Chartier, Alex; Forte, Biagio; Deshpande, Kshitija; Bust, Gary; Mitchell, Cathryn

    2016-07-01

    Global Navigation Satellite System signals exhibit rapid fluctuations at high and low latitudes as a consequence of propagation through drifting ionospheric irregularities. We focus on the high-latitude scintillation problem, taking advantage of a conjunction of European Incoherent Scatter Radar (EISCAT) observations and a GPS scintillation monitor viewing the same line of sight. Just after 20:00 UT on 17 October 2013, an auroral E region ionization enhancement occurred with associated phase scintillations. This investigation uses the scintillation observations to estimate the ionospheric electron density distribution beyond the spatial resolution of EISCAT (5-15 km along the line of sight in this case). Following the approach of Deshpande et al. (2014), signal propagation is modeled through a specified density distribution. A multiple phase screen propagation algorithm is applied to irregularities conforming to the description of Costa and Kelley (1977) and constrained to match the macroscopic conditions observed by EISCAT. A 50-member ensemble of modeled outputs is approximately consistent with the observations according to the standard deviation of the phase (σp). The observations have σp = 0.23 rad, while the ensemble of modeled realizations has σp = 0.23 + 0.04-0.04. By comparison of the model output with the scintillation observations, we show that the density fluctuations cannot be a constant fraction of the mean density. The model indicates that E region density fluctuations whose standard deviation varies temporally between 5 and 25% of the mean (EISCAT-observed) density are required to explain the observed phase scintillations.

  8. Speciation, Ecological Opportunity, and Latitude (American Society of Naturalists Address).

    PubMed

    Schluter, Dolph

    2016-01-01

    Evolutionary hypotheses to explain the greater numbers of species in the tropics than the temperate zone include greater age and area, higher temperature and metabolic rates, and greater ecological opportunity. These ideas make contrasting predictions about the relationship between speciation processes and latitude, which I elaborate and evaluate. Available data suggest that per capita speciation rates are currently highest in the temperate zone and that diversification rates (speciation minus extinction) are similar between latitudes. In contrast, clades whose oldest analyzed dates precede the Eocene thermal maximum, when the extent of the tropics was much greater than today, tend to show highest speciation and diversification rates in the tropics. These findings are consistent with age and area, which is alone among hypotheses in predicting a time trend. Higher recent speciation rates in the temperate zone than the tropics suggest an additional response to high ecological opportunity associated with low species diversity. These broad patterns are compelling but provide limited insights into underlying mechanisms, arguing that studies of speciation processes along the latitudinal gradient will be vital. Using threespine stickleback in depauperate northern lakes as an example, I show how high ecological opportunity can lead to rapid speciation. The results support a role for ecological opportunity in speciation, but its importance in the evolution of the latitudinal gradient remains uncertain. I conclude that per capita evolutionary rates are no longer higher in the tropics than the temperate zone. Nevertheless, the vast numbers of species that have already accumulated in the tropics ensure that total rate of species production remains highest there. Thus, tropical evolutionary momentum helps to perpetuate the steep latitudinal biodiversity gradient.

  9. Seasonal variation in human illumination exposure at two different latitudes.

    PubMed

    Cole, R J; Kripke, D F; Wisbey, J; Mason, W J; Gruen, W; Hauri, P J; Juarez, S

    1995-12-01

    The authors measured ambient illumination exposure in healthy volunteers in San Diego, California (latitude 32 degrees 43' N, n = 30), and Rochester, Minnesota (latitude 44 degrees 1' N, n = 24), during each of the four quarters of the year, which were centered on the solstices and equinoxes. Subjects wore photosensors on their wrists and lapels (or foreheads while in bed) 24 h per day for an average of 5-6 days per quarter. The maximum of the two illumination readings was stored each minute. Annual average time spent per day in outdoor illumination (> or = 1000 lux) was significantly higher in San Diego than it was in Rochester (p < .04). Daily durations of illumination at or exceeding thresholds of 1, 10, 100, 1000, and 10,000 lux were highly seasonal in the sample as a whole (p < .01 at 1 lux, p < .0001 at other thresholds). Seasonal variation in outdoor illumination was far more pronounced in Rochester than it was in San Diego (interaction p < .001) but remained significant in San Diego (p < or = .03). Seasonal variation in indoor illumination was generally similar in the two cities. The median Rochester subject experienced illumination > or = 1000 lux for 2 h 23 min per day during summer and 23 min per day during winter. The corresponding times in San Diego were 2 h 10 min and 1 h 20 min. Neither age nor gender predicted illumination duration at any level. Both season and geographic location strongly influenced human illumination exposure, and behavior (choice of indoor vs. outdoor environment) was the most important mediating factor.

  10. Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS campaign

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.; Kelley, M. C.; Senior, C.; De La Beaujardiere, O.; Lepping, R.

    1990-01-01

    The electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17-19, 1984 is examined, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. The penetration both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres are studied. The observations in the postmidnight sector are used to compare the longitudinal variations of the zonal perturbation electric field with predictions made from global convection models. The results show that the meridional electric field perturbations are considerably more attenuated with decreasing latitude than the zonal fluctuations. It is concluded that variations in the meridional electric field at low latitudes are largely due to dynamo effects.

  11. Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS campaign

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.; Kelley, M. C.; Senior, C.; De La Beaujardiere, O.; Lepping, R.

    1990-01-01

    The electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17-19, 1984 is examined, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. The penetration both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres are studied. The observations in the postmidnight sector are used to compare the longitudinal variations of the zonal perturbation electric field with predictions made from global convection models. The results show that the meridional electric field perturbations are considerably more attenuated with decreasing latitude than the zonal fluctuations. It is concluded that variations in the meridional electric field at low latitudes are largely due to dynamo effects.

  12. Types of case series--the anatomically based approach: commentary on M. F. Schwartz & G. S. Dell: case series investigations in cognitive neuropsychology.

    PubMed

    Shallice, Tim; Buiatti, Tania

    2011-10-01

    The paper addresses a weakness in the Schwartz and Dell paper (2010)-namely, its discussion of the inclusion criteria for case series. The paper distinguishes the different types that exist and how they constrain the theoretical conclusions that one can draw about the organization of the normal cognitive system. Four different types of inclusion criteria are considered. Two are those treated by Schwartz and Dell-namely, theoretically derived clinical criteria, such as the example of semantic dementia, and broad clinical criteria such as the presence of aphasia. In addition, in the present paper two different types of anatomically based criteria are assessed-those using anatomical regions selected a priori and also regions selected as a result of an anatomical group study analysis. Putative functional syndromes are argued to be the empirical building blocks for cognitive neuropsychology. Anatomically based case series can aid in their construction or in their fractionation.

  13. Determination of solar proton fluxes and energies at high solar latitudes by UV radiation measurements

    NASA Technical Reports Server (NTRS)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The latitudinal variation of the solar proton flux and energy causes a density increase at high solar latitudes of the neutral gas penetrating the heliosphere. Measurements of the neutral density by UV resonance radiation observations from interplanetary spacecraft thus permit deductions on the dependence of the solar proton flux on heliographic latitude. Using both the results of Mariner 10 measurements and of other off-ecliptic solar wind observations, the values of the solar proton fluxes and energies at polar heliographic latitudes are determined for several cases of interest. The Mariner 10 analysis, together with IPS results, indicate a significant decrease of the solar proton flux at polar latitudes.

  14. ROTATION RATE DIFFERENCES OF POSITIVE AND NEGATIVE SOLAR MAGNETIC FIELDS BETWEEN ±60° LATITUDES

    SciTech Connect

    Shi, X. J.; Xie, J. L.

    2015-04-15

    Based on a cross-correlation analysis of the Carrington synoptic maps of solar photospheric magnetic fields from Carrington Rotations Nos. 1625 to 2135 (from 1975 February to 2013 March), the sidereal rotation rates of the positive and negative magnetic fields in the latitude range of ±60° are obtained, and the rotation rate differences between them are investigated. The time–latitude distribution of the rate differences is shown, which looks like a butterfly diagram at the low and middle latitudes. For comparison, the time–latitude distribution of the longitudinally averaged photospheric magnetic fields is shown. We conclude that the magnetic fields having the same polarity as the leading sunspots at a given hemisphere rotate faster than those exhibiting the opposite polarity at low and middle latitudes. However, at higher latitudes, the magnetic fields having the same polarity as the leading sunspots at a given hemisphere do not always rotate faster than those with the opposite polarity. Furthermore, the relationship between the rotation rate differences and solar magnetic fields is studied through a correlation analysis. Our result shows that the correlation coefficients between them reach maximum values at 13° (14°) latitude in the northern (southern) hemisphere, and change sign at 28° latitude in both hemispheres, then reach their minimum values at 58° (53°) latitude in the northern (southern) hemisphere.

  15. Determination of solar proton fluxes and energies at high solar latitudes by UV radiation measurements

    NASA Technical Reports Server (NTRS)

    Witt, N.; Blum, P. W.; Ajello, J. M.

    1981-01-01

    The latitudinal variation of the solar proton flux and energy causes a density increase at high solar latitudes of the neutral gas penetrating the heliosphere. Measurements of the neutral density by UV resonance radiation observations from interplanetary spacecraft thus permit deductions on the dependence of the solar proton flux on heliographic latitude. Using both the results of Mariner 10 measurements and of other off-ecliptic solar wind observations, the values of the solar proton fluxes and energies at polar heliographic latitudes are determined for several cases of interest. The Mariner 10 analysis, together with IPS results, indicate a significant decrease of the solar proton flux at polar latitudes.

  16. A new species of the South East Asian genus Sarax Simon, 1892 (Arachnida: Amblypygi: Charinidae) and synonymization of Sarax mediterraneus Delle Cave, 1986.

    PubMed

    Seiter, Michael; Wolff, Jonas; Hörweg, Christoph

    2015-09-04

    A new species of the whip spider genus Sarax Simon, 1892 from Cebu Island in the Philippines is described: Sarax huberi sp. nov. With the description of this species, the diversity of the genus is increased to three species in the Philippines. Some additional data on their natural environment and their specific habitat are presented and compared with sibling species. The synonymization of Sarax mediterraneus Delle Cave, 1986 with Sarax buxtoni (Gravely, 1915) is carried out.

  17. High latitude hydrological changes during the Eocene Thermal Maximum 2

    NASA Astrophysics Data System (ADS)

    Krishnan, Srinath; Pagani, Mark; Huber, Matthew; Sluijs, Appy

    2014-10-01

    -enriched signals at the base of the event, including (1) intense local drying and cooling leading to evaporative 2H-enrichment; (2) changes in frequency/intensity of storm events and its impact on high latitude amount effects; and (3) changes in low-latitude temperatures. Evidence for hydrological shifts at the base of both hyperthermals suggests that hydrological change or the factors promoting hydrological change played a role in triggering the release of greenhouse gases. Generation of similar high-resolution isotopic- and temperature records at other latitudes is crucial for understanding the causal links between temperature and hydrological changes and may help constrain the source and mechanism of carbon release that triggered the early Eocene hyperthermals.

  18. The spectral nature of Titan's mid-latitude region

    NASA Astrophysics Data System (ADS)

    Solomonidou, Anezina; Coustenis, Athena; Lopes, Rosaly; Malaska, Michael; Rodriguez, Sebastien; Drossart, Pierre; Schmitt, Bernard; Philippe, Sylvain; Janssen, Michael; Le Gall, Alice; Lawrence, Kenneth; Hirtzig, Mathieu; Sohl, Frank; Stephan, Katrin; Jaumann, Ralf; Brown, Robert; Villanueva, Edward; Bratsolis, Emmanuel; Matsoukas, Christos; Schoenfeld, Ashley

    2017-04-01

    We infer surface properties, such as surface albedo and atmospheric contributions in the form of haze content, of the mid-latitude region of Titan. In previous studies [1;2] we reported results on two areas presenting indications for possible changes in surface albedo with time [2]. We also investigate the endogenic or exogenic processes linked to the formation of the various mid-latitude geomorphological units. These could be aeolian, fluvial, sedimentary, cryovolcanic, lacustrine, and more. Furthermore, deposition of organics through the atmosphere seems to be predominantly present [1]. We now focus on constraining the chemical composition of the various geomorphological units [5;6] by investigating the lower atmosphere of Titan from Visual and Infrared Mapping Spectrometer (VIMS) spectro-imaging data by use of a recently updated radiative transfer code in the near-IR range. For the distinction of geomorphological units we use RADAR/SAR data [4]. We study the units of interest identified in [1;3] and [4]: mountains, plains, labyrinths, dune fields, and possible cryovolcanic and/or evaporitic features (the latter two are albedo features, [4;5]). Our findings indicate that many of the regions from the same geomorphological unit show compositional variations depending on location, while units of significant geomorphological differences seem to consist of very similar material mixtures. Preliminary results on the chemical composition of the regions that have shown temporal changes (i.e. Tui Regio and Sotra Patera; [6]) are also presented. The albedo differences and similarities among the various geomorphological terrains set constraints on the possible geological processes that govern Titan's surface. References: [1] Lopes, R.M.C., et al.: Icarus, 270, 162-182, 2016; [2] Solomonidou, A., et al.: Icarus, 270, 85-99, 2016; [3] Lopes, R.M.C., et al.: Icarus, 205, 540-558, 2010; [4] Malaska, M., et al.: Icarus, 270, 130-161, 2016; [4] Barnes, J., et al.: Pl. Scie., 2

  19. Autonomous, continuously recording broadband seismic stations at high-latitude

    NASA Astrophysics Data System (ADS)

    Beaudoin, B.; Parker, T.; Bonnett, B.; Tytgat, G.; Anderson, K.; Fowler, J.

    2009-04-01

    IRIS PASSCAL is in the third year of an NSF funded development and acquisition effort to establish a pool of cold-hardened seismic stations specifically for high-latitude broadband deployments. We have two complete years of field trials and have successfully recorded continuous seismic data during both years with data recovery rates of ~90%. Our design is premised on a 2W autonomous system recording to local media, capable of lasting two years without service. The system is composed of four new design elements: a heavily insulated station enclosure; a state-of-health (SOH) Iridium modem; a light weight, easily deployed solar panel mount; and a power system that includes power switching between primary (Lithium Thionyl Chloride) and secondary batteries. The station enclosures have proved most critical in keeping our data acquisition systems operating within manufacturer specifications and primary batteries within a 50-70% efficiency range. Enclosures with 2.5cm-thick vacuum panels and 5cm of foam insulation have kept interior enclosure temperatures 25-30°C above background (typically below -50°C). This austral summer we are deploying version three of our enclosures. Significant changes in the design include thicker vacuum panels (5cm), more robust construction, and simplified cable routing. An important aspect of our station design is easy installation and minimal weight. To simplify installation our station enclosures are packed with datalogger, SOH communications and batteries in the lab or base camp, so that access to the internal components is not necessary at the remote site. Bulkhead connectors allow a user to fully interact with the system without ever having to open the enclosure. Solar panel mounts are also fully constructed prior to deployment. Once on site, digging two large holes (one for the enclosure and one for the broadband seismometer) and constructing the site takes roughly 2 hours. A station designed to record continuously for 12-14 months is

  20. Exposed Ice in the Northern Mid-Latitudes of Mars

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.

    2007-01-01

    Ice-Rich Layer: Polygonal features with dimensions of approximately 100 meters, bounded by cracks, are commonly observed on the martian northern plains. These features are generally attributed to thermal cracking of ice-rich sediments, in direct analogy to polygons in terrestrial polar regions. We mapped polygons in the northern mid-latitudes (30 to 65 N) using MOC and HiRISE images. Polygons are scattered across the northern plains, with a particular concentration in western Utopia Planitia. This region largely overlaps the Late Amazonian Astapus Colles unit, characterized by polygonal terrain and nested pits consistent with periglacial and thermokarst origins. Bright and Dark Polygonal Cracks: An examination of all MOC images (1997 through 2003) covering the study area demonstrated that, at latitudes of 55 to 65 N, most of the imaged polygons show bright bounding cracks. We interpret these bright cracks as exposed ice. Between 40 and 55 N, most of the imaged polygons show dark bounding cracks. These are interpreted as polygons from which the exposed ice has been removed by sublimation. The long-term stability limit for exposed ice, even in deep cracks, apparently lies near 55 N. Bright and Dark Spots: Many HiRISE and MOC frames showing polygons in the northern plains also show small numbers of bright and dark spots, particularly in western Utopia Planitia. Many of the spots are closely associated with collapse features suggestive of thermokarst. The spots range from tens to approximately 100 meters in diameter. The bright spots are interpreted as exposed ice, due to their prevalence on terrain mapped as ice rich. The dark spots are interpreted as former bright spots, which have darkened as the exposed ice is lost by sublimation. The bright spots may be the martian equivalents of pingos, ice-cored mounds found in periglacial regions on Earth. Terrestrial pingos from which the ice core has melted often collapse to form depressions similar to the martian dark spots

  1. Numerical modeling of Atlantic hurricanes moving into the middle latitudes

    NASA Astrophysics Data System (ADS)

    Fogarty, Christopher T.

    Hurricanes that form over the Atlantic Ocean very frequently migrate into the middle latitudes where they encounter very different oceanic and atmospheric conditions than in the tropics. Cool sea surface temperatures (SSTs) cause these storms to weaken and become thermodynamically decoupled from the ocean, while baroclinic atmospheric environments often cause them to transform into extratropical storms---a process known as extratropical transition (ET). The changing structure of these storms in the middle latitudes presents many unique forecasting challenges related to the increasing asymmetry in moisture and wind fields, and their potentially destructive nature. An examination of three such events over Eastern Canada---using a combination of observations and a numerical model---forms the foundation of this work, with an emphasis on applying the research to weather forecasting. The case studies include Hurricane Michael (2000), Hurricane Karen (2001) and Hurricane Juan (2003). Hurricane Michael intensified in a strongly-baroclinc environment and evolved into an intense extratropical storm over Newfoundland. Karen also underwent ET, but weakened quickly during its approach to Nova Scotia, while Hurricane Juan struck the province as a category-two hurricane, experiencing only marginal weakening over anomalously warm SSTs. In essence, these cases represent a cross section of the behavior of many tropical cyclones in this part of the world. Hindcast simulations are conducted for each event using the Canadian Mesoscale Compressible Community (MC2) model with a synthetic, observationally-consistent hurricane vortex used in the model's initial conditions. Sensitivity experiments are run for each case by modifying initial specifications of the vortex, model physics parameterizations, and surface boundary conditions like SST. In the case of Hurricane Juan, it is determined that the anomalously-warm SSTs played a significant role in the landfall intensity, while Hurricane

  2. Statistical studies of impulsive events at high latitudes

    NASA Technical Reports Server (NTRS)

    Lin, Z. M.; Bering, E. A.; Benbrook, J. R.; Liao, B.; Lanzerotti, L. J.; Maclennan, C. G.; Wolfe, A. N.; Friis-Christensen, E.

    1995-01-01

    A statistical study has been made of the high-latitude impulsive events that were observed during the 1985-1986 South Pole Balloon Campaign. The events were selected by searching for unipolar pulses greater than or equal to 10 nT above background in the vertical component of the magnetic field on the ground and/or pedestal or 'W' shaped horizontal electric field perturbations greater than or equal to 10 mV/m in amplitude and accompanied by perturbations in the vertical electric field at balloon altitude. A main event list comprising 112 events was compiled from the 468 hours of data available. Three aspects of the events were examined: the solar wind conditions prior to the event, local time of observation, and intrinsic properties of the events. The local time distribution was obtained from the 112 entry main event list and was found to be nearly uniform across the dayside, with no midday gap. The event rate found using our low-amplitude selection criteria was 0.7 event/hr, comparable to expectations based on in situ studies of the magnetopause. A total of 42 events were found for which data were available from Interplanetary Monitoring Platform (IMP) 8. Of these events, 12 occurred when the Z(sub GSM) component (B(sub Z)) of the interplanetary magnetic field (IMF) was northward and 30 occurred when B(sub Z) was southward or fluctuating. Only three of the B(sub Z) northward cases and only five of the B(sub Z) southward cases were preceded by pressure pulses greater than 0.4 nPa in amplitude. Ten of the events were studied in detail by means of a model-fitting method discussed elsewhere. This method infers values of several parameters, including the total current flowing in a coaxial or monopole system and a two-dimensional dipole system. The intrinsic properties of the events showed that only approximately 10% of the total current contributed to momentum transfer to the high-latitude ionosphere, that the direction of the motion depended more on local time of

  3. Study of the seasonal ozone variations at European high latitudes

    NASA Astrophysics Data System (ADS)

    Werner, R.; Stebel, K.; Hansen, H. G.; Hoppe, U.-P.; Gausa, M.; Kivi, R.; von der Gathen, P.; Orsolini, Y.; Kilifarska, N.

    2011-02-01

    The geographic area at high latitudes beyond the polar circle is characterized with long darkness during the winter (polar night) and with a long summertime insolation (polar day). Consequentially, the polar vortex is formed and the surrounding strong polar jet is characterized by a strong potential vorticity gradient representing a horizontal transport barrier. The ozone dynamics of the lower and middle stratosphere is controlled both by chemical destruction processes and transport processes.To study the seasonal ozone variation at high latitudes, ozone vertical distributions are examined, collected from the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (69.3°N, 16.0°E,) station at Andenes and from the stations at Sodankylä (67.4°N, 26.6°E) and at Ny-Ålesund (78.9°N, 11.9°E). The data sets cover the time period from 1994 until 2004. We find a second ozone maximum near 13-15 km, between the tropopause and the absolute ozone maximum near 17-20 km. The maximum is built up by the combination of air mass transport and chemical ozone destruction, mainly caused by the NOx catalytic cycle, which begins after the polar night and intensifies with the increasing day length. Formation of a troposphere inversion layer is observed. The inversion layer is thicker and reaches higher altitudes in winter rather than in summer. However, the temperature inversion during summer is stronger. The formation of an enhanced ozone number density is observed during the spring-summer period. The ozone is accumulated or becomes poor by synoptic weather patterns just above the tropopause from spring to summer. In seasonal average an ozone enhancement above the tropopause is obtained.The stronger temperature inversion during the summer period inhibits the vertical stratosphere-troposphere exchange. The horizontal advection in the upper troposphere and lower stratosphere is enforced during summer. The combination of these mechanisms generates a layer with a very low

  4. Paleoclimate records at high latitude in Arctic during the Paleogene

    NASA Astrophysics Data System (ADS)

    Salpin, Marie; Schnyder, Johann; Baudin, François; Suan, Guillaume; Labrousse, Loïc; Popescu, Speranta; Suc, Jean-Pierre

    2015-04-01

    Paleoclimate records at high latitude in Arctic during the Paleogene SALPIN Marie1,2, SCHNYDER Johann1,2, BAUDIN François1,2, SUAN Guillaume3, LABROUSSE Loïc1,2, POPESCU Speranta4, SUC Jean-Pierre1,4 1: Sorbonne Universités, UPMC Univ Paris 06, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005, Paris, France 2: CNRS, UMR 7193, Institut des Sciences de la Terre Paris (iSTeP), F 75005 Paris, France 3: UCB Lyon 1, UMR 5276, LGLTPE, 69622 Villeurbanne Cedex, France 4: GEOBIOSTRATDATA.CONSULTING, 385 Route du Mas Rillier 69140 Rillieux la Pape, France The Paleogene is a period of important variations of the Earth climate system either in warming or cooling. The climatic optima of the Paleogene have been recognized both in continental and marine environment. This study focus on high latitudes of the northern hemisphere, in the Arctic Basin. The basin has had an influence on the Cenozoic global climate change according to its polar position. Is there a specific behaviour of the Arctic Basin with respect to global climatic stimuli? Are there possible mechanisms of coupling/decoupling of its dynamics with respect to the global ocean? To answer these questions a unique collection of sedimentary series of Paleogene age interval has been assembled from the Laurentian margin in Northern Yukon (Canada) and from the Siberian margin (New Siberian Islands). Selected continental successions of Paleocene-Eocene age were used to study the response of the Arctic system to known global events, e.g. the climatic optima of the Paleogene (the so-called PETM, ETM2 or the Azolla events). Two sections of Paleocene-Eocene age were sampled near the Mackenzie delta, the so-called Coal Mine (CoMi) and Caribou Hills (CaH) sections. The aim of the study is to precise the climatic fluctuations and to characterise the source rock potential of the basin, eventually linked to the warming events. This study is based on data of multi-proxy analyses: mineralogy on bulk and clay

  5. Spaced direction finding of nighttime whistlers at low and equatorial latitudes and their propagation mechanism

    SciTech Connect

    Hayakawa, M. ); Ohta, K. ); Shimakura, S. )

    1990-09-01

    The propagation mechanism of low-latitude and equatorial latitude whistlers is investigated on the basis of spaced direction finding measurements in South China. Two major occurrence peaks on January 5 and January 6 and two minor ones on January 9 and January 11 have been analyzed and the following experimental results have emerged. (1) The whistler occurrence at very low latitudes is generally very small compared with that at low latitude (geomagnetic latitude {approx gt} 20{degree}), but once it occurs, the occurrence rate becomes comparable to that at low latitudes. (2) The whistler dispersion is single-valued at any particular local time. (3) The ionospheric exit region of whistlers is very much restricted to the geomagnetic latitude range of 10{degree}-14{degree}, and there are no observed whistlers whose path latitude is between 14{degree} and 20{degree}. (4) The extent of their ionospheric exit region is very stable on different days, and the radius of the distribution is less than 40-50 km. (5) Surprisingly high occurrence of echo train whistlers is observed. (6) The propagation of whistlers in the Earth-ionosphere waveguide after ionospheric transmission is more likely toward higher latitudes than toward the equator and the subionospheric propagation seems to exhibit a horizontal beaming around the magnetic meridian plane. The authors attempt to itnerpret these characteristics of the observations in terms of either nonducted or field-aligned propagation, but discussion indicates that especially findings 4 and 5 are strongly indicative of field-aligned propagation for very low latitude whistlers localized in geomagnetic latitudes of 10{degree}-14{degree}.

  6. The tropopause at southern extratropical latitudes: Argentine operational rawinsonde climatology

    NASA Astrophysics Data System (ADS)

    Bischoff, Susana A.; Canziani, Pablo O.; Yuchechen, Adrián E.

    2007-02-01

    Argentine operational rawinsonde records spanning a 30-year period (1968-1997) were used to study the climatology of the tropopause from the subtropics to the southern mid-latitudes, approximately along the 60°W meridian. The thermal tropopause annual cycle as well as its variability was analyzed at three sites: Resistencia (RES), Ezeiza (EZE), and Comodoro Rivadavia (CRD). Single and double tropopause observations were studied, given the comparatively frequent occurrence of double tropopause events at all three sites. The tropopause behavior at RES and CRD is distinct, whereas at EZE it shows a winter evolution similar to the one at CRD and a summer evolution closer to the one at RES, in agreement with the annual evolution of the subtropical jet. The tropopause evolution is discussed under the light of the dynamic climatology of southern South America. In the presence of double tropopause events and in terms of potential temperature, it should be noted that the upper tropopause temperature is close to the 380 K isentropic, i.e. the tropical tropopause layer. Moreover, the lower tropopause and single tropopause events are fairly close together, i.e. coincident with the lowermost stratosphere. Considering previous research and results from the present analysis, a definition of Extratropical Tropopause Layer (ExTL) is introduced in this work. It is proposed that the lowermost stratosphere should be regarded as the ExTL.

  7. Analysis of the atmospheric upward radiation in low latitude area

    NASA Astrophysics Data System (ADS)

    Li, Haiying; Wu, Zhensen; Lin, Leke; Lu, Changsheng

    2016-10-01

    Remote sensing using THz wave has irreplaceable advantage comparing to the microwave and the infrared waves, and study on the THz remote sensing become more and more popular in recent years. The major applications of the remote sensing in THz wavelengths are the retrieval of the atmospheric parameters and the microphysical information of the ice cloud. The remote sensing of the atmosphere is based on the radiation of THz wave along the earth-space path of which the most significant part is the upward radiation of the atmosphere. The upward radiation of the atmosphere in sunny day in the low latitude area is computed and analyzed in this paper. The absorption of THz wave by the atmosphere is calculated using the formulations illustrated in the Recommendation ITU-R P.676 to save machine hour, the frequency range is then restricted below 1THz. The frequencies used for the retrieval of atmospheric parameters such as temperature and water content are usually a few hundred GHz, at the lower end of THz wavelengths, so this frequency range is sufficient. The radiation contribution of every atmospheric layer for typical frequencies such as absorption window frequencies and peak frequencies are analyzed. Results show that at frequencies which absorption is severe, information about lower atmosphere cannot reach the receiver onboard a satellite or other high platforms due to the strong absorption along the path.

  8. Seasonal dynamics of meroplankton in a high-latitude fjord

    NASA Astrophysics Data System (ADS)

    Michelsen, Helena Kling; Svensen, Camilla; Reigstad, Marit; Nilssen, Einar Magnus; Pedersen, Torstein

    2017-04-01

    Knowledge on the seasonal timing and composition of pelagic larvae of many benthic invertebrates, referred to as meroplankton, is limited for high-latitude fjords and coastal areas. We investigated the seasonal dynamics of meroplankton in the sub-Arctic Porsangerfjord (70°N), Norway, by examining their seasonal changes in relation to temperature, chlorophyll a and salinity. Samples were collected at two stations between February 2013 and August 2014. We identified 41 meroplanktonic taxa belonging to eight phyla. Multivariate analysis indicated different meroplankton compositions in winter, spring, early summer and late summer. More larvae appeared during spring and summer, forming two peaks in meroplankton abundance. The spring peak was dominated by cirripede nauplii, and late summer peak was dominated by bivalve veligers. Moreover, spring meroplankton were the dominant component in the zooplankton community this season. In winter, low abundances and few meroplanktonic taxa were observed. Timing for a majority of meroplankton correlated with primary production and temperature. The presence of meroplankton in the water column through the whole year and at times dominant in the zooplankton community, suggests that they, in addition to being important for benthic recruitment, may play a role in the pelagic ecosystem as grazers on phytoplankton and as prey for other organisms.

  9. Map of Martian Iron at Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This gamma ray spectrometer map of the mid-latitude region of Mars is based on gamma-rays from the element iron. Iron, having the chemical symbol Fe, is among of the most abundant elements on the surface of both Mars and Earth. It is responsible for the red color on the surface of Mars. Regions of highest iron content, shown in red, are concentrated in the area spanning from Utopia Planitia to Amazonis Planitia (right and left sides of the map) and within Acidalia Planitia (just left of center). Contours of constant surface elevation are also shown. The long continuous contour line running from east to west marks the approximate separation of the younger lowlands in the north from the older highlands in the south.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The gamma ray spectrometer was provided by the University of Arizona, Tucson. Lockheed Martin Astronautics, Denver, Colo., is the prime contractor for the 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.

  10. Paleoclimatic significance of high-latitude loess deposits

    SciTech Connect

    Beget, J.E.

    1992-03-01

    Loess deposits reflect changing environmental conditions in terrestrial regions, and contain long paleoclimatic records analogous to those found in marine sediments, lacustrine sediments, and ice sheets. Alaskan loess was deposited at rates of ca. 0.05-0.5 mm yr-l during the last 2-3 x 106 years; loess deposits contain some of the longest and most complete proxy climate records yet found. New analytical methods are used to reconstruct changes in climate and atmospheric regime including wind intensity, storminess, temperature, and precipitation. Loess also contains a history of permafrost and paleosol formation, volcanic eruptions, and paleoecologic changes in high latitude regions, as well as Quaternary fossils and early man sites and artifacts. Time-series analysis of proxy climate data from loess supports the astronomic model of climate change, although some transient climate events recorded in loess records are too short to be explained by orbital insolation forcing, and may instead correlate with rapid, short-term changes in atmospheric C02 and CH4 content.

  11. The Low-latitude Ionospheric Sensor Network (LISN): Initial Measurements

    NASA Astrophysics Data System (ADS)

    Valladares, C. E.

    2008-12-01

    This paper describes the characteristics and illustrates the early measurements of the first distributed observatory that is being installed in the South American region to study the low-latitude ionosphere and upper atmosphere. The LISN distributed observatory will be comprised of nearly 70 GPS receivers with the capability to measure Total Electron Content (TEC), amplitude and phase scintillation and Traveling Ionospheric Disturbances (TIDs). The network will include 5 ionosondes able to measure nighttime E-region densities and 5 collocated magnetometers that will be placed along the same magnetic meridian. This network of GPS receivers and ionospheric sensors span from north to south in the South American continent west of the 55o West meridian. In addition to introducing the present capabilities of the LISN network, this paper will present the results of the first LISN campaign dedicated to detect medium-scale (~100 km) TIDs that was conducted at Huancayo using 3 closely-spaced GPS receivers. This paper also presents initial calculations of the vertical drift velocity using 3 magnetometers, two of them placed off the equator in opposite hemispheres and a detailed description of the measurements of the first LISN ionosonde that is presently operating near the magnetic equator.

  12. What Drives the Variability of the Mid-Latitude Ionosphere?

    NASA Astrophysics Data System (ADS)

    Goncharenko, L. P.; Zhang, S.; Erickson, P. J.; Harvey, L.; Spraggs, M. E.; Maute, A. I.

    2016-12-01

    The state of the ionosphere is determined by the superposition of the regular changes and stochastic variations of the ionospheric parameters. Regular variations are represented by diurnal, seasonal and solar cycle changes, and can be well described by empirical models. Short-term perturbations that vary from a few seconds to a few hours or days can be induced in the ionosphere by solar flares, changes in solar wind, coronal mass ejections, travelling ionospheric disturbances, or meteorological influences. We use over 40 years of observations by the Millstone Hill incoherent scatter radar (42.6oN, 288.5oE) to develop an updated empirical model of ionospheric parameters, and wintertime data collected in 2004-2016 to study variability in ionospheric parameters. We also use NASA MERRA2 atmospheric reanalysis data to examine possible connections between the state of the stratosphere & mesosphere and the upper atmosphere (250-400km). A case of major SSW of January 2013 is selected for in-depth study and reveals large anomalies in ionospheric parameters. Modeling with the NCAR Thermospheric-Ionospheric-Mesospheric-Electrodynamics general Circulation Model (TIME-GCM) nudged by WACCM-GEOS5 simulation indicates that during the 2013 SSW the neutral and ion temperature in the polar through mid-latitude region deviates from the seasonal behavior.

  13. Inner Plasma Structure of the Low-Latitude Reconnection Layer

    NASA Technical Reports Server (NTRS)

    Zhang, Q.-H.; Dunlop, M. W.; Lockwood, M.; Lavraud, B.; Bogdanova, Y. V.; Hasegawa, H.; Yang, H. -G.; Liu, R. -Y.; Hu, H. -Q.; Zhang, B. -C.; hide

    2012-01-01

    We report a clear transition through a reconnection layer at the low-latitude magnetopause which shows a complete traversal across all reconnected field lines during northwestward interplanetary magnetic field (IMF) conditions. The associated plasma populations confirm details of the electron and ion mixing and the time history and acceleration through the current layer. This case has low magnetic shear with a strong guide field and the reconnection layer contains a single density depletion layer on the magnetosheath side which we suggest results from nearly field-aligned magnetosheath flows. Within the reconnection boundary layer, there are two plasma boundaries, close to the inferred separatrices on the magnetosphere and magnetosheath sides (Ssp and Ssh) and two boundaries associated with the Alfvén waves (or Rotational Discontinuities, RDsp and RDsh). The data are consistent with these being launched from the reconnection site and the plasma distributions are well ordered and suggestive of the time elapsed since reconnection of the field lines observed. In each sub-layer between the boundaries the plasma distribution is different and is centered around the current sheet, responsible for magnetosheath acceleration. We show evidence for a velocity dispersion effect in the electron anisotropy that is consistent with the time elapsed since reconnection. In addition, new evidence is presented for the occurrence of partial reflection of magnetosheath electrons at the magnetopause current layer.

  14. Preface: The International Reference Ionosphere (IRI) at equatorial latitudes

    NASA Astrophysics Data System (ADS)

    Reinisch, Bodo; Bilitza, Dieter

    2017-07-01

    This issue of Advances in Space Research includes papers that report and discuss improvements of the International Reference Ionosphere (IRI). IRI is the international standard for the representation of the plasma in Earth's ionosphere and recognized as such by the Committee on Space Research (COSPAR), the International Union of Radio Science (URSI), the International Telecommunication Union (ITU), and the International Standardization Organization (ISO). As requested, particularly by COSPAR and URSI, IRI is an empirical model relying on most of the available and reliable ground and space observations of the ionosphere. As new data become available and as older data sources are fully exploited the IRI model undergoes improvement cycles to stay as close to the existing data record as possible. The latest episode of this process is documented in the papers included in this issue using data from the worldwide network of ionosondes, from a few of the incoherent scatter radars, from the Alouette and ISIS topside sounders, and from the Global Navigation Satellite Systems (GNSS). The focus of this issue is on the equatorial and low latitude region that is of special importance for ionospheric physics because it includes the largest densities and steep density gradients in the double hump latitudinal structure, the Equatorial Ionization Anomaly (EIA), which is characteristic for this region.

  15. Surface changes in mid-latitude regions on Titan

    NASA Astrophysics Data System (ADS)

    Solomonidou, A.; Coustenis, A.; Lopes, R. M. C.; Hirtzig, M.; Rodriguez, S.; Stephan, K.; Sotin, C.; Drossart, P.; Lawrence, K.; Le Mouélic, S.; Bratsolis, E.; Jaumann, R.; Brown, R. H.; Malaska, M.

    2014-04-01

    We present a study focused on the mid-latitude and close to the equator surface regions on Titan that present an interest on their spectral behavior and/or morphology. These are regions where spectroscopic anomalies have been reported in the evolution of the brightness and several interpretations have been proposed (cryovolcanic candidates, evaporates, lacustrine, etc [1;2;5]). Also in our work here we have included analysis of some undifferentiated plains (also referred to as 'blandlands'), which are vast expanses of terrains that appear bland in the radar data [3]. By applying a Radiative transfer code [4;2] we have analyzed these regions to look for evolution with time through their spectral behavior. We use as reference point and calibration tool the surface albedo retrieval of the Huygens Landing site (Titan's ground truth) and we also check the variability of the surface albedo of these regions against areas that are not expected to change with time (e.g. dune fields), by retrieving their albedo differences at all wavelengths [2]. We report here surface albedo changes with time for some of these regions of interest that imply connection to exogenic and/or endogenic processes.

  16. Ionospheric mid-latitude response to solar wind discontinuities

    NASA Astrophysics Data System (ADS)

    Munteanu, Costel; Mosna, Zbysek; Kouba, Daniel; Echim, Marius

    2013-04-01

    We have compiled a database of 356 discontinuities detected by both the Advanced Composition Explorer ACE) and Cluster satellites in the solar wind between 2001-2012 and analyzed their ionospheric response. Each discontinuity of the data base is defined by a change of at least 5 nT in less than 5 min in one or more components of the interplanetary magnetic field (IMF). The discontinuities are observed in January-April every year, when Cluster enters the solar wind. The ionospheric effects of solar wind discontinuities are investigated by checking the variations of critical frequencies foF2, the heights of the F layer and the ionospheric plasma dynamics recorded using ground measurement with a time resolution of 15 minutes from mid-latitude digisondes located in Czech Republic. The time delay between solar wind input and the ionospheric response is analyzed using the characteristics and the shape of the ionograms. The geoeffectiveness of the solar wind discontinuities is expressed as correlation between key plasma parameters (e,g, the solar wind velocity, magnetic jump across the discontinuity) and the ionospheric variations. Solar cycle effects are also discussed.

  17. Mathematical modeling of plasma drifts over equatorial low latitude regions

    NASA Astrophysics Data System (ADS)

    Sundaresan, S.; Nageswara Rao, B.

    2010-09-01

    This paper presents a mathematical model to simulate ionospheric plasma drifts at equatorial low latitude regions by coupling of E- and F-regions. The governing non-linear differential equations (of elliptic and parabolic nature) are solved numerically through finite-difference schemes and obtained neutral winds and electric fields. The temperature and electron density profiles are generated utilizing MSIS-86 atmospheric model. The continuity equation is employed to obtain night-time E-region density profile using measured ionograms at Trivandrum (India). The computed vertical and zonal plasma drifts are comparable with measured Jacamarca plasma drifts with little variations during noon and evening times. The plasma drifts at Trivandrum (8.5° N, 76.5° E, dip 0.5° N) are compared with those of Jicamarca (12° S, 76.9° W, dip 2° N). Neutral wind simulations of present model agree well with those of horizontal wind model (HWM-93). The post-sunset enhancement and its reversal are also discussed.

  18. Does fish larval dispersal differ between high and low latitudes?

    PubMed Central

    Leis, Jeffrey M.; Caselle, Jennifer E.; Bradbury, Ian R.; Kristiansen, Trond; Llopiz, Joel K.; Miller, Michael J.; O'Connor, Mary I.; Paris, Claire B.; Shanks, Alan L.; Sogard, Susan M.; Swearer, Stephen E.; Treml, Eric A.; Vetter, Russell D.; Warner, Robert R.

    2013-01-01

    Several factors lead to expectations that the scale of larval dispersal and population connectivity of marine animals differs with latitude. We examine this expectation for demersal shorefishes, including relevant mechanisms, assumptions and evidence. We explore latitudinal differences in (i) biological (e.g. species composition, spawning mode, pelagic larval duration, PLD), (ii) physical (e.g. water movement, habitat fragmentation), and (iii) biophysical factors (primarily temperature, which could strongly affect development, swimming ability or feeding). Latitudinal differences exist in taxonomic composition, habitat fragmentation, temperature and larval swimming, and each difference could influence larval dispersal. Nevertheless, clear evidence for latitudinal differences in larval dispersal at the level of broad faunas is lacking. For example, PLD is strongly influenced by taxon, habitat and geographical region, but no independent latitudinal trend is present in published PLD values. Any trends in larval dispersal may be obscured by a lack of appropriate information, or use of ‘off the shelf’ information that is biased with regard to the species assemblages in areas of concern. Biases may also be introduced from latitudinal differences in taxa or spawning modes as well as limited latitudinal sampling. We suggest research to make progress on the question of latitudinal trends in larval dispersal. PMID:23516247

  19. The single event upset environment for avionics at high latitude

    SciTech Connect

    Sims, A.J.; Dyer, C.S.; Peerless, C.L. . Space and Communications Dept.); Johansson, K.; Pettersson, H. ); Farren, J. . Harwell Lab.)

    1994-12-01

    Modern avionic systems for civil and military applications are becoming increasingly reliant upon embedded microprocessors and associated memory devices. The phenomenon of single event upset (SEU) is well known in space systems and designers have generally been careful to use SEU tolerant devices or to implement error detection and correction (EDAC) techniques where appropriate. In the past, avionics designers have had no reason to consider SEU effects but is clear that the more prevalent use of memory devices combined with increasing levels of IC integration will make SEU mitigation an important design consideration for future avionic systems. To this end, it is necessary to work towards producing models of the avionics SEU environment which will permit system designers to choose components and EDAC techniques which are based on predictions of SEU rates correct to much better than an order of magnitude. Measurements of the high latitude SEU environment at avionics altitude have been made on board a commercial airliner. Results are compared with models of primary and secondary cosmic rays and atmospheric neutrons. Ground based SEU tests of static RAMs are used to predict rates in flight.

  20. IRAS galaxies at low galactic and high supergalactic latitudes

    SciTech Connect

    Dow, M.W.; Lu, N.Y.; Houck, J.R.; Salpeter, E.E.; Lewis, B.M.

    1988-01-01

    Based on IR colors, 371 IRAS point sources with absolute value of b = 2-16 deg (b = galactic latitude) were selected for study at H I 21 cm as potential galaxies: 25 percent (93) of these sources are galaxies with redshifts less than 8000 km/s based on H I spectra. Most of the detected galaxies are at redshifts between 2000 and 7500 km/s. Fifty-five of these lie in an area about 40 deg away from the junction of the Pisces-Perseus and Lynx-Ursa Major superclusters, and show a distribution of systemic velocities very similar to these superclusters. There is an enhanced density of galaxies near 6000 km/s with galactic longitude l about 40 deg and b about 0 deg. The two regions surveyed, centered at l about 192 deg and l about 54 deg, lie outside the plane of the Local Supercluster and do not show any preference for galaxies with low velocity widths. 16 references.

  1. IRAS galaxies at low galactic and high supergalactic latitudes

    NASA Technical Reports Server (NTRS)

    Dow, M. W.; Lu, N. Y.; Houck, J. R.; Salpeter, E. E.; Lewis, B. M.

    1988-01-01

    Based on IR colors, 371 IRAS point sources with absolute value of b = 2-16 deg (b = galactic latitude) were selected for study at H I 21 cm as potential galaxies: 25 percent (93) of these sources are galaxies with redshifts less than 8000 km/s based on H I spectra. Most of the detected galaxies are at redshifts between 2000 and 7500 km/s. Fifty-five of these lie in an area about 40 deg away from the junction of the Pisces-Perseus and Lynx-Ursa Major superclusters, and show a distribution of systemic velocities very similar to these superclusters. There is an enhanced density of galaxies near 6000 km/s with galactic longitude l about 40 deg and b about 0 deg. The two regions surveyed, centered at l about 192 deg and l about 54 deg, lie outside the plane of the Local Supercluster and do not show any preference for galaxies with low velocity widths.

  2. DISCOVERY OF AN APPARENT HIGH LATITUDE GALACTIC SUPERNOVA REMNANT

    SciTech Connect

    Fesen, Robert A.; Neustadt, Jack M. M.; Black, Christine S.; Koeppel, Ari H. D.

    2015-10-10

    Deep Hα images of a faint emission complex 4.°0 × 5.°5 in angular extent and located far off the Galactic plane at l = 70.°0, b = −21.°5 reveal numerous thin filaments suggestive of a supernova remnant’s (SNR’s) shock emission. Low dispersion optical spectra covering the wavelength range 4500–7500 Å show only Balmer line emissions for one filament while three others show a Balmer dominated spectrum along with weak [N i] 5198, 5200 Å, [O i] 6300, 6364 Å, [N ii] 6583 Å, [S ii] 6716, 6731 Å, and in one case [O iii] 5007 Å line emission. Many of the brighter Hα filaments are visible in near-UV GALEX images presumably due to C iii] 1909 Å line emission. ROSAT All Sky Survey images of this region show a faint crescent-shaped X-ray emission nebula coincident with the portion of the Hα nebulosity closest to the Galactic plane. The presence of long, thin Balmer dominated emission filaments with associated UV emission and coincident X-ray emission suggests this nebula is a high latitude Galactic SNR despite a lack of known associated nonthermal radio emission. Relative line intensities of the optical lines in some filaments differ from commonly observed [S ii]/Hα ≥ 0.4 radiative shocked filaments and typical Balmer filaments in SNRs. We discuss possible causes for the unusual optical SNR spectra.

  3. Meteorological observations of synoptic disturbances: Sensitivity to latitude

    NASA Technical Reports Server (NTRS)

    Barnes, Jeff R.

    1994-01-01

    The Mars pathfinder MET experiment will make pressure, temperature, and wind measurements on the surface of Mars. The Viking Lander Meteorology Experiment measurements were marked by the presence of variations associated with synoptic weather disturbances throughout the fall and winter season. Numerical simulations of the Mars atmospheric circulation show that the winter midlatitudes are the center of activity for traveling disturbances of planetary scale, disturbances that have their fundamental origin in the baroclinic instability of the wintertime Mars atmospheric circulation. The studies are consistent with Viking observations in that the disturbances decay in amplitude toward lower latitudes. The further north the Mars Pathfinder is located, the more clearly it will be able to detect the signatures of the midlatitude weather system. A landing site close to 15 deg N should allow measurement of the weather disturbances, along with observations of the thermal tides, slope winds, and the relatively steady winds associated with the general circulation - the 'trade winds' of Mars. A landing site near 15 deg N would be significantly further equatorward than the Viking Lander 1 site, and thus would provide more of a view of tropical circulation processes.

  4. An accelerating high-latitude jet in Earth's core

    NASA Astrophysics Data System (ADS)

    Finlay, C. C.; Livermore, P. W.; Hollerbach, R.

    2016-12-01

    The structure of the core-generated magnetic field, and how it changes in time (its secular variation or SV), supplies an invaluable constraint on the dynamics of the outer core. At high latitude, previous studies have noted distinctive behaviour of secular change, in particular suggesting a polar vortex tied to the dynamics within the tangent cylinder region. Recent high-resolution observational models that include data from the Swarm satellites have refined the structure of observed SV, to a rapidly changing circular daisy-chain configuration centred on the north geographic pole, on or very close to the tangent cylinder itself. Motivated by theoretical considerations of the likely dynamical regime of the core, we demonstrate that this feature can be explained by a localised westwards cylindrical jet of 420 km width centred the tangent cylinder, whose amplitude appears to have increased in strength by a factor of three over the period 2000-2016 to about 40 km/yr. The current accelerating phase may be a short fragment of decadal fluctuations of the jet strength linked to both torsional wave activity and the rotation direction of the inner core.

  5. Sun position calculator (SPC) for Landsat imagery with geodetic latitudes

    NASA Astrophysics Data System (ADS)

    Seong, Jeong C.

    2015-12-01

    Landsat imagery comes with sun position information such as azimuth and sun elevation, but they are available only at the center of a scene. To aid in the use of Landsat imagery for various solar radiation applications such as topographic correction, solar power, urban heat island, agriculture, climate and vegetation, it is necessary to calculate the sun position information at every pixel. This research developed a PC application that creates sun position data layers in ArcGIS at every pixel in a Landsat scene. The SPC program is composed of two major routines - converting universal transverse Mercator (UTM) projection coordinates to geographic longitudes and latitudes, and calculating sun position information based on the Meeus' routine. For the latter, an innovative method was also implemented to account for the Earth's flattening on an ellipsoid. The Meeus routine implemented in this research showed about 0.2‧ of mean absolute difference from the National Renewable Energy Laboratory (NREL) Solar Position Algorithm (SPA) routine when solar zenith and azimuth angles were tested with every 30 min data at four city locations (Fairbanks, Atlanta, Sydney and Rio Grande) on June 30, 2014. The Meeus routine was about ten times faster than the SPA routine. Professionals who need the Sun's position information for Landsat imagery will benefit from the SPC application.

  6. Environmental conditions for alternative tree cover states in high latitudes

    NASA Astrophysics Data System (ADS)

    Abis, Beniamino; Brovkin, Victor

    2016-04-01

    Previous analysis of the vegetation cover from remote sensing revealed the existence of three alternative modes in the frequency distribution of boreal tree cover: a sparsely vegetated treeless state, a savanna-like state, and a forest state. Identifying which are the regions subject to multimodality, and assessing which are the main factors underlying their existence, is important to project future change of natural vegetation cover and its effect on climate. We study the impact on the forest cover fraction distribution of seven globally-observed environmental factors: mean annual rainfall, mean minimum temperature, growing degree days above 0, permafrost distribution, soil moisture, wildfire occurrence frequency, and thawing depth. Through the use of generalised additive models, regression trees, and conditional histograms, we find that the main factors determining the forest distribution in high latitudes are: permafrost distribution, mean annual rainfall, mean minimum temperature, soil moisture, and wildfire frequency. Additionally, we find differences between regions within the boreal area, such as Eurasia, Eastern North America, and Western North America. Furthermore, using a classification based on these factors, we show the existence and location of alternative tree cover states under the same climate conditions in the boreal region. These are areas of potential interest for a more detailed analysis of land-atmosphere interactions.

  7. Habitable periglacial landscapes in martian mid-latitudes

    NASA Astrophysics Data System (ADS)

    Ulrich, M.; Wagner, D.; Hauber, E.; de Vera, J.-P.; Schirrmeister, L.

    2012-05-01

    Subsurface permafrost environments on Mars are considered to be zones where extant life could have survived. For the identification of possible habitats it is important to understand periglacial landscape evolution and related subsurface and environmental conditions. Many landforms that are interpreted to be related to ground ice are located in the martian mid-latitudinal belts. This paper summarizes the insights gained from studies of terrestrial analogs to permafrost landforms on Mars. The potential habitability of martian mid-latitude periglacial landscapes is exemplarily deduced for one such landscape, that of Utopia Planitia, by a review and discussion of environmental conditions influencing periglacial landscape evolution. Based on recent calculations of the astronomical forcing of climate changes, specific climate periods are identified within the last 10 Ma when thaw processes and liquid water were probably important for the development of permafrost geomorphology. No periods could be identified within the last 4 Ma which met the suggested threshold criteria for liquid water and habitable conditions. Implications of past and present environmental conditions such as temperature variations, ground-ice conditions, and liquid water activity are discussed with respect to the potential survival of highly-specialized microorganisms known from terrestrial permafrost. We conclude that possible habitable subsurface niches might have been developed in close relation to specific permafrost landform morphology on Mars. These would have probably been dominated by lithoautotrophic microorganisms (i.e. methanogenic archaea).

  8. Ectotherm thermal stress and specialization across altitude and latitude.

    PubMed

    Buckley, Lauren B; Miller, Ethan F; Kingsolver, Joel G

    2013-10-01

    Gradients of air temperature, radiation, and other climatic factors change systematically but differently with altitude and latitude. We explore how these factors combine to produce altitudinal and latitudinal patterns of body temperature, thermal stress, and seasonal overlap that differ markedly from patterns based solely on air temperature. We use biophysical models to estimate body temperature as a function of an organism's phenotype and environmental conditions (air and surface temperatures and radiation). Using grasshoppers as a case study, we compare mean body temperatures and the incidence of thermal extremes along altitudinal gradients both under past and current climates. Organisms at high elevation can experience frequent thermal stress despite generally cooler air temperatures due to high levels of solar radiation. Incidences of thermal stress have increased more rapidly than have increases in mean conditions due to recent climate change. Increases in air temperature have coincided with shifts in cloudiness and solar radiation, which can exacerbate shifts in body temperature. We compare altitudinal thermal gradients and their seasonality between tropical and temperate mountains to ask whether mountain passes pose a greater physiological barrier in the tropics (Janzen's hypothesis). We find that considering body temperature rather than air temperature generally increases the amount of overlap in thermal conditions along gradients in elevation and thus decreases the physiological barrier posed by tropical mountains. Our analysis highlights the limitations of predicting thermal stress based solely on air temperatures, and the importance of considering how phenotypes influence body temperatures.

  9. A polarised fast radio burst at low Galactic latitude

    NASA Astrophysics Data System (ADS)

    Petroff, Emily; SUPERB Collaboration; HESS Collaboration; ANTARES Collaboration

    2017-01-01

    Fast radio bursts (FRBs) are a growing population of transients detected with radio telescopes which are thought to originate outside the Milky Way. Fewer than 20 sources exist in the literature and the majority of bursts have been found away from the plane of the Galaxy or where the Galactic contribution to the total electron column density is low. Here we report on the discovery of a new burst, FRB 150215, discovered with the Parkes radio telescope in real-time in February 2015. The burst was found to be 43±5% linearly polarised with an imprecisely determined rotation measure (RM) consistent with zero. The burst was followed-up with 9 telescopes to search for radio, optical, X-ray, γ-ray and neutrino emission from the location of the burst. No transient or variable emission was found to be associated with the burst and no repeat pulses have been observed in nine hours of Parkes observations. Radio images of the field were obtained following the FRB but would not have been sensitive enough to pick up a signal like the one emanating from WISE J071634.59-190039.2 following FRB150418 if it had been present. The sightline to the burst is close to the Galactic plane and the Galactic RM foreground may approach a null along this sightline, corresponding to a decreased total electron column density from the Milky Way. This might explain why this burst was detectable at low latitude whereas previous searches have been relatively unsuccessful.

  10. Equatorial and Low-Latitudes Ionospheric Reaction to Solar Flares

    NASA Astrophysics Data System (ADS)

    Nicoli Candido, C. M.; Becker-Guedes, F.; Paula, E. R.; Takahashi, H.

    2015-12-01

    Solar X-ray and extreme ultraviolet (EUV) photons are responsible for ionizing the terrestrial atmosphere and create the ionosphere. During solar flares, a fast increase in the electron density at different altitude regions takes place due to the abrupt enhance of the X-ray and EUV fluxes reaching Earth. With these changes in the ionosphere, radio communication and navigation can be drastically affected. The magnitudes of these Space Weather events can be related to the X-ray peak brightness and duration, which drive the intensity of the ionosphere response when the associated electromagnetic wave hit the sunlit side of the Earth's atmosphere. Other aspects defining these changes in a particular region are the local time, the solar zenith angle, and the position of the flare in the solar disc for each event. In order to improve the understand of radio signal degradation and loss in the Brazilian sector due to solar abrupt electromagnetic emissions, total electron content (TEC) data obtained by a GPS network formed by tents of dual-frequency receivers spread all over Brazilian territory were analyzed. It was observed different ionospheric local changes during several X-ray events identified by GOES satellite regarding the 0.1-0.8 nm range, and some case studies were ponder for a more detailed analysis of these effects. Considering the results, we have made an estimation of the ionospheric disturbances range for a particular event with great chance to affect space based communications in the equatorial and low-latitude regions.

  11. Temperature and CO2 emission scenarios from high latitude peatlands

    NASA Astrophysics Data System (ADS)

    Larsen, J.; Hartland, A.; Mariethoz, G.

    2013-12-01

    Soil organic carbon (OC) represents the largest terrestrial carbon store (~twice the mass of atmospheric C), plays a key role in the carbon cycle, and is thought to be susceptible to anthropogenic climate change, yet the sensitivity of this carbon reservoir to potential temperature rises remains poorly quantified. Current estimates are mostly based upon incubation studies in specific locations and for relatively short time periods. Thus, the geographic heterogeneity in soil compositions, microbial plasticity and local climate variation are not always well captured. Thermodynamic theory of soil carbon assimilation suggests that microbial sensitivity to warming is only significant for low quality (i.e. less decomposable) OC, suggesting that changes in OC processing during the warming trend of the last ~40 years will have been facilitated mostly by very low quality carbon. We apply this kinetic theory of OC quality to estimate the likely response of high lattitude peatlands and mires in the Northern Hemipshere to warming scenarios of 0.5-1.5 °C by deriving a joint probability distribution of soil respiration and temperature values from a database of over 100 studies. Our data imply that although a feedback between CO2 efflux from northern peatlands and temperature exists, the potential increases in CO2 efflux from peatlands in high latitude climates due to global warming may have been overstated.

  12. Latitude, elevational climatic zonation and speciation in New World vertebrates.

    PubMed

    Cadena, Carlos Daniel; Kozak, Kenneth H; Gómez, Juan Pablo; Parra, Juan Luis; McCain, Christy M; Bowie, Rauri C K; Carnaval, Ana C; Moritz, Craig; Rahbek, Carsten; Roberts, Trina E; Sanders, Nathan J; Schneider, Christopher J; VanDerWal, Jeremy; Zamudio, Kelly R; Graham, Catherine H

    2012-01-07

    Many biodiversity hotspots are located in montane regions, especially in the tropics. A possible explanation for this pattern is that the narrow thermal tolerances of tropical species and greater climatic stratification of tropical mountains create more opportunities for climate-associated parapatric or allopatric speciation in the tropics relative to the temperate zone. However, it is unclear whether a general relationship exists among latitude, climatic zonation and the ecology of speciation. Recent taxon-specific studies obtained different results regarding the role of climate in speciation in tropical versus temperate areas. Here, we quantify overlap in the climatic distributions of 93 pairs of sister species of mammals, birds, amphibians and reptiles restricted to either the New World tropics or to the Northern temperate zone. We show that elevational ranges of tropical- and temperate-zone species do not differ from one another, yet the temperature range experienced by species in the temperate zone is greater than for those in the tropics. Moreover, tropical sister species tend to exhibit greater similarity in their climatic distributions than temperate sister species. This pattern suggests that evolutionary conservatism in the thermal niches of tropical taxa, coupled with the greater thermal zonation of tropical mountains, may result in increased opportunities for allopatric isolation, speciation and the accumulation of species in tropical montane regions. Our study exemplifies the power of combining phylogenetic and spatial datasets of global climatic variation to explore evolutionary (rather than purely ecological) explanations for the high biodiversity of tropical montane regions.

  13. Latitude, elevational climatic zonation and speciation in New World vertebrates

    PubMed Central

    Cadena, Carlos Daniel; Kozak, Kenneth H.; Gómez, Juan Pablo; Parra, Juan Luis; McCain, Christy M.; Bowie, Rauri C. K.; Carnaval, Ana C.; Moritz, Craig; Rahbek, Carsten; Roberts, Trina E.; Sanders, Nathan J.; Schneider, Christopher J.; VanDerWal, Jeremy; Zamudio, Kelly R.; Graham, Catherine H.

    2012-01-01

    Many biodiversity hotspots are located in montane regions, especially in the tropics. A possible explanation for this pattern is that the narrow thermal tolerances of tropical species and greater climatic stratification of tropical mountains create more opportunities for climate-associated parapatric or allopatric speciation in the tropics relative to the temperate zone. However, it is unclear whether a general relationship exists among latitude, climatic zonation and the ecology of speciation. Recent taxon-specific studies obtained different results regarding the role of climate in speciation in tropical versus temperate areas. Here, we quantify overlap in the climatic distributions of 93 pairs of sister species of mammals, birds, amphibians and reptiles restricted to either the New World tropics or to the Northern temperate zone. We show that elevational ranges of tropical- and temperate-zone species do not differ from one another, yet the temperature range experienced by species in the temperate zone is greater than for those in the tropics. Moreover, tropical sister species tend to exhibit greater similarity in their climatic distributions than temperate sister species. This pattern suggests that evolutionary conservatism in the thermal niches of tropical taxa, coupled with the greater thermal zonation of tropical mountains, may result in increased opportunities for allopatric isolation, speciation and the accumulation of species in tropical montane regions. Our study exemplifies the power of combining phylogenetic and spatial datasets of global climatic variation to explore evolutionary (rather than purely ecological) explanations for the high biodiversity of tropical montane regions. PMID:21632626

  14. Germ Cell Testicular Cancer Incidence, Latitude and Sunlight Associations in the United States and Australia.

    PubMed

    Biggar, Robert J; Baade, Peter D; Sun, Jiandong; Brandon, Lindsay E; Kimlin, Michael

    2016-09-01

    International patterns suggest germ cell testicular cancer (GCTC) incidence may be lower in lower latitudes. To investigate this possibility, we examined GCTC incidence by latitude (population centroid in 2000) for men ≥15 years within two reasonably homogeneous countries, the United States and Australia. In the United States, we examined age-adjusted incidence/latitude trends using data from states (2001-2010) and local-area registries (1980-2011). In Australia, we evaluated incidence/latitude trends in 61 Statistical Divisions (2000-2009). In U.S. White men (68 566 cases), state incidences increased by latitude, rising 5.74% (4.45-7.05%) per 5°North latitude increment. Similar trends were found for seminoma and nonseminoma subtypes (P < 0.001). In U.S. Black men (2256 cases), the association was also seen (4.9%; 0.2-9.7%). In local U.S. data, similar increases in incidence with latitude were present in each of the last three decades. In Australia (6042 cases), the incidence increased by 4.43% (95% CI: 1.54-7.39%) per 5°South, and trends for subtypes were similar. Thus, we found that incidence of GCTC in both White and Black men increased significantly with distance from the equator, approximately 1% per degree within the range of latitudes studied.

  15. Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes

    USGS Publications Warehouse

    McGuire, A.D.; Wirth, C.; Apps, M.; Beringer, J.; Clein, J.; Epstein, H.; Kicklighter, D.W.; Bhatti, J.; Chapin, F. S.; De Groot, B.; Efremov, D.; Eugster, W.; Fukuda, M.; Gower, T.; Hinzman, L.; Huntley, B.; Jia, G.J.; Kasischke, E.; Melillo, J.; Romanovsky, V.; Shvidenko, A.; Vaganov, E.; Walker, D.

    2002-01-01

    The responses of high latitude ecosystems to global change involve complex interactions among environmental variables, vegetation distribution, carbon dynamics, and water and energy exchange. These responses may have important consequences for the earth system. In this study, we evaluated how vegetation distribution, carbon stocks and turnover, and water and energy exchange are related to environmental variation spanned by the network of the IGBP high latitude transects. While the most notable feature of the high latitude transects is that they generally span temperature gradients from southern to northern latitudes, there are substantial differences in temperature among the transects. Also, along each transect temperature co-varies with precipitation and photosynthetically active radiation, which are also variable among the transects. Both climate and disturbance interact to influence latitudinal patterns of vegetation and soil carbon storage among the transects, and vegetation distribution appears to interact with climate to determine exchanges of heat and moisture in high latitudes. Despite limitations imposed by the data we assembled, the analyses in this study have taken an important step toward clarifying the complexity of interactions among environmental variables, vegetation distribution, carbon stocks and turnover, and water and energy exchange in high latitude regions. This study reveals the need to conduct coordinated global change studies in high latitudes to further elucidate how interactions among climate, disturbance, and vegetation distribution influence carbon dynamics and water and energy exchange in high latitudes.

  16. Investigation of High-Latitude Phenomena Using Polar Data and Global Simulations

    NASA Technical Reports Server (NTRS)

    Russell, Christopher T.; Hoffman, Robert (Technical Monitor)

    2001-01-01

    The goal of this one-year project was to use data from the Polar satellite in conjunction with global simulations of Earth's magnetosphere to investigate phenomena in the high-latitude magnetosphere. Specifically, we addressed reconnection at the cusp during periods of northward interplanetary magnetic field (IMF), and the effects of substorms on the high-latitude magnetosphere.

  17. The mid-latitude total ozone trends in the northern hemisphere

    SciTech Connect

    Chandra, S.; Varotsos, C.; Flynn, L.E.

    1996-03-01

    The authors compare trends in column ozone measurements in mid latitudes measured from Nimbus-7 with predictions of 2D photochemical models. They find that the measurements show a larger trended decrease than is predicted by the 2D model. The data shows considerable variability at mid latitudes with longitudinal location.

  18. Vulnerability of high-latitude soil organic carbon in North America to disturbance

    Treesearch

    Guido Grosse; Jennifer Harden; Merritt Turetsky; A. David McGuire; Philip Camill; Charles Tarnocai; Steve Frolking; Edward Schuur; Torre Jorgenson; Sergei Marchenko; Vladimir Romanovsky; Kimberly P. Wickland; Nancy French; Mark Waldrop; Laura Bourgeau-Chavez; Robert G. Streigl

    2011-01-01

    This synthesis addresses the vulnerability of the North American high-latitude soil organic carbon (SOC) pool to climate change. Disturbances caused by climate warming in arctic, subarctic, and boreal environments can result in significant redistribution of C among major reservoirs with potential global impacts. We divide the current northern high-latitude SOC pools...

  19. Occurrence climatology of the electron density irregularities in the mid-latitude E region

    NASA Astrophysics Data System (ADS)

    Kwak, Y.; Yang, T.; Kil, H.

    2013-12-01

    Electron density irregularities in the ionosphere interrupt the propagation of electromagnetic waves and are problematic for navigation and communication systems. For this practical importance, significant efforts have been made to establish information on the occurrence climatology of such irregularities, to understand the onset conditions of such irregularities, and to predict or avoid the impact of these irregularities on the society. While the irregularities occur in all latitudes, less attention has been paid to the irregularities in middle latitudes. This may be because the irregularities in middle latitudes are not as severe as those in other latitude regions. However, middle latitudes are also the place where various forms of irregularities occur. A 40.8 MHz VHF radar was built at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South Korea aiming at continuous monitoring of the behavior of the middle-latitude electron density irregularities in the Far East Asian sector. The radar has been continuously operated by the Korea Astronomy and Space Science Institute (KASI) since December 2009. Using the Daejeon VHF radar data acquired since December 2009, we examine the occurrence types of the irregularities and the dependence of the irregularities on geophysical conditions (local time, altitude, season, solar cycle, and magnetic activity). These results can be used as a tool for investigating the onset conditions of the middle-latitude irregularities.

  20. Ulyssis Observations of Differential Streaming Between Protons and Alphas at High Latitudes

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.; Goldstein, B. E.; Smith, E. J.; Feldman, W. C.

    1995-01-01

    Reported are observations from the Ulysses SWOOPS experiment which provided measurements of the differential streaming between protons and alphas as a function of heliocentric distance and latitude. The data reported are of observations for those periods when Ulysses sampled only the flows from the solar polar coronal holes. All of the high-latitude results differ from the outbound, in-ecliptic data.

  1. Energetic particles and coronal mass ejections in the high latitude heliosphere: Ulysses-LET observations

    SciTech Connect

    Bothmer, V.; Marsden, R. G.; Sanderson, T. R.; Trattner, K. J.; Wenzel, K.-P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.; Uchida, Y.; Hudson, H. S.

    1996-07-20

    We have investigated energetic ions of non-corotating nature in the high latitude heliosphere. Major particle events were observed by Ulysses up to latitudes of 60 deg. S. All were associated with passage of coronal mass ejections (CMEs) over the spacecraft. The relationship of these events with solar activity was investigated using Yohkoh soft X-ray images.

  2. "Michael Jackson World Tour:" Maps and Globes--Latitude and Longitude.

    ERIC Educational Resources Information Center

    Benscoter, Gloria Dee

    1988-01-01

    Presents a mapping activity which helps students understand the purpose of latitude and longitude lines. Gives students an opportunity to use longitude and latitude in a meaningful way by asking them to plan a world concert tour for a rock star. Includes a reproducible activity page. (LS)

  3. "Michael Jackson World Tour:" Maps and Globes--Latitude and Longitude.

    ERIC Educational Resources Information Center

    Benscoter, Gloria Dee

    1988-01-01

    Presents a mapping activity which helps students understand the purpose of latitude and longitude lines. Gives students an opportunity to use longitude and latitude in a meaningful way by asking them to plan a world concert tour for a rock star. Includes a reproducible activity page. (LS)

  4. Coronal mass ejections in the solar wind at high solar latitudes: An overview

    SciTech Connect

    Gosling, J.T.

    1994-10-01

    Ulysses has provided the first direct measurements of coronal mass ejections, CMES, in the solar wind at high heliographic latitudes. This paper provides an overview of new and unexpected results from the plasma experiment on Ulysses, supplemented with magnetic field measurements, during the spacecraft`s first excursion to high solar latitudes. A striking aspect of the high-latitude CMEs observed is that they all had high speeds, with the overall average speed being 730 km s{sup {minus}1}. A new class of forward-reverse shock pairs, associated with expansion of CMES, has been discovered at high latitudes. Of six certain CMEs observed at high latitudes, three have associated shock pairs of this nature. Combined Ulysses and Yohkoh observations suggest that the flux rope topology characteristic of some CMEs results from reconnection within the legs of neighboring magnetic loops embedded within the escaping CMES.

  5. Measurements of free tropospheric ozone - An aircraft survey from 44 degrees north to 46 south latitude

    NASA Technical Reports Server (NTRS)

    Gregory, G. L.; Beck, S. M.; Williams, J. A.

    1984-01-01

    Ozone data were obtained in the free troposphere at altitudes of 5 to 7.5 km and at latitudes from 44 degrees N to 46 degrees S during a 3-week period from October 19 to November 4, 1982. Flight trajectories included the continental U.S., Central America, and the western coast of South America. Maximum observed ozone was 110 ppb at about 41 degrees S latitude and at an altitude of 7.3 km (msl). Analysis of the data as a function of latitude showed a region of elevated ozone in the southern latitudes extending from about 2 degrees to 30 degrees in which latitudinal ozone averages (2 degree bands) peaked at about 80 ppb. Ozone concentrations, measured at northern latitudes, were lower, averaging about 35 ppb. A discussion of the data, including comparison with other ozone data sets, is presented.

  6. Equatorial and low-latitude ionospheric response due to 2009 sudden stratospheric warming, South American sector.

    NASA Astrophysics Data System (ADS)

    Fagundes, Paulo Roberto; Gende, Mauricio; De Jesus, Rodolfo; Goncharenko, Larisa; Coster, Anthea; Kavutarapu, Venkatesh; De Abreu, Alessandro; Pillat, ValdirGil; Pezzopane, Michael

    The equatorial and low-latitude ionosphere/thermosphere system is permanently disturbed by waves (MSTIDs, tides, and planetary waves), which are generated in the lower atmosphere or in situ, as well as electric fields and TIDs produced by geomagnetic storm and UV, EUV, and X-ray solar radiation. Until recently it was thought, that during geomagnetic quiet conditions the equatorial and low-latitude F-layer was mainly perturbed by waves that were generated not far away from the observed location or electric fields generated by electroject. On the contrary during geomagnetic storms when the energy sources are in high latitudes the waves (TIDs) travel a very long distance from high latitude to equatorial region and electric fields can be mapped via magnetic field lines. However, recently an unexpected coupling between high latitude, -mid latitude, and -equatorial/low-latitude was discovered during sudden stratospheric warming (SSW). The exploration of all aspects involved in this process must be investigated in order to improve our knowledge about the Earth's atmosphere. This investigation, studies the consequences of the vertical coupling from lower to upper atmosphere during a major Northern Hemisphere sudden stratospheric warming, which took place in January 2009, on the equatorial and low-latitude ionosphere in the Southern Hemisphere. Using 16 ground-based GPS stations over the Brazilian sector, spanning from latitude 2.8N to 30.1S and longitude 62.0W to 37.7W, it was possible to notice that the ionosphere was disturbed by SSW from the Equator to low latitude. The TEC at all 16 stations was severely disturbed during several days after the SSW temperature peak.

  7. Mid-latitude mesospheric clouds and their environment from SOFIE observations

    NASA Astrophysics Data System (ADS)

    Hervig, Mark E.; Gerding, Michael; Stevens, Michael H.; Stockwell, Robert; Bailey, Scott M.; Russell, James M.; Stober, Gunter

    2016-11-01

    Observations from the Solar Occultation For Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite are used to examine noctilucent clouds (NLC) and their environment at middle latitudes ( 56°N and 52°S). Because SOFIE is uniquely capable of measuring NLC, water vapor, and temperature simultaneously, the local cloud environment can be specified to examine what controls their formation at mid-latitudes. Compared to higher latitudes, mid-latitude NLCs are less frequent and have lower ice mass density, by roughly a factor of five. Compared to higher latitudes at NLC heights, mid-latitude water vapor is only 12% lower while temperatures are more than 10 K higher. As a result the reduced NLC mass and frequency at mid-latitudes can be attributed primarily to temperature. Middle and high latitude NLCs contain a similar amount of meteoric smoke, which was not anticipated because smoke abundance increases towards the equator in summer. SOFIE indicates that mid-latitude NLCs may or may not be associated with supersaturation with respect to ice. It is speculated that this situation is due in part to SOFIE uncertainties related to the limb measurement geometry combined with the non-uniform nature of NLCs. SOFIE is compared with concurrent NLC, temperature, and wind observations from Kühlungsborn, Germany (54°N) during the 2015 summer. The results indicate good agreement in temperature and NLC occurrence frequency, backscatter, and height. SOFIE indicates that NLCs were less frequent over Europe during 2015 compared to other longitudes, in contrast to previous years at higher latitudes that showed no clear longitude dependence. Comparisons of SOFIE and the Solar Backscatter Ultraviolet (SBUV) indicate good agreement in average ice water column (IWC), although differences in occurrence frequency were often large.

  8. Exposed Ice in the Northern Mid-Latitudes of Mars

    NASA Astrophysics Data System (ADS)

    Allen, C. C.

    2007-12-01

    Ice-Rich Layer: Polygonal features with dimensions of approximately 100 meters, bounded by cracks, are commonly observed on the martian northern plains. These features are generally attributed to thermal cracking of ice-rich sediments, in direct analogy to polygons in terrestrial polar regions [1,2]. We mapped polygons in the northern mid-latitudes (30 to 65 N) using MOC and HiRISE images [3]. Polygons are scattered across the northern plains, with a particular concentration in western Utopia Planitia. This region largely overlaps the Late Amazonian Astapus Colles unit, characterized by polygonal terrain and nested pits consistent with periglacial and thermokarst origins [4]. Bright and Dark Polygonal Cracks: An examination of all MOC images (1997 through 2003) covering the study area demonstrated that, at latitudes of 55 to 65 N, most of the imaged polygons show bright bounding cracks. We interpret these bright cracks as exposed ice. Between 40 and 55 N, most of the imaged polygons show dark bounding cracks [5]. These are interpreted as polygons from which the exposed ice has been removed by sublimation. The long-term stability limit for exposed ice, even in deep cracks, apparently lies near 55 N. Bright and Dark Spots: Many HiRISE and MOC frames showing polygons in the northern plains also show small numbers of bright and dark spots, particularly in western Utopia Planitia. Many of the spots are closely associated with collapse features suggestive of thermokarst. The spots range from tens to approximately 100 meters in diameter. The bright spots are interpreted as exposed ice, due to their prevalence on terrain mapped as ice rich. The dark spots are interpreted as former bright spots, which have darkened as the exposed ice is lost by sublimation. The bright spots may be the martian equivalents of pingos, ice-cored mounds found in periglacial regions on Earth [6,7,8,9, 10]. Terrestrial pingos from which the ice core has melted often collapse to form depressions

  9. Modeling of equatorial and low latitude ionosphere over Indian zone

    NASA Astrophysics Data System (ADS)

    Singh Dabas, Raj

    Ionospheric Modeling is important for both scientific and practical purposes. Since the largest variability occurs in the ionospheric F-region and for practical HF communication and other applications it would be suffice to model the changes in the F-region parameters of the ionosphere. Ionospheric Electron Content (IEC) is another parameter useful for the determination of phase path, group delay, dispersion, refraction and Faraday polarization rotation of transionospheric signals. In the present study, two HF prediction models for short and long term and one IEC model are developed for equatorial and low latitude ionosphere. Short term HF prediction model is based on Multiple Regression Analysis (MRA) for the dependence of F- region parameters namely foF2 and M(3000)F2, on solar 2800 MHz flux (F10), and geomagnetic index Ap whereas for long term prediction, Second Degree (SD) coefficients are generated by fitting monthly median foF2 and M(3000)F2 with corresponding 12 monthly mean sunspot numbers (R12) using data over three solar cycles. For MRA, daily foF2, M(3000)F2 values for each hour, obtained from Delhi (28.6N, 77.1E) digital ionosonde for about half a solar cycle are used. MRA coefficients, separately for quiet (Ap¡25) and disturbed (Ap˜25) periods, for foF2 and M(3000)F2, are obtained for every month over 24 UT times using daily F10 and Ap values. Whereas SD coefficients are obtained each month at all local times for all the 14 stations covering a geographic latitude range from about 0 to 45N. Similar to SD model, IEC model is also developed using monthly median foF2 and hmF2 values for each hours for all the 14 stations which are feed into IRI 2000 model to calculate respective IEC values for two altitudes namely 1000km and 2000km. Then second degree coefficients, separately for above two altitudes, are obtained for each month at all local times for all the 14 stations. In this way once appropriate coefficients for each hour for all the twelve months

  10. Hydrated Sulfates in the Southern High Latitudes of Mars

    NASA Astrophysics Data System (ADS)

    Ackiss, S. E.; Wray, J. J.

    2012-12-01

    Sulfates on Mars appear largely concentrated in sedimentary rocks dating to the Late Noachian or Hesperian [e.g., 1], but they are also abundant in Amazonian sand dunes around the north polar cap [2]. The gypsum in those dunes derives from the polar layered deposits [e.g., 3], where it may form when sunlight causes minor melting and weathering of embedded dust. We are investigating whether such processes might have also contributed to sulfate formation elsewhere, specifically in regions surrounding the south polar terrain. Our study regions to date include the Sisyphi Montes (20W-40E and 55-75S) and other mountainous areas near the Thyles Rupes (110-140E and 55-75S), the Ulyxis Rupes (150-180E and 55-70S), and Chamberlin Crater (110-150W and 55-75S). We searched for sulfates using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). TRR3 images were evaluated using standard CRISM procedures, including the "volcano scan" atmospheric correction. We used spectral parameters to identify regions of interest, from which we extracted spectra, which we divided by spectrally neutral regions in the same scene to remove systematic artifacts. The resulting ratio spectra were visually compared to library spectra to identify possible hydrated mineral constituents. Some sulfates in the southern high latitudes appear localized to mountains of the Sisyphi Montes, which have been interpreted as volcanoes that erupted under a Hesperian ice sheet [4]. These sulfates might have formed via volcanic hydrothermal or acid fog alteration. We found that nearly 50% of the images on putative volcanoes in the Sisyphi Montes show a 1.9 μm absorption consistent with hydration. The percentage for images on the plains between volcanoes is actually higher; i.e., hydration is not unique to the volcanoes. Nevertheless, the three locations at which we found the strongest absorptions are all on volcanoes. In the Thyles Rupes region, 25% of the images on putative volcanoes are hydrated with

  11. Impact of interactive radiation on idealized mid-latitude storms

    NASA Astrophysics Data System (ADS)

    Schäfer, Sophia; Voigt, Aiko

    2017-04-01

    The evolution of mid-latitude storms is controlled by the interacting impacts of large-scale advection, vertical motion and diabatic processes. It is widely accepted that understanding and accurately representing the diabatic impact of latent heating is crucial for capturing storm dynamics and their response to climate change. By contrast, little, if any, work has been done to study how radiative heating might impact storms. Here, we address this question by comparing idealized baroclinic lifecycles in the state-of-the-art global atmosphere model ICON in full spherical geometry when radiation is included and when radiative effects are neglected. Following previous work, the level of initial moisture is varied to study possible interactions between latent and radiative impacts. We find that in contrast to latent heating, radiation slows the evolution of the storm and leads to an overall weaker storm. Specifically, including radiation leads to a 10 hPa higher storm central pressure and a 30% to 50% weaker domain-averaged eddy-kinetic energy. The overall weakening impact of radiation is independent of the initial moisture content. However, there is some indication that radiation changes the qualitative evolution of the storm when initial moisture is high. For example, with radiation the low-level eddy-kinetic energy and the storm central pressure are non-monotonic functions in time and show a double peak at day 5 and day 7. This does not occur when radiation is neglected, or when the initial moisture is set to zero. Further simulations will be presented to disentangle the radiative impact of clouds, and to investigate the impact of low-level vs. high-level clouds. Moreover, an analysis of the surface pressure tendency equation will be applied to analyze and compare the impact of adiabatic processes, latent heating and radiative heating. Overall, our results show that radiation, while so far neglected, can play a first-order role for the evolution of individual storms.

  12. Sponge bioerosion accelerated by ocean acidification across species and latitudes?

    NASA Astrophysics Data System (ADS)

    Wisshak, M.; Schönberg, C. H. L.; Form, A.; Freiwald, A.

    2014-06-01

    In many marine biogeographic realms, bioeroding sponges dominate the internal bioerosion of calcareous substrates such as mollusc beds and coral reef framework. They biochemically dissolve part of the carbonate and liberate so-called sponge chips, a process that is expected to be facilitated and accelerated in a more acidic environment inherent to the present global change. The bioerosion capacity of the demosponge Cliona celata Grant, 1826 in subfossil oyster shells was assessed via alkalinity anomaly technique based on 4 days of experimental exposure to three different levels of carbon dioxide partial pressure ( pCO2) at ambient temperature in the cold-temperate waters of Helgoland Island, North Sea. The rate of chemical bioerosion at present-day pCO2 was quantified with 0.08-0.1 kg m-2 year-1. Chemical bioerosion was positively correlated with increasing pCO2, with rates more than doubling at carbon dioxide levels predicted for the end of the twenty-first century, clearly confirming that C. celata bioerosion can be expected to be enhanced with progressing ocean acidification (OA). Together with previously published experimental evidence, the present results suggest that OA accelerates sponge bioerosion (1) across latitudes and biogeographic areas, (2) independent of sponge growth form, and (3) for species with or without photosymbionts alike. A general increase in sponge bioerosion with advancing OA can be expected to have a significant impact on global carbonate (re)cycling and may result in widespread negative effects, e.g. on the stability of wild and farmed shellfish populations, as well as calcareous framework builders in tropical and cold-water coral reef ecosystems.

  13. DHIGLS: DRAO H i Intermediate Galactic Latitude Survey

    NASA Astrophysics Data System (ADS)

    Blagrave, K.; Martin, P. G.; Joncas, G.; Kothes, R.; Stil, J. M.; Miville-Deschênes, M. A.; Lockman, Felix J.; Taylor, A. R.

    2017-01-01

    Observations of Galactic H i gas for seven targeted regions at intermediate Galactic latitude are presented at 1\\prime angular resolution using data from the DRAO Synthesis Telescope (ST) and the Green Bank Telescope (GBT). The DHIGLS data are the most extensive arcminute-resolution measurements of the diffuse atomic interstellar medium beyond those in the Galactic plane. The acquisition, reduction, calibration, and mosaicking of the DRAO ST data and the cross calibration and incorporation of the short-spacing information from the GBT are described. The high quality of the resulting DHIGLS products enables a variety of new studies in directions of low Galactic column density. We analyze the angular power spectra of maps of the integrated H i emission (column density) from the data cubes for several distinct velocity ranges. In fitting power-spectrum models based on a power law, but including the effects of the synthesized beam and noise at high spatial frequencies, we find exponents ranging from -2.5 to -3.0. Power spectra of maps of the centroid velocity for these components give similar results. These exponents are interpreted as being representative of the three-dimensional density and velocity fields of the atomic gas, respectively. We find evidence for dramatic changes in the H i structures in channel maps over even small changes in velocity. This narrow line emission has counterparts in absorption spectra against bright background radio sources, quantifying that the gas is cold and dense and can be identified as the cold neutral medium phase. Fully reduced DHIGLS H i data cubes and other data products are available at www.cita.utoronto.ca/DHIGLS.

  14. Ionosphere-Thermosphere Coupling in Jupiter's Low Latitudes

    NASA Astrophysics Data System (ADS)

    Stallard, T.; Melin, H.; Johnson, R.; O'Donoghue, J.; Moore, L.; Miller, S.; Tao, C.; Achilleos, N. A.; Smith, C.; Ray, L. C.; Yates, J. N.

    2015-12-01

    One of the leading problems in our understanding of Jupiter's atmosphere, known colloquially as the 'energy crisis', is that the upper atmosphere has global temperatures far in excess of that predicted by solar heating. Unlike the Earth, solar heating has only a small effect on the thermosphere, varying little in temperature with local time, and with equatorial neutrals co-rotating with the planet due to meridional advection. Within the auroral region, ionosphere-thermosphere coupling produces strong flows and results in huge Joule Heating from auroral currents. In this region, the temperature excess can be explained, but Jupiter's fast rotation means that Coriolis forces prevent energy in the poles from transferring equatorward, so there remains no explanation of why low latitudes are overheated by a factor of 3-5 over that predicted by solar heating alone.Despite this anomaly, although the past twenty years has seen a wealth of new data and results in Jupiter's auroral region, studies of the equatorial region have been somewhat limited. This lack of investigation comes partly from the apparent uniform nature of the equatorial region, and partly from the difficulty in observing this region. It is only in the past three years that observers begun to re-examine this region, revealing evidence of complex interactions between the thermosphere and ionosphere, including what appears to be thermospheric weather patterns at a fixed planetary longitudes, stable over two decades; perhaps caused by continuous flows from the auroral region. Here, we introduce our recent research, in order to compare and contrast what has been observed at Jupiter with the more well understood interactions between Earth's ionosphere and thermosphere. We hope that this will open a discussion between the communities that will improve our understanding of the underlying physical processes, as they occur at both planets.

  15. Longitudinal Variability of the Low Latitude Ionosphere and Scintillation Activity

    NASA Astrophysics Data System (ADS)

    Anderson, D. N.; Fedrizzi, M.; Coker, C.; Dymond, K.; Budzien, S.; Chua, D.; Basu, S.; Caton, R.

    2007-12-01

    Longitudinal variability of the post-sunset low latitude ionosphere is provided by Tiny Ionospheric Photometers (TIP) on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. The TIP sensor is a compact, nadir directed, narrow-band, ultraviolet photometer operating at the 135.6 nm wavelength. This emission is produced by radiative recombination of O+ ions and electrons. At night, the strength of the emission is proportional to the square of the peak electron density, Nmax. TIP measures the horizontal structure of the ionosphere with 15-30 km resolution and high sensitivity, providing detailed observations of the post-sunset equatorial anomaly even during solar minimum conditions. It has previously been demonstrated by Whalen, that the maximum value of the pre-reversal enhancement in vertical ExB drift is linearly related to the value of Nmax at the crest of the equatorial anomaly at 2000 LT. A linear relationship has also been established between the TIP 135.6 nm radiances at the crest of the equatorial anomaly at 2000 LT and the pre-reversal enhancement in vertical ExB drift velocities at 1900 LT in the Peruvian longitude sector. This relationship is independent of the magnitude of the daytime vertical ExB drift velocities. Based on this relationship and TIP 135.6 nm observations, a longitude variation in the pre-reversal enhancement in ExB drift reveals a 4-cell pattern that is attributed to non-migrating tides which arise from tropospheric weather patterns in the tropics. The longitudinal pattern of the pre-reversal enhancement suggests that certain longitudes are more favored than others for the subsequent development of scintillation activity. The strength of this relationship is investigated using scintillation observations from the SCINDA network of ground-based VHF and UHF receivers. A strong relationship implies a connection between tropospheric weather and the occurrence of scintillation activity.

  16. Assessing mid-latitude dynamics in extreme event attribution systems

    NASA Astrophysics Data System (ADS)

    Mitchell, Daniel; Davini, Paolo; Harvey, Ben; Massey, Neil; Haustein, Karsten; Woollings, Tim; Jones, Richard; Otto, Fredi; Guillod, Benoit; Sparrow, Sarah; Wallom, David; Allen, Myles

    2017-06-01

    Atmospheric modes of variability relevant for extreme temperature and precipitation events are evaluated in models currently being used for extreme event attribution. A 100 member initial condition ensemble of the global circulation model HadAM3P is compared with both the multi-model ensemble from the Coupled Model Inter-comparison Project, Phase 5 (CMIP5) and the CMIP5 atmosphere-only counterparts (AMIP5). The use of HadAM3P allows for huge ensembles to be computed relatively fast, thereby providing unique insights into the dynamics of extremes. The analysis focuses on mid Northern Latitudes (primarily Europe) during winter, and is compared with ERA-Interim reanalysis. The tri-modal Atlantic eddy-driven jet distribution is remarkably well captured in HadAM3P, but not so in the CMIP5 or AMIP5 multi-model mean, although individual models fare better. The well known underestimation of blocking in the Atlantic region is apparent in CMIP5 and AMIP5, and also, to a lesser extent, in HadAM3P. Pacific blocking features are well produced in all modeling initiatives. Blocking duration is biased towards models reproducing too many short-lived events in all three modelling systems. Associated storm tracks are too zonal over the Atlantic in the CMIP5 and AMIP5 ensembles, but better simulated in HadAM3P with the exception of being too weak over Western Europe. In all cases, the CMIP5 and AMIP5 performances were almost identical, suggesting that the biases in atmospheric modes considered here are not strongly coupled to SSTs, and perhaps other model characteristics such as resolution are more important. For event attribution studies, it is recommended that rather than taking statistics over the entire CMIP5 or AMIP5 available models, only models capable of producing the relevant dynamical phenomena be employed.

  17. Two dimensional hydrodynamic modeling of a high latitude braided river

    NASA Astrophysics Data System (ADS)

    Humphries, E.; Pavelsky, T.; Bates, P. D.

    2014-12-01

    Rivers are a fundamental resource to physical, ecologic and human systems, yet quantification of river flow in high-latitude environments remains limited due to the prevalence of complex morphologies, remote locations and sparse in situ monitoring equipment. Advances in hydrodynamic modeling and remote sensing technology allow us to address questions such as: How well can two-dimensional models simulate a flood wave in a highly 3-dimensional braided river environment, and how does the structure of such a flood wave differ from flow down a similar-sized single-channel river? Here, we use the raster-based hydrodynamic model LISFLOOD-FP to simulate flood waves, discharge, water surface height, and velocity measurements over a ~70 km reach of the Tanana River in Alaska. In order to use LISFLOOD-FP a digital elevation model (DEM) fused with detailed bathymetric data is required. During summer 2013, we surveyed 220,000 bathymetric points along the study reach using an echo sounder system connected to a high-precision GPS unit. The measurements are interpolated to a smooth bathymetric surface, using Topo to Raster interpolation, and combined with an existing five meter DEM (Alaska IfSAR) to create a seamless river terrain model. Flood waves are simulated using varying complexities in model solvers, then compared to gauge records and water logger data to assess major sources of model uncertainty. Velocity and flow direction maps are also assessed and quantified for detailed analysis of braided channel flow. The most accurate model output occurs with using the full two-dimensional model structure, and major inaccuracies appear to be related to DEM quality and roughness values. Future work will intercompare model outputs with extensive ground measurements and new data from AirSWOT, an airborne analog for the Surface Water and Ocean Topography (SWOT) mission, which aims to provide high-resolution measurements of terrestrial and ocean water surface elevations globally.

  18. Study of the low latitude ionospheric turbulence observed by DEMETER

    NASA Astrophysics Data System (ADS)

    Li, F.; Lefeuvre, F.; Parrot, M.

    Following previous works from Molchanov et al 2002a 2002b 2004a 2004b and Hobara et al 2005 data bases dedicated to the systematic analysis of the power and spectral indices of the electric field have been elaborated Two data bases are considered one for the survey mode and the other for the burst mode For the survey mode estimations of the turbulence parameters are performed from the 8 first Fourier components of the averaged power spectra 0-150 Hz frequency band A single slope power law model f - alpha is assumed A quality factor allows to test that hypothesis For the burst mode the power spectra are derived from the waveforms One and two slope models are systematically tested Results are presented and the possibility to use these data bases for correlation with seismic activity is discussed Y Hobara F Lefeuvre M Parrot and O A Molchanov Low-latitude ionospheric turbulence observed by Aureol-3 satellite Annales Geophysicae 23 1259--1270 2005 Molchanov O A Hayakawa M Afonin V V Akentieva O A and Mareev E A Possible influence of seismicity by gravity waves on ionospheric equatorial anomaly from data of IK-24 satellite 1 Search for idea of seismo-ionosphere coupling Seismo Electromagnetics Lithosphere-Atmosphere-Ionosphere Coupling edited by Hayakawa M and Molchanov O A TERRAPUB Tokyo 275--285 2002a Molchanov O A Hayakawa M Afonin V V Akentieva O A Mareev E A and Trakhtengerts V Yu Possible influence of seismicity by gravity waves on ionospheric

  19. Mid-Latitude Circulation and Extremes in a Changing Climate

    SciTech Connect

    Chen, Gang

    2016-08-04

    Mid-latitude extreme weather events are responsible for a large part of climate-related damage. Yet large uncertainties remain in climate model projections of heat waves, droughts, and heavy rain/snow events on regional scales, limiting our ability to effectively use these projections for climate adaptation and mitigation. These uncertainties can be attributed to both the lack of spatial resolution in the models, and to the lack of a dynamical understanding of these extremes. The approach of this project is to relate the fine-scale features to the large scales in current climate simulations, seasonal re-forecasts, and climate change projections in a very wide range of models, including the atmospheric and coupled models of ECMWF over a range of horizontal resolutions (125 to 10 km), aqua-planet configuration of the Model for Prediction Across Scales and High Order Method Modeling Environments (resolutions ranging from 240 km – 7.5 km) with various physics suites, and selected CMIP5 model simulations. The large scale circulation will be quantified both on the basis of the well tested preferred circulation regime approach, and very recently developed measures, the finite amplitude Wave Activity (FAWA) and its spectrum. The fine scale structures related to extremes will be diagnosed following the latest approaches in the literature. The goal is to use the large scale measures as indicators of the probability of occurrence of the finer scale structures, and hence extreme events. These indicators will then be applied to the CMIP5 models and time-slice projections of a future climate.

  20. Under-Ice Operations with AUVS in High Latitudes

    NASA Astrophysics Data System (ADS)

    Ferguson, J.; Kaminski, C. D.

    2012-12-01

    In 2010 and 2011, ISE Explorer Autonomous Underwater Vehicles (AUV), built for Natural Resources Canada (NRCan), were deployed to Canada's high Arctic. The mission was to undertake under-ice bathymetric surveys supporting Canada's submission under the United Nations Convention on the Law of the Sea (UNCLOS). During these deployments several under-ice records were broken and several new technologies were demonstrated. The NRCan AUV is a 5000 meter depth rated vehicle, with several innovative additions to make it suitable for arctic survey work. Most notable are a depth rated variable ballast system, a 1300 Hz long-range homing system, and under-ice charging and data transfer capabilities. The Explorer's range was extended to approximately 450 km by adding a hull section to accommodate extra batteries. The scientific payload onboard included a Seabird SBE49 Conductivity-Temperature-Depth (CTD) sensor, Knudsen singlebeam echosounder, and a Kongsberg Simrad EM2000 multibeam echosounder. In 2010, operations were conducted from an ice camp near Borden Island (78°14'N, 112°39'W) operating through an ice hole. Following several test missions, the AUV spent 10 days surveying under ice before being successfully recovered. In total, close to 1100 km of under-ice survey was undertaken at depths to 3160 meters. A further set of operations was carried out in August and September 2011 from the Canadian Icebreaker CCGS Louis St. Laurent operating with the American Icebreaker USCGS Healy. Here the operations were much further north to latitudes of 88°30' N and to depths of 3500 meters. In this paper, the 2010 ice camp and the 2011 icebreaker missions are described, with an outline of technology developments that were undertaken, the preparations that were necessary for the success of the missions and finally, the outcome of the missions themselves.

  1. HIGH ECLIPTIC LATITUDE SURVEY FOR SMALL MAIN-BELT ASTEROIDS

    SciTech Connect

    Terai, Tsuyoshi; Takahashi, Jun; Itoh, Yoichi

    2013-11-01

    Main-belt asteroids have been continuously colliding with one another since they were formed. Their size distribution is primarily determined by the size dependence of asteroid strength against catastrophic impacts. The strength scaling law as a function of body size could depend on collision velocity, but the relationship remains unknown, especially under hypervelocity collisions comparable to 10 km s{sup –1}. We present a wide-field imaging survey at an ecliptic latitude of about 25° for investigating the size distribution of small main-belt asteroids that have highly inclined orbits. The analysis technique allowing for efficient asteroid detections and high-accuracy photometric measurements provides sufficient sample data to estimate the size distribution of sub-kilometer asteroids with inclinations larger than 14°. The best-fit power-law slopes of the cumulative size distribution are 1.25 ± 0.03 in the diameter range of 0.6-1.0 km and 1.84 ± 0.27 in 1.0-3.0 km. We provide a simple size distribution model that takes into consideration the oscillations of the power-law slope due to the transition from the gravity-scaled regime to the strength-scaled regime. We find that the high-inclination population has a shallow slope of the primary components of the size distribution compared to the low-inclination populations. The asteroid population exposed to hypervelocity impacts undergoes collisional processes where large bodies have a higher disruptive strength and longer lifespan relative to tiny bodies than the ecliptic asteroids.

  2. Kinematics and chemistry of faint high latitude dwarf carbon stars

    NASA Astrophysics Data System (ADS)

    Yoon, Jinmi; Beers, Timothy C.; Dietz, Sarah; Lee, Young Sun; Placco, Vinicius M.

    2017-01-01

    The diffuse halo system of the Milky Way is complex, and has been shown to comprise at least two main components: a near-zero net rotation inner-halo and a more rapidly rotating outer-halo component. Studies of the ancient, very metal-poor stars in the Galactic halo system are crucial for understanding its early formation history. The so-called carbon-enhanced metal-poor (CEMP) stars are an important subset of the stars in the halo system, which exhibit distinctive kinematic and chemical signatures that can be used to constrain the star-formation histories and assembly of the various Galactic components.We have examined the sample of main-sequence dwarf and other faint high Galactic latitude carbon-enhanced stars from the Sloan Digital Sky Survey studied by Green (2013). As noted by Green, many of these starsexhibit high proper motions, which have been later claimed to be related to possible binary ejection models Plant et al. (2016). By use of the CEMP sub-classification approach of Yoon et al. (2016), we investigate whether the kinematics of these stars might instead result from their membership in the inner/outer halo populations of the Galaxy.ReferencesGreen, P. 2013, ApJ, 765, 12Plant, K. et al. 2016, AAS 227.34115Yoon, J. et al. 2016, ApJ, in pressAcknowledgementThis work was supported in part by the National Science Foundation under Grant No. PHY-1430152 (JINA Center for the Evolution of the Elements).

  3. High northern latitude temperature extremes, 1400-1999

    NASA Astrophysics Data System (ADS)

    Tingley, M. P.; Huybers, P.; Hughen, K. A.

    2009-12-01

    There is often an interest in determining which interval features the most extreme value of a reconstructed climate field, such as the warmest year or decade in a temperature reconstruction. Previous approaches to this type of question have not fully accounted for the spatial and temporal covariance in the climate field when assessing the significance of extreme values. Here we present results from applying BARSAT, a new, Bayesian approach to reconstructing climate fields, to a 600 year multiproxy temperature data set that covers land areas between 45N and 85N. The end result of the analysis is an ensemble of spatially and temporally complete realizations of the temperature field, each of which is consistent with the observations and the estimated values of the parameters that define the assumed spatial and temporal covariance functions. In terms of the spatial average temperature, 1990-1999 was the warmest decade in the 1400-1999 interval in each of 2000 ensemble members, while 1995 was the warmest year in 98% of the ensemble members. A similar analysis at each node of a regular 5 degree grid gives insight into the spatial distribution of warm temperatures, and reveals that 1995 was anomalously warm in Eurasia, whereas 1998 featured extreme warmth in North America. In 70% of the ensemble members, 1601 featured the coldest spatial average, indicating that the eruption of Huaynaputina in Peru in 1600 (with a volcanic explosivity index of 6) had a major cooling impact on the high northern latitudes. Repeating this analysis at each node reveals the varying impacts of major volcanic eruptions on the distribution of extreme cooling. Finally, we use the ensemble to investigate extremes in the time evolution of centennial temperature trends, and find that in more than half the ensemble members, the greatest rate of change in the spatial mean time series was a cooling centered at 1600. The largest rate of centennial scale warming, however, occurred in the 20th Century in

  4. Statistical Characterization of Stormtime Ionospheric Redistribution At Mid-Latitudes

    NASA Astrophysics Data System (ADS)

    Erickson, P. J.; Foster, J. C.; Miskin, M. Z.; Beroz, F.; Rideout, W.

    2009-12-01

    During major geomagnetic disturbances, dramatic redistribution of ionospheric plasma can occur in the mid-latitude plasmasphere boundary layer, driven by a complex set of interlocked dynamics involving photoionization, magnetospheric influence, ionospheric feedback mechanisms, and the background magnetic field direction. Large amounts of ionospheric material are seen to stream from the dusk sector sunward to the polar cap cusp region, as mesoscale plumes of storm enhanced density (SED) move under the influence of the sub-auroral polarization stream (SAPS) electric field in regions magnetically linked to the region 2 currents associated with the asymmetric ring current. Studies over the last decade have shown that these several degree wide SAPS flow channels, with sunward fluxes delivering over 1E14 ions/m^2/sec to the noontime cusp, are the signatures of processes which can deplete an entire L shell of plasmaspheric material in one hours' time for particularly intense storms. Ground based ionospheric radar measurements of these features lend considerable insight into magnetosphere-ionosphere coupling processes and dynamics. We discuss a statistical study of SAPS/SED region sunward ionospheric flux in the dusk magnetic local time sector using a database of over 1000 Millstone Hill ionospheric radar scans during Kp >= 3 disturbances from 1979-2001. We highlight several persistent features of ionospheric F region velocity and SAPS ion flux magnitude. In particular, sunward F region ion flux is relatively insensitive to magnetic local time and the passage of the dusk solar terminator. Potential explanations focus on the interplay between poleward perpendicular electric field and ionospheric height-integrated Pedersen conductance in the E and F regions as the thermosphere and ionosphere change state from day to night.

  5. EDITORIAL: Northern Hemisphere high latitude climate and environmental change

    NASA Astrophysics Data System (ADS)

    Groisman, Pavel; Soja, Amber

    2007-10-01

    High Northern Hemisphere latitudes are undergoing rapid and significant change associated with climate warming. Climatic change in this region interacts with and affects the rate of the global change through atmospheric circulation, biogeophysical, and biogeochemical feedbacks. Changes in the surface energy balance, hydrologic cycle, and carbon budget feedback to regional and global weather and climate systems. Two-thirds of the Northern Hemisphere high latitude land mass resides in Northern Eurasia (~20% of the global land mass), and this region has undergone sweeping socio-economic change throughout the 20th century. How this carbon-rich, cold region component of the Earth system functions as a regional entity and interacts with and feeds back to the greater global system is to a large extent unknown. To mitigate the deficiencies in understanding these feedbacks, which may in turn hamper our understanding of the global change rates and patterns, an initiative was formed. Three years ago the Northern Eurasia Earth Science Partnership Initiative (NEESPI) was established to address large-scale and long-term manifestations of climate and environmental change in this region. The NEESPI Science Plan and its Executive Summary have been published at the NEESPI web site (neespi.org). Since 2004, NEESPI participants have been able to seed several waves of research proposals to international and national funding agencies and institutions and also contribute to the International Polar Year. Currently, NEESPI is widely recognized and endorsed by several Earth System Science Partnership (ESSP) programmes and projects: the International Geosphere and Biosphere Programme, the World Climate Research Programme through the Global Energy and Water Cycle Experiment and Climate and Cryosphere Projects, the Global Water System Project, Global Carbon Project, Global Land Project, and the Integrated Land Ecosystem—Atmosphere Processes Study. Through NEESPI, more than 100 individually

  6. Comparative sequence stratigraphy of low-latitude versus high-latitude lacustrine rift basins: Seismic data examples from the East African and Baikal rifts

    USGS Publications Warehouse

    Scholz, C.A.; Moore, T.C.; Hutchinson, D.R.; Golmshtok, A. Ja; Klitgord, Kim D.; Kurotchkin, A.G.

    1998-01-01

    Lakes Baikal, Malawi and Tanganyika are the world's three largest rift valley lakes and are the classic modem examples of lacustrine rift basins. All the rift lakes are segmented into half-graben basins, and seismic reflection datasets reveal how this segmentation controls the filling of the rift basins through time. In the early stages of rifting, basins are fed primarily by flexural margin and axial margin drainage systems. At the climax of syn-rift sedimentation, however, when the basins are deeply subsided, almost all the margins are walled off by rift shoulder uplifts, and sediment flux into the basins is concentrated at accommodation zone and axial margin river deltas. Flexural margin unconformities are commonplace in the tropical lakes but less so in high-latitude Lake Baikal. Lake levels are extremely dynamic in the tropical lakes and in low-latitude systems in general because of the predominance of evaporation in the hydrologic cycle in those systems. Evaporation is minimized in relation to inflow in the high-latitude Lake Baikal and in most high-latitude systems, and consequently, major sequence boundaries tend to be tectonically controlled in that type of system. The acoustic stratigraphies of the tropical lakes are dominated by high-frequency and high-amplitude lake level shifts, whereas in high-latitude Lake Baikal, stratigraphic cycles are dominated by tectonism and sediment-supply variations.

  7. Extrapair paternity rates vary with latitude and elevation in emberizid sparrows.

    PubMed

    Bonier, Frances; Eikenaar, Cas; Martin, Paul R; Moore, Ignacio T

    2014-01-01

    Mating systems can vary among species and populations and thus influence evolutionary trajectories, ecological traits, and population demography. The siring of offspring by an extrapair male, or extrapair paternity (EPP), is a widespread and varied phenomenon in all vertebrate classes. However, we do not understand all of the factors associated with variation in EPP rates. The breeding synchrony hypothesis suggests that EPP rates should increase with latitude and elevation, whereas the paternal care hypothesis predicts that EPP rates should decrease with elevation. To address these hypotheses, we investigated how population EPP rates vary over elevation and latitude in emberizid sparrows. In comparative analyses including the effects of phylogeny, the relationship between EPP rates and elevation depended on latitude. EPP rates were greater in higher-latitude populations. But within higher-latitude populations, EPP rates decreased with increasing elevation. These findings provide support for both the breeding synchrony and paternal care hypotheses, suggesting that in lower-latitude, higher-elevation populations, the need for male parental care does not outweigh the benefits of seeking extrapair fertilizations in populations with relatively synchronous breeding. In contrast, at higher-latitude, higher-elevation sites, the need for male parental care is greater and might drive lower rates of extrapair mating despite highly synchronous breeding.

  8. Is There a Relationship between Fish Cannibalism and Latitude or Species Richness?

    PubMed

    Pereira, Larissa Strictar; Keppeler, Friedrich Wolfgang; Agostinho, Angelo Antonio; Winemiller, Kirk O

    2017-01-01

    Cannibalism has been commonly observed in fish from northern and alpine regions and less frequently reported for subtropical and tropical fish in more diverse communities. Assuming all else being equal, cannibalism should be more common in communities with lower species richness because the probability of encountering conspecific versus heterospecific prey would be higher. A global dataset was compiled to determine if cannibalism occurrence is associated with species richness and latitude. Cannibalism occurrence, local species richness and latitude were recorded for 4,100 populations of 2,314 teleost fish species. Relationships between cannibalism, species richness and latitude were evaluated using generalized linear mixed models. Species richness was an important predictor of cannibalism, with occurrences more frequently reported for assemblages containing fewer species. Cannibalism was positively related with latitude for both marine and freshwater ecosystems in the Northern Hemisphere, but not in the Southern Hemisphere. The regression slope for the relationship was steeper for freshwater than marine fishes. In general, cannibalism is more frequent in communities with lower species richness, and the relationship between cannibalism and latitude is stronger in the Northern Hemisphere. In the Southern Hemisphere, weaker latitudinal gradients of fish species richness may account for the weak relationship between cannibalism and latitude. Cannibalism may be more common in freshwater than marine systems because freshwater habitats tend to be smaller and more closed to dispersal. Cannibalism should have greatest potential to influence fish population dynamics in freshwater systems at high northern latitudes.

  9. Does greater thermal plasticity facilitate range expansion of an invasive terrestrial anuran into higher latitudes?

    PubMed

    Winwood-Smith, Hugh S; Alton, Lesley A; Franklin, Craig E; White, Craig R

    2015-01-01

    Temperature has pervasive effects on physiological processes and is critical in setting species distribution limits. Since invading Australia, cane toads have spread rapidly across low latitudes, but slowly into higher latitudes. Low temperature is the likely factor limiting high-latitude advancement. Several previous attempts have been made to predict future cane toad distributions in Australia, but understanding the potential contribution of phenotypic plasticity and adaptation to future range expansion remains challenging. Previous research demonstrates the considerable thermal metabolic plasticity of the cane toad, but suggests limited thermal plasticity of locomotor performance. Additionally, the oxygen-limited thermal tolerance hypothesis predicts that reduced aerobic scope sets thermal limits for ectotherm performance. Metabolic plasticity, locomotor performance and aerobic scope are therefore predicted targets of natural selection as cane toads invade colder regions. We measured these traits at temperatures of 10, 15, 22.5 and 30°C in low- and high-latitude toads acclimated to 15 and 30°C, to test the hypothesis that cane toads have adapted to cooler temperatures. High-latitude toads show increased metabolic plasticity and higher resting metabolic rates at lower temperatures. Burst locomotor performance was worse for high-latitude toads. Other traits showed no regional differences. We conclude that increased metabolic plasticity may facilitate invasion into higher latitudes by maintaining critical physiological functions at lower temperatures.

  10. A comparison of hip fracture incidence rates among elderly in Sweden by latitude and sunlight exposure.

    PubMed

    Nilson, Finn; Moniruzzaman, Syed; Andersson, Ragnar

    2014-03-01

    Research has shown that hip fracture risk increases with latitude; hypothetically due to reduced sunlight exposure and its effect on bone quality. Sweden, with large differences in latitude and UV radiation, is ideal to study in order to analyse the association between latitude and UV radiation on age- and sex-specific hip fracture rates among elderly. Aggregated (2006-2008) age- and sex-specific hip fracture data was obtained for each Swedish municipality as well as the municipality's latitudinal coordinates and aggregated (2006-2008) UV radiation levels. Pearson correlations were calculated between hip fracture incidence rates, latitude and UV radiation. Independent t tests were calculated on tertile-categorized latitudinal data in order to investigate the difference in hip fracture risk between these categories. Statistically significant correlations were seen in all groups between hip fracture incidence rates and latitude as well as UV radiation. The independent t tests showed that this correlation was mainly due to high incidence rates in high latitude municipalities. Statistically significant correlations are seen between hip fracture incidence rates and latitude as well as UV radiation in Sweden and the northern parts of Sweden have an increased risk of hip fractures compared to the middle and southern parts. To our knowledge this is the first study using a national discharge register that shows this relationship and provides a starting point for further research to investigate why populations in northern Sweden have a higher risk of hip fractures compared to other Swedish regions.

  11. Nitrogen-fixing tree abundance in higher-latitude North America is not constrained by diversity.

    PubMed

    Menge, Duncan N L; Batterman, Sarah A; Liao, Wenying; Taylor, Benton N; Lichstein, Jeremy W; Ángeles-Pérez, Gregorio

    2017-07-01

    The rarity of nitrogen (N)-fixing trees in frequently N-limited higher-latitude (here, > 35°) forests is a central biogeochemical paradox. One hypothesis for their rarity is that evolutionary constraints limit N-fixing tree diversity, preventing N-fixing species from filling available niches in higher-latitude forests. Here, we test this hypothesis using data from the USA and Mexico. N-fixing trees comprise only a slightly smaller fraction of taxa at higher vs. lower latitudes (8% vs. 11% of genera), despite 11-fold lower abundance (1.2% vs. 12.7% of basal area). Furthermore, N-fixing trees are abundant but belong to few species on tropical islands, suggesting that low absolute diversity does not limit their abundance. Rhizobial taxa dominate N-fixing tree richness at lower latitudes, whereas actinorhizal species do at higher latitudes. Our results suggest that low diversity does not explain N-fixing trees' rarity in higher-latitude forests. Therefore, N limitation in higher-latitude forests likely results from ecological constraints on N fixation. © 2017 John Wiley & Sons Ltd/CNRS.

  12. Is There a Relationship between Fish Cannibalism and Latitude or Species Richness?

    PubMed Central

    Keppeler, Friedrich Wolfgang; Agostinho, Angelo Antonio; Winemiller, Kirk O.

    2017-01-01

    Cannibalism has been commonly observed in fish from northern and alpine regions and less frequently reported for subtropical and tropical fish in more diverse communities. Assuming all else being equal, cannibalism should be more common in communities with lower species richness because the probability of encountering conspecific versus heterospecific prey would be higher. A global dataset was compiled to determine if cannibalism occurrence is associated with species richness and latitude. Cannibalism occurrence, local species richness and latitude were recorded for 4,100 populations of 2,314 teleost fish species. Relationships between cannibalism, species richness and latitude were evaluated using generalized linear mixed models. Species richness was an important predictor of cannibalism, with occurrences more frequently reported for assemblages containing fewer species. Cannibalism was positively related with latitude for both marine and freshwater ecosystems in the Northern Hemisphere, but not in the Southern Hemisphere. The regression slope for the relationship was steeper for freshwater than marine fishes. In general, cannibalism is more frequent in communities with lower species richness, and the relationship between cannibalism and latitude is stronger in the Northern Hemisphere. In the Southern Hemisphere, weaker latitudinal gradients of fish species richness may account for the weak relationship between cannibalism and latitude. Cannibalism may be more common in freshwater than marine systems because freshwater habitats tend to be smaller and more closed to dispersal. Cannibalism should have greatest potential to influence fish population dynamics in freshwater systems at high northern latitudes. PMID:28122040

  13. Does greater thermal plasticity facilitate range expansion of an invasive terrestrial anuran into higher latitudes?

    PubMed Central

    Winwood-Smith, Hugh S.; Alton, Lesley A.; Franklin, Craig E.; White, Craig R.

    2015-01-01

    Temperature has pervasive effects on physiological processes and is critical in setting species distribution limits. Since invading Australia, cane toads have spread rapidly across low latitudes, but slowly into higher latitudes. Low temperature is the likely factor limiting high-latitude advancement. Several previous attempts have been made to predict future cane toad distributions in Australia, but understanding the potential contribution of phenotypic plasticity and adaptation to future range expansion remains challenging. Previous research demonstrates the considerable thermal metabolic plasticity of the cane toad, but suggests limited thermal plasticity of locomotor performance. Additionally, the oxygen-limited thermal tolerance hypothesis predicts that reduced aerobic scope sets thermal limits for ectotherm performance. Metabolic plasticity, locomotor performance and aerobic scope are therefore predicted targets of natural selection as cane toads invade colder regions. We measured these traits at temperatures of 10, 15, 22.5 and 30°C in low- and high-latitude toads acclimated to 15 and 30°C, to test the hypothesis that cane toads have adapted to cooler temperatures. High-latitude toads show increased metabolic plasticity and higher resting metabolic rates at lower temperatures. Burst locomotor performance was worse for high-latitude toads. Other traits showed no regional differences. We conclude that increased metabolic plasticity may facilitate invasion into higher latitudes by maintaining critical physiological functions at lower temperatures. PMID:27293695

  14. Preservation of layered paleodeposits in high-latitude pedestal craters on Mars

    NASA Astrophysics Data System (ADS)

    Kadish, Seth J.; Head, James W.

    2011-06-01

    An outstanding question in Mars' climate history is whether or not pedestal craters represent the armored remnants of ice-rich paleodeposits. We address this question using new high-resolution images; in a survey of several hundred high-latitude pedestal craters, we have identified 12 examples in which visible and/or topographically expressed layers are exposed on the marginal scarp of the pedestal. One example, located on the south polar layered deposits, preserves ice-rich layers that have otherwise been completely removed from the polar cap. These observations provide empirical evidence that the pedestal crater formation mechanism is capable of armoring and preserving ice-rich layered paleodeposits. Although layered exposures have not yet been observed in mid-latitude pedestal craters, high-latitude instances of discontinuous, partially covered layers suggest that layers can be readily concealed, likely through mantling and/or mass wasting processes along the marginal scarp. This interpretation is supported by the observation that high-latitude pedestals with exposed layers along their margins are, on average, taller than mid-latitude examples, and have larger, steeper marginal scarps, which may help to maintain layer exposures. These observations favor the interpretation that mid- to high-latitude pedestal craters represent the armored remnants of ice- and dust-rich paleodeposits, which occurred transiently due to changes in the climate regime. Preservation of fine-scale layering of ice and dust at these latitudes implies that the climate change did not involve regional melting conditions.

  15. A computer program for converting rectangular coordinates to latitude-longitude coordinates

    USGS Publications Warehouse

    Rutledge, A.T.

    1989-01-01

    A computer program was developed for converting the coordinates of any rectangular grid on a map to coordinates on a grid that is parallel to lines of equal latitude and longitude. Using this program in conjunction with groundwater flow models, the user can extract data and results from models with varying grid orientations and place these data into grid structure that is oriented parallel to lines of equal latitude and longitude. All cells in the rectangular grid must have equal dimensions, and all cells in the latitude-longitude grid measure one minute by one minute. This program is applicable if the map used shows lines of equal latitude as arcs and lines of equal longitude as straight lines and assumes that the Earth 's surface can be approximated as a sphere. The program user enters the row number , column number, and latitude and longitude of the midpoint of the cell for three test cells on the rectangular grid. The latitude and longitude of boundaries of the rectangular grid also are entered. By solving sets of simultaneous linear equations, the program calculates coefficients that are used for making the conversion. As an option in the program, the user may build a groundwater model file based on a grid that is parallel to lines of equal latitude and longitude. The program reads a data file based on the rectangular coordinates and automatically forms the new data file. (USGS)

  16. Variability of Winter Air Temperature in Mid-Latitude Europe

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Ardizzone, J.; Atlas, R.; Bungato, D.; Cierniewski, J.; Jusem, J. C.; Przybylak, R.; Schubert, S.; Starr, D.; Walczewski, J.

    2002-01-01

    The aim of this paper is to report extreme winter/early-spring air temperature (hereinafter temperature) anomalies in mid-latitude Europe, and to discuss the underlying forcing to these interannual fluctuations. Warm advection from the North Atlantic in late winter controls the surface-air temperature, as indicated by the substantial correlation between the speed of the surface southwesterlies over the eastern North Atlantic (quantified by a specific Index Ina) and the 2-meter level air temperatures (hereinafter Ts) over Europe, 45-60 deg N, in winter. In mid-March and subsequently, the correlation drops drastically (quite often it is negative). This change in the relationship between Ts and Ina marks a transition in the control of the surface-air temperature: absorption of insolation replaces the warm advection as the dominant control. This forcing by maritime-air advection in winter was demonstrated in a previous publication, and is re-examined here in conjunction with extreme fluctuations of temperatures in Europe. We analyze here the interannual variability at its extreme by comparing warm-winter/early-spring of 1989/90 with the opposite scenario in 1995/96. For these two December-to-March periods the differences in the monthly mean temperature in Warsaw and Torun, Poland, range above 10 C. Short-term (shorter than a month) fluctuations of the temperature are likewise very strong. We conduct pentad-by-pentad analysis of the surface-maximum air temperature (hereinafter Tmax), in a selected location, examining the dependence on Ina. The increased cloudiness and higher amounts of total precipitable water, corollary effects to the warm low-level advection. in the 1989/90 winter, enhance the positive temperature anomalies. The analysis of the ocean surface winds is based on the Special Sensor Microwave/Imager (SSM/I) dataset; ascent rates, and over land wind data are from the European Centre for Medium-Range Weather Forecasts (ECMWF); maps of 2-m temperature, cloud

  17. Aspects of wave-particle interactions at mid-latitudes

    NASA Astrophysics Data System (ADS)

    Smith, A. J.

    Arguably the most significant source of particle precipitation into the ionosphere at mid-latitudes (L ~ 2-3), at least for electrons in the tens to hundreds of keV energy range, is that which arises from the interaction between trapped particles and whistler-mode waves in the magnetosphere. Quasi-steady plasmaspheric hiss has long been postulated as a major class of waves contributing to the loss of radiation belt particles but recent studies have suggested that under some conditions, impulsive precipitation caused by interactions with lightning-generated whistlers may be equally important as a loss process. Such lightning-induced electron precipitation (LEP) and its ionospheric signature is the subject of this paper. Although LEP may be detected and studied by a variety of ground-based, balloon-borne and satellite-borne sensors, through optical emissions, X-ray production, enhanced conductivity, or the direct measurement of the precipitating particles themselves, a technique using ground-based narrow-band VLF receivers to measure the Trimpi effect (the transient perturbations in amplitude and/or phase of received narrow-band VLF transmissions) caused by LEP-associated ionisation enhancements has become increasingly popular due to its simple instrumentation and wide field of view. Most work has concentrated on the 2 < L < 3 region where typical whistler spectra, trapped electron energy distributions and magnetospheric plasma densities and magnetic field strengths are most favourable for the Trimpi effect. In order to use the technique to study in detail the characteristics and distribution of LEP (and its importance as a trapped-particle loss mechanism), using a network of intersecting transmitter-receiver great-circle paths (TRGCPs), a consensus on how to interpret the observational data is crucial, though this has recently been the subject of controversy. Whilst most studies suggest that only LEP within ~200 km of the TRGCP gives rise to an observable Trimpi

  18. High-Latitude Ionospheric Structuring at Kilometer Scales

    NASA Astrophysics Data System (ADS)

    Bust, G. S.; Datta-Barua, S.; Su, Y.; Deshpande, K.; Hampton, D.

    2014-12-01

    Ionospheric observations in the polar and auroral zones have been made regularly with radar chains and optical imaging at larger spatio-temporal cadence. However, the observation of kilometer scale variations at sub-second cadence has not been practically realizable until recently. Quantifying the irregularities at these sizes and scales is necessary for an understanding of the dynamics leading to fine scale phenomena in the high latitude environment. We present measurements of kilometer-scale plasma variations made at the northern auroral zone using an array of specialized Global Positioning System (GPS) receivers. These 6 CASES receivers (plus 1 from ASTRA, LLC) are sited at the Poker Flat Research Range, Alaska, and have been collecting data since late 2013. The array monitors for ionospheric scintillations, fluctuations in phase and amplitude of the GPS L-band signals received due to ionospheric variations. The array spans 2 km east-west and about 1 km north-south, with a variety of intermediate baseline lengths down to about 200 m. In addition to measuring amplitude and phase scintillation with the S4 and sigma_phi indices at 100-s cadence, these receivers also record 100 Hz raw power and phase measurements from GPS baseband signal processing. These low-rate data are publicly available for download through a web portal at http://apollo.tbc.iit.edu/~spaceweather/ with high rate available upon request. A detailed case study is presented from the December 8, 2013, 0300-0400 UT time period. During this period several interesting scintillation periods were observed. We use array cross-correlation processing methods to first estimate direct ground parameters of the array including a) estimate the 2D drift velocity on the ground; b) estimate a de-correlation (or turbulent) speed; and c) parameters of correlation elliptical coordinates (axial ratio and tilt angle). We then use these results and cross-correlation measurements to derive the ground 2D spatial spectrum of

  19. Intercomparison of mid latitude storm diagnostics (IMILAST) - project update

    NASA Astrophysics Data System (ADS)

    Neu, Urs

    2015-04-01

    The analysis of the occurrence of mid-latitude storms is of great socio-economical interest due to their vast and destructive impacts. However, a unique definition of cyclones is missing, and therefore the definition of what a cyclone is as well as quantifying its strength contains subjective choices. Existing automatic cyclone identification and tracking algorithms are based on different definitions and use diverse characteristics. These methods generally differ in the following aspects: data transformation (e.g., grid transformation, smoothing, etc.), metrics used for cyclone identification (e.g. sea level pressure or vorticity), cyclone identification procedures, different tracking methods (e.g. near neighborhood search), and elimination criteria (e.g., requiring a certain pressure minimum or minimum life time). The different choices made in these algorithms can lead to substantial differences in cyclone climatologies, temporal trends of the frequency, strength, or other characteristics of cyclones. The project IMILAST systematically compares different cyclone detection and tracking methods (currently 15 different algorithms), with the aim to comprehensively assess systematic uncertainties in mid-latitudinal storm identification and tracking. IMILAST uses the ERA-interim reanalysis data set as a common data basis in all studies. The first two intercomparison experiments focused on differences between the methods with respect to number, track density, life cycle characteristics, and trend patterns on the one hand and potential differences of the long-term climate change signal of cyclonic activity between the methods on the other hand. For current analysis activities, the intercomparison period is extended to a 30 year period from 1979 to 2009 and focuses on more specific aspects, such as parameter sensitivities, the comparison of automated to manual tracking sets, regional analysis (regional trends, Arctic and Antarctic cyclones, cyclones in the Mediterranean

  20. New Findings on Ice Nucleation in Mid-latitude Cirrus

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Mitchell, D. L.; Lawson, P.; Baker, B. A.

    2011-12-01

    Recent GCM simulations (CESM1) show a global aerosol indirect effect of -1.39 W m-2 with -2.02 W m-2 from shortwave and +0.63 W m-2 from longwave cloud forcing, the longwave being due to homogeneous nucleation of ice crystals. However, the extent of homogeneous nucleation in ice clouds is poorly understood. This study uses results from a recent field campaign, SPARTICUS (Small PARTicles In CirrUS), to evaluate the impact of homogeneous nucleation on the ice particle size distribution (PSD) shape, as well as ice particle concentration, shape, PSD effective size and fall speed. While earlier measurements were difficult to evaluate for ice nucleation effects due to the problem of ice particle shattering, recent in-situ measurements using the 2 dimensional-stereo (2D-S) probe have greatly reduced this problem resulting in provocative findings for both synoptic and anvil cirrus sampled during SPARTICUS. For mid-latitude synoptic and anvil cirrus around -40°C, these new measurements show that clear changes in the ice PSD and its properties occur regarding (1) PSD shape, (2) total number concentration-to-ice water content ratio (N/IWC), (3) PSD mean size, (4) PSD mean area ratio and (5) the mass-weighted fall velocity (Vm). These changes are consistent with a change in ice nucleation mechanism, with heterogeneous nucleation processes active at temperatures warmer than -40°C and homogeneous freezing nucleation at temperatures colder than -40°C. The change in Vm implies that cirrus colder than -40°C will have longer lifetimes and greater cloud coverage than warmer cirrus clouds, all other relevant factors remaining equal. The increase in N/IWC with colder temperatures (T < -40°C) appears consistent with homogeneous nucleation theory. Figure 1 shows normalized frequency distribution of PSD area ratios for temperatures above and below -40°C. Area ratios (ice particle projected area/area of circle defined by particle maximum dimension) are a measure of ice particle shape

  1. [Peculiarities of circadian rhythms in plants from different geographical latitudes].

    PubMed

    Mayer, W

    1966-09-01

    1 Two species of plants (Taraxacum arcticum and Arnica angustifolia), collected in Spitsbergen (geogr. latitude 76-80 degrees) exhibit endogenous circadian leaf movements but also movements with shorter periods. Astragalus frigidus, A. alpinus and Hedysarum hedysaroides, collected in arctic regions of continental Europe, also show endogenous diurnal leaf movements. 2. In most of the species tested, there was no difference in the length of the free running periods of plants from arctic and Central-European regions. This is also the case when individuals of the same species collected in different regions are compared. However, in Taraxacum arcticum the period is shorter than in T. officinale In general, under constant conditions the circadian oscillations of arctic plants persist for a shorter period than those of other plants. 3. The free running periods of several of the investigated species from tropical regions are much longer than 24 hours, i.e., much longer than those of species from Central-European and arctic regions. 4. The free running periods of several tropical species are temperature-independent (Erythrina senegalensis, Albizzia lophanta, Rhynchosia memmonia, Vigna catjang, Phaseolus multiflorus). In other tropical species, however, the periods decrease rather strongly with increasing temperature (Phaseolus mungo, Canavalia obtusifolia, Clitoria ternatea, Dolichos lablab, Vigna sesquipedalis, Dolichos zebra). The temperature does not influence the amplitudes in Phaseolus mungo and Vigna sesquipedalis, but it strongly influences the amplitudes in Erythrina senegalensis, in LD-cycles as well as in continuous light. 5. The arctic plant Astragalus frigidus still shows free running oscillations at 12°C, whereas several tropical species oscillate only at temperatures above 17°C. 6. The differences in the periods of tropical and non-tropical species (see under [3]) disappear if the plants are compared not at the same temperature but at temperatures which are

  2. Reconnection at the high and low latitude magnetopause

    NASA Astrophysics Data System (ADS)

    Dunlop, Malcolm; Zhang, Qinghe; Yulia, Bogdanova; Zuyin, Pu; Hiroshi, Hasegawa; Karlheinz, Trattner; Chao, Shen; Jun, Zhong; Matthew, Taylor; Jean, Berchem; Jiankui, Shi; Benoit, Lavraud; Jonathen, Eastwood; Jiansen, He; Martin, Volwerk; Andrew, Fazakerley; David, Sibeck; Dragos, Constantinescu; Harald, Frey; Philippe, Escoubet

    2013-04-01

    Recent investigations have renewed the debate on the occurrence and location of magnetic reconnection (MR) on the Earth's dayside magnetopause, where evidence exists for predominantly component driven X-line regions, independent of guide field conditions, and extending across a wide range of preferred, and often multiple, locations. Recent findings in active sites of MR have also increased the theoretical understanding of the detailed structure within the ion diffusion region surrounding the magnetic X-line or null field, although direct measurements of this small region are still relatively rare. Nevertheless, investigations have benefitted from an unprecedented growth in complexity of multi-scale and multi-point, in situ measurements, on the small and meso-scale, from, for example, the Cluster and THEMIS space missions. Furthermore, during April to July 2007 a combination of 10 spacecraft (Cluster, THEMIS and Double Star TC-1) provided simultaneous monitoring of the dayside magnetopause across a wide range of local times. Here, we first investigate repeated sampling of the ion diffusion region and associated null magnetic field of a high-latitude reconnection site by the four Cluster spacecraft flying in formation to interpret the plasma structures surrounding the X-line, which is located on initially closed field-lines and where the magnetic field orientations inside and outside the magnetopause are close to anti-parallel. The plasma populations confirm details of the ion and electron mixing, time history and acceleration through the current layer. We secondly investigate the plasma distributions near X-line structures for key conjunctions of the Cluster, THEMIS and TC-1 spacecraft around the magnetopause, showing the operation of MR at wide locations along the expected sub-solar merging line. The results are also consistent with the occurrence of reconnection activity, simultaneously across the sub-solar and flank magnetopause, linked to the (large

  3. High Latitude Energetic Particle Boundaries: The SAMPEX Database

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.

    2006-11-01

    The size of the polar cap or the open field line region depends, upon the difference in reconnection rates at the dayside between the IMF and the geomagnetic field, and those occurring in the magnetotail. The dayside merging adds flux to the open field region increasing the polar cap size and the magnetic flux in the lobes of the tail, thereby causing energy to be stored in the magnetosphere. Night side reconnection, geomagnetic storms and substorms dissipate this energy removing flux and shrink the polar cap. The dynamics of the polar cap can therefore be useful in the study of the energy dynamics of the magnetosphere. Energetic particles delineate magnetospheric regions, since their motions are governed by the geomagnetic field. Convection and corotation electric fields control the drift of low energy particles whereas magnetic field gradient and curvature are the dominant factors for higher energy (> ~30 keV) particles. High latitude energetic particle boundaries are related to the polar cap and therefore useful in determining the size of the open field line regions We will provide a long database of energetic particle boundaries in the polar regions using instruments aboard SAMPEX, the first of the Small explorer (SMEX) spacecraft. It was launched on July 3, 1992 into a low earth polar orbit. There are four particle detectors, HILT, LICA, PET and MAST on board which point toward the zenith over the poles of the Earth. These detectors measure electrons, protons and ions ranging in energy from tens of keV to a few MeV. This database will comprise the latitudinal (geographic, magnetic and invariant) and longitudinal (geographic and magnetic local time) positions of energetic particle boundaries in the polar regions. The database will cover a time period from launch to about mid 2004. It will therefore cover a significant portion of the solar cycles 22 and 23. Together with interplanetary data obtainable from public databases, such as the NASA OMNI database the

  4. A Mid-Latitude Skywave Propagation Experiment: Overview and Results

    NASA Astrophysics Data System (ADS)

    Munton, D. C.; Calfas, R. S.; Gaussiran, T., II; Rainwater, D.; Flesichmann, A. M.; Schofield, J. R.

    2016-12-01

    We will describe a mid-latitude HF skywave propagation experiment conducted during 19-27 January, 2014. There were two primary goals to the experiment. First, we wanted to build an understanding of the impact that medium scale traveling ionospheric disturbances have on the angles of arrival of the HF signals. The second goal was to provide a diverse data set that could serve as a baseline for propagation model development and evaluation. We structured individual tests during the experiment to increase the knowledge of temporal and spatial length scales of various ionospheric features. The experiment was conducted during both day and night periods and spanned a wide range of ionospheric states. We conducted the experiment at White Sands Missile Range, New Mexico and in the surrounding area. As part of the experiment, we deployed a number of active HF transmitters, and an array of dipole antennas to provide angle of arrival measurements. We also deployed a smaller array of more novel compact electro-magnetic vector sensors (EMVSs). Other instrumentation specific to the remote sensing of the ionosphere included digisondes, GNSS receivers, beacon satellite receivers, and optical instruments. We will provide a complete description of the experiment configuration and the data products.Finally, we will provide a discussion of experimental results, focusing on ionospheric conditions during the angle-of-arrival determinations, and the impact ionospheric disturbances can have on these measurements. We use the angle-of-arrival determinations to estimate TID properties, including velocity and direction.This research is based upon work supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via US Navy Contract N00024-07-D-6200. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements

  5. Northern high latitude climate variability of the last millennium

    NASA Astrophysics Data System (ADS)

    Andres, Heather J.

    This work explores the causes of northern high-latitude climate variations over the last millennium, and industrial and future periods. Attribution studies are performed on a suite of global climate simulations, and four historical reconstructions of Greenland surface temperatures and precipitation (two of which are new to this work). The simulations followed the protocols of the Palaeoclimate Modelling Intercomparison Project 3 and Coupled Model Intercomparison Project 5. At least half of the multi-decadal variability in simulated Greenland climate variations over the last millennium is reproduced by a linear, empirically-generated model including terms for volcanic emissions, solar insolation changes (including total solar irradiance and orbital components) and an index associated with latitudinal shifts in the North Atlantic jet. Empirical model parameters are obtained by regressing simulated Greenland temperatures and precipitation against time series for each of the response variables. Greenhouse gas radiative forcing changes are unimportant to simulated Greenland conditions over the last millennium, although they dominate after the mid-20th century. Most of the historical Greenland climate reconstructions are restricted to the industrial period, due to a lack of spatially-comprehensive climate records. They exhibit substantial differences in the timing, phasing and amplitudes of past climate variations, due to regional sensitivities in the source data and the reconstruction methodologies. Reconstructions indicate that Greenland temperatures did not begin to follow hemispheric greenhouse gas warming patterns until the mid-1990s. This discrepancy indicates either that the warming hiatus was associated with internal climate variability, or that the simulations are missing processes important to Greenland climate. For example, indirect effects of anthropogenic aerosols are not captured in the climate model employed here. All of the external climate forcings

  6. Possible Triggering of Solar Activities to Big Earthquakes (Ms>=8) in the Middle Latitude in China

    NASA Astrophysics Data System (ADS)

    Su, Tong-Wei; Li, Ke-Jun

    2007-06-01

    The relationship between solar activities and big earthquakes (Ms>=8) that occured in middle latitudes (20°<=latitude<=40°) in China is studied in this paper. It is found that the occurence dates of most of the big earthquakes are close to the descendent years to minimum years of sunspot numbers, and it implies the correlation between solar activities and earthquakes. Occurence of large flood in the middle latitude is negatively correlated with solar activity. The rainfall result in rise of water level. Perhaps the gestated big earthquakes occur easily since the rocks are dipped in groundwater and therefore decreases the shear resistant intensity of rocks.

  7. In situ measurements constraining the role of sulphate aerosols in mid-latitude ozone depletion

    NASA Technical Reports Server (NTRS)

    Fahey, D. W.; Kawa, S. R.; Woodbridge, E. L.; Tin, P.; Wilson, J. C.; Jonsson, H. H.; Dye, J. E.; Baumgardner, D.; Borrmann, S.; Toohey, D. W.

    1993-01-01

    In situ measurements of stratospheric sulphate aerosol, reactive nitrogen and chlorine concentrations at middle latitudes confirm the importance of aerosol surface reactions that convert active nitrogen to a less active, reservoir form. This makes mid-latitude stratospheric ozone less vulnerable to active nitrogen and more vulnerable to chlorine species. The effect of aerosol reactions on active nitrogen depends on gas phase reaction rates, so that increases in aerosol concentration following volcanic eruptions will have only a limited effect on ozone depletion at these latitudes.

  8. Modeling the effects of snowpack on heterotrophic respiration across northern temperate and high latitude regions: Comparison with measurements of atmospheric carbon dioxide in high latitudes

    USGS Publications Warehouse

    McGuire, A.D.; Melillo, J.M.; Randerson, J.T.; Parton, W.J.; Heimann, Martin; Meier, R.A.; Clein, J.S.; Kicklighter, D.W.; Sauf, W.

    2000-01-01

    Simulations by global terrestrial biogeochemical models (TBMs) consistently underestimate the concentration of atmospheric carbon dioxide (CO2) at high latitude monitoring stations during the nongrowing season. We hypothesized that heterotrophic respiration is underestimated during the nongrowing season primarily because TBMs do not generally consider the insulative effects of snowpack on soil temperature. To evaluate this hypothesis, we compared the performance of baseline and modified versions of three TBMs in simulating the seasonal cycle of atmospheric CO2 at high latitude CO2 monitoring stations; the modified version maintained soil temperature at 0 ??C when modeled snowpack was present. The three TBMs include the Carnegie-Ames-Stanford Approach (CASA), Century, and the Terrestrial Ecosystem Model (TEM). In comparison with the baseline simulation of each model, the snowpack simulations caused higher releases of CO2 between November and March and greater uptake of CO2 between June and August for latitudes north of 30??N. We coupled the monthly estimates of CO2 exchange, the seasonal carbon dioxide flux fields generated by the HAMOCC3 seasonal ocean carbon cycle model, and fossil fuel source fields derived from standard sources to the three-dimensional atmospheric transport model TM2 forced by observed winds to simulate the seasonal cycle of atmospheric CO2 at each of seven high latitude monitoring stations, in comparison to the CO2 concentrations simulated with the baseline fluxes of each TBM, concentrations simulated using the snowpack fluxes are generally in better agreement with observed concentrations between August and March at each of the monitoring stations. Thus, representation of the insulative effects of snowpack in TBMs generally improves simulation of atmospheric CO2 concentrations in high latitudes during both the late growing season and nongrowing season. These simulations highlight the global importance of biogeochemical processes during the

  9. Evidence for magma recharge and cumulate assimilation within the Fossa delle Felci (Salina Island, Italy) volcanic sequence

    NASA Astrophysics Data System (ADS)

    Mayfield, A. M.; Bohrson, W. A.; Hunt, R.; Creamer, J. B.

    2011-12-01

    Integrating plagioclase in situ chemical and textural analyses with MELTS (Ghiorso & Sack 1995) provides quantitative information about magma chamber processes such as recharge (R), assimilation (A) and fractional crystallization (FC) and constrains variables such as pressure, temperature and water content. Studies on Salina Island have documented volcanic sequences ranging from basalt to rhyolite that erupted between ~500-13 ka (Gertisser & Keller 2000). In the Fossa delle Felci sequence, basalts to basaltic andesites (herein called basalt) are the lowest units in the series followed upsection by dacite, andesite and basaltic andesite. Thirteen samples were chosen for whole rock major and trace element and Sr isotope analysis with a subset of six representative samples chosen for in situ textural and chemical analysis. The basalt shows the least complex plagioclase textures, as documented by Nomarski Differential Interference Contrast imaging. Textural complexity increases with increasing whole rock SiO2. No overlap occurs in core and rim anorthite (An mol%) values for the basalt, with varying degrees of overlap in core and rim An values for the remaining samples. The An range for all crystals is 93-39. Whole rock major and trace elements show systematic trends suggesting differentiation controlled by FC. The basalt displays anomalously high Al2O3, CaO and low MgO. For most samples, whole rock Sr behaves compatibly, but two andesites have anomalously high [Sr]. Overall, in situ plagioclase [Sr] range from 918-2312 ppm with the lowest values in the basalt and the highest in the dacite. Whole rock 87Sr/86Sr range from 0.70475-0.70433. Basaltic andesites are the least radiogenic, and andesites are the most radiogenic; thus, there are no simple correlations with indices of differentiation. Preliminary in situ LA-ICPMS analyses of one andesite yield 87Sr/86Sr of 0.70439-0.70408 with values decreasing rimward; all in situ values are lower than the whole rock value

  10. [Characteristics in a sample of criminal mental hospital (Castiglione delle Stiviere) inmates discharged in the Lazio region].

    PubMed

    Cerboneschi, Annalisa; Bensi, Marco; Brandizzi, Martina; Dario, Claudia; Fagioli, Marcella; Fiori Nastro, Paolo

    2009-01-01

    AIM. The aim of this study was: (i) To identify socio-demographic and clinical data in a sample of inmates in the Criminal Mental Hospital (CMH) at Castiglione delle Stiviere; (ii) to assess the presence of characteristics which could foresee the commission of a crime of psychiatric interest; (iii) to assess the frequency of crime repetition. This study was carried out on a sample of 38 patients. A descriptive analysis of the sample was carried out and the associations among several variables were analyzed. The sample is characterized by a high frequency of schizophrenia diagnosis (73.0%), the presence of hospitalization before the commission of the crime (68.4%) and the absence of criminal precedents (71.1%). For men the age of the commission of the crime is equal to 33.72 +/- 10.6 years and for women to 45.18 +/- 11.4 years (p = 0.011). The time between the onset and the commission of the crime is longer in patients who have received therapy (treatment) than in those ones with no treatment (p = 0.012). About 12% of the sample committed new crimes. The results showed previous criminal acts are not predictive for the commission of new crimes of psychiatric interest. However many patients had previous contacts with community facilities before their first admission to hospital and the treatment extended the interval between the onset of the disease and the commission of the crime. The relapse rate after the discharge was very low if compared with samples coming from other services that offered more custodial rather than rehabilitative facilities.

  11. Preference and performance in plant-herbivore interactions across latitude--a study in U.S. Atlantic salt marshes.

    PubMed

    Ho, Chuan-Kai; Pennings, Steven C

    2013-01-01

    High-latitude plants are often more palatable to herbivores than low-latitude conspecifics. Does increased plant palatability lead to better herbivore performance? Our field and laboratory work investigated (A) whether high-latitude plants have traits indicating that they should be higher-quality foods for herbivores; (B) whether geographic differences in plant quality are more important than local adaptation of herbivores. We studied 3 plant species and 6 invertebrate herbivores in U.S. Atlantic Coast. Past studies had shown high-latitude individuals of these plants are more palatable than low-latitude conspecifics. We documented plant traits and herbivore performance (body size) in the field across latitude. We collected individuals from different latitudes for factorial (plant region x herbivore region) laboratory experiments, examining how herbivore performance was affected by plant region, herbivore region, and their interaction (i.e., local adaptation). Field surveys suggested high-latitude plants were likely of higher quality to herbivores. Leaf nitrogen content in all plant species increased toward high latitudes, consistent with lower leaf C/N and higher leaf chlorophyll content at high latitudes. Furthermore, leaf toughness decreased toward higher latitudes in 1 species. The body size of 4 herbivore species increased with latitude, consistent with high-latitude leaves being of higher quality, while 2 grasshopper species showed the opposite pattern, likely due to life-history constraints. In the laboratory, high-latitude plants supported better performance in 4 herbivore species (marginal in the 5th). The geographic region where herbivores were collected affected herbivore performance in all 6 species; however, the pattern was mixed, indicating a lack of local adaptation by herbivores to plants from their own geographic region. Our results suggest that more-palatable plants at high latitudes support better herbivore growth. Given that geographic origin of

  12. Cantico Delle Creature: A microtonal original composition for soprano and string quartet to a text by St. Francis of Assisi, including analytical commentary

    NASA Astrophysics Data System (ADS)

    Sabol, Jason A.

    Cantico delle Creature is an original piece of music for soprano and string quartet composed in 72 tone per octave equal temperament, dividing each semitone into six equal parts called twelfth-tones. This system of tuning makes it possible to combine just intonation and spectral principles based on the harmonic series with real imitation, modulation, and polyphony. Supplemental text discusses several aspects of microtonal structure and pedagogy, including the representation of the first 64 partials of the harmonic series in 72 tone equal temperament, performance of natural string harmonics, the relationship between interval size and vibration ratio, pitch to frequency conversion, and analysis of several passages in the musical score.

  13. Bringing feedback and resilience of high-latitude ecosystems into the corporate boardroom.

    PubMed

    Whiteman, Gail; Forbes, Bruce C; Niemelä, Jari; Chapin, F Stuart

    2004-08-01

    This paper discusses the role of companies in high-latitude regions, which are conceptualized as socially and economically mediated ecosystems, and identifies a number of important social actors within the business environment. We present three examples of corporate activity at high latitudes and discuss a variety of common threads. Notably, we argue that business theory and practice needs to move beyond a narrow social or economic concept of organizational resilience and embrace the ecological resilience of high-latitude regions as a business management goal. We also suggest that regional ecosystem resilience needs to become a meaningful measure of sustainable corporate governance, one that corporate boards of directors can review and commit to. The paper concludes with a call for a detailed research agenda on the role of transnational and national companies within high-latitude regions.

  14. Lean production tools and decision latitude enable conditions for innovative learning in organizations: a multilevel analysis.

    PubMed

    Fagerlind Ståhl, Anna-Carin; Gustavsson, Maria; Karlsson, Nadine; Johansson, Gun; Ekberg, Kerstin

    2015-03-01

    The effect of lean production on conditions for learning is debated. This study aimed to investigate how tools inspired by lean production (standardization, resource reduction, visual monitoring, housekeeping, value flow analysis) were associated with an innovative learning climate and with collective dispersion of ideas in organizations, and whether decision latitude contributed to these associations. A questionnaire was sent out to employees in public, private, production and service organizations (n = 4442). Multilevel linear regression analyses were used. Use of lean tools and decision latitude were positively associated with an innovative learning climate and collective dispersion of ideas. A low degree of decision latitude was a modifier in the association to collective dispersion of ideas. Lean tools can enable shared understanding and collective spreading of ideas, needed for the development of work processes, especially when decision latitude is low. Value flow analysis played a pivotal role in the associations.

  15. Understanding the Latitude Structure of Nitric Oxide in the Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Fuller-Rowell, T.J.

    1997-01-01

    The goal of the proposed work was to understand the latitude structure of nitric oxide in the mesosphere and lower thermosphere. The problem was portrayed by a clear difference between predictions of the nitric oxide distribution from chemical/dynamical models and data from observations made by the Solar Mesosphere Explorer (SMEE) in the early to mid eighties. The data exhibits a flat latitude structure of NO, the models tend to produce at equatorial maximum. The first task was to use the UARS-HALOE data to confirm the SME observations. The purpose of this first phase was to verify the UARS-NO structure is consistent with the SME data. The next task was to determine the cause of the discrepancy between modeled and observed nitric oxide latitude structure. The result from the final phase indicated that the latitude structure in the Photo-Electron (PE) production rate was the most important.

  16. High-latitude ionospheric model - First step towards a predictive capability

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Raitt, W. J.; Sojka, J. J.

    1981-01-01

    In order to study the plasma density features associated with both weak and strong convection in the winter high-latitude F-region, a simple plasma convection model was combined with an ionospheric-atmospheric composition model. In a model calculation, a field tube of plasma is followed as it moves along a convection trajectory through a moving, neutral atmosphere. The altitude profiles of the ion densities are obtained by solving the appropriate continuity, momentum and energy equations, including many high-latitude processes. The result of following many such plasma field tubes is a time-dependent, three-dimensional ion density distribution for the ions NO(+), O2(+), O(+), N(+), and He(+). The high-latitude ionosphere is covered over one complete day above 42 deg N magnetic latitude, at altitudes of 160-800 km.

  17. Calculated nighttime eastward plasma drift velocities at low latitudes and their solar cycle dependence

    NASA Technical Reports Server (NTRS)

    Anderson, D. N.; Heelis, R. A.; Mcclure, J. P.

    1987-01-01

    After calculating ambient electron densities as a function of altitude, latitude and local time, a simplified expression is used to calculate F-region eastward plasma drifts given a zonal neutral wind model. The derived eastward plasma drift on a magnetic flux tube is examined as a function of the flux tube apex height. If the neutral wind is assumed to be independent of latitude the plasma drift maximizes along the flux tube which intercepts the F-region peak concentration at the Appleton anomaly. Above this altitude the velocity decreases to reflect a decrease in the flux tube integrated F-region Pedersen conductivity. For a latitude dependent wind the plasma drift tends to maximize along the flux tube which intercepts the F-peak at the dip equator. Above this altitude the drift decreases to reflect the latitude distribution of the wind.

  18. Plasma density features associated with strong convection in the winter high-latitude F region

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Raitt, W. J.; Schunk, R. W.

    1981-01-01

    A single plasma convection model was combined with an ionospheric-atmospheric composition model to study plasma density features associated with string convection in the winter high-latitude F region. Time dependent, three-dimensional, ion density distributions for NO(+), O2(+), N2(+), O(+) and He(+) were produced, and the ionosphere above 42 deg N magnetic latitude was covered for 24 hours. The study found that for strong and weak convection, electron density exhibited a variation with altitude, latitude, longitude and universal time. Ionospheric features were evident for strong convection, but modified in comparison with those found for slow convection. Also found for strong convection was a more pronounced tongue of ionization, the appearance of a new polar hole in the polar cap, and a midlatitude electron density trough that was not as deep as found for a weak convection. In addition, good agreement was found between predictions and Atmosphere Explorer measurements of ion composition variation with latitude and local time.

  19. Can genetically based clines in plant defence explain greater herbivory at higher latitudes?

    PubMed

    Anstett, Daniel N; Ahern, Jeffrey R; Glinos, Julia; Nawar, Nabanita; Salminen, Juha-Pekka; Johnson, Marc T J

    2015-12-01

    Greater plant defence is predicted to evolve at lower latitudes in response to increased herbivore pressure. However, recent studies question the generality of this pattern. In this study, we tested for genetically based latitudinal clines in resistance to herbivores and underlying defence traits of Oenothera biennis. We grew plants from 137 populations from across the entire native range of O. biennis. Populations from lower latitudes showed greater resistance to multiple specialist and generalist herbivores. These patterns were associated with an increase in total phenolics at lower latitudes. A significant proportion of the phenolics were driven by the concentrations of two major ellagitannins, which exhibited opposing latitudinal clines. Our analyses suggest that these findings are unlikely to be explained by local adaptation of herbivore populations or genetic variation in phenology. Rather greater herbivory at high latitudes can be explained by latitudinal clines in the evolution of plant defences. © 2015 John Wiley & Sons Ltd/CNRS.

  20. Unambiguous evidence of HF pump-enhanced airglow at auroral latitudes

    NASA Astrophysics Data System (ADS)

    Brändström, B. U. E.; Leyser, T. B.; Steen, Å.; Rietveld, M. T.; Gustavsson, B.; Aso, T.; Ejiri, M.

    1999-12-01

    Simultaneous observations by up to three low-light imaging stations belonging to the Auroral Large Imaging System (ALIS) have provided the first strong evidence of high-frequency (HF) pump-enhanced airglow at auroral latitudes. The airglow was enhanced by an ordinary mode 4.04 MHz electromagnetic wave with an effective radiated power (ERP) of about 210 MW that was transmitted from the EISCAT-Heating facility near Tromsø, Norway. While often observed at low or mid-latitudes, and despite numerous earlier experiments, no unambiguous observations of pump-enhanced airglow have been reported at auroral latitudes. On February 16, 1999, the first successful results were obtained, and this paper concentrates on discussing optical data from this event. Triangulated estimations of the altitude and position of the enhanced airglow are also presented. Auroral-latitude observations of HF pump-enhanced airglow are important in order to better understand the underlying excitation mechanisms.

  1. Ulysses Radio and Plasma Wave Observations at High Southern Heliographic Latitudes

    NASA Astrophysics Data System (ADS)

    Stone, R. G.; MacDowall, R. J.; Fainberg, J.; Hoang, S.; Kaiser, M. L.; Kellogg, P. J.; Lin, N.; Osherovich, V. A.; Bougeret, J. L.; Canu, P.; Cornilleau-Wehrlin, N.; Desch, M. D.; Goetz, K.; Goldstein, M. L.; Harvey, C. C.; Lengyel-Frey, D.; Manning, R.; Reiner, M. J.; Steinberg, J. L.; Thejappa, G.

    1995-05-01

    Ulysses spacecraft radio and plasma wave observations indicate that some variations in the intensity and occurrence rate of electric and magnetic wave events are functions of heliographic latitude, distance from the sun, and phase of the solar cycle. At high heliographic latitudes, solar type III radio emissions did not descend to the local plasma frequency, in contrast to the emission frequencies of some bursts observed in the ecliptic. Short-duration bursts of electrostatic and electromagnetic waves were often found in association with depressions in magnetic field amplitude, known as magnetic holes. Extensive wave activity observed in magnetic clouds may exist because of unusually large electron-ion temperature ratios. The lower number of intense in situ wave events at high latitudes was likely due to the decreased variability of the high-latitude solar wind.

  2. Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere.

    PubMed

    Keppler, E; Fränz, M; Korth, A; Reuss, M K; Blake, J B; Seidel, R; Quenby, J J; Witte, M

    1995-05-19

    Measurements with the Energetic Particle Composition instrument (EPAC) aboard Ulysses show particles from near the ecliptic that were apparently accelerated by shocks associated with a corotating interaction region. The particles were detected together with the shocks and even when shocks no longer arrived at Ulysses up to -65 degrees of heliographic latitude but not beyond. Particles could have reached these latitudes along magnetic fields; such connections to the outer lower latitude heliosphere evidently do not exist above that latitude. The accelerated streams have composition similar to solar wind abundances, no dispersion, and a net inward anisotropy. The underlying composition between the recurrent stream is similar to the anomalous component of cosmic rays. The channel sensitive to high-energy protons (> 230 megaelectron volts) shows a 26-day variation of the flux superimposed on the heliospheric modulation of galactic ions.

  3. A simplified indexing of F-region geophysical noise at low latitudes

    NASA Technical Reports Server (NTRS)

    Aggarwal, S.; Lakshmi, D. R.; Reddy, B. M.

    1979-01-01

    A simple method of deriving an F-region index that can warn the prediction users at low latitudes as to the specific months when they have to be more careful in using the long term predictions is described.

  4. Ulysses radio and plasma wave observations at high southern heliographic latitudes.

    PubMed

    Stone, R G; Macdowall, R J; Fainberg, J; Kaiser, M L; Desch, M D; Goldstein, M L; Hoang, S; Bougeret, J L; Harvey, C C; Manning, R; Steinberg, J L; Kellogg, P J; Lin, N; Goetz, K; Osherovich, V A; Reiner, M J; Canu, P; Cornilleau-Wehrlin, N; Lengyel-Frey, D; Thejappa, G

    1995-05-19

    Ulysses spacecraft radio and plasma wave observations indicate that some variations in the intensity and occurrence rate of electric and magnetic wave events are functions of heliographic latitude, distance from the sun, and phase of the solar cycle. At high heliographic latitudes, solartype Ill radio emissions did not descend to the local plasma frequency, in contrast to the emission frequencies of some bursts observed in the ecliptic. Short-duration bursts of electrostatic and electromagnetic waves were often found in association with depressions in magnetic field amplitude, known as magnetic holes. Extensive wave activity observed in magnetic clouds may exist because of unusually large electron-ion temperature ratios. The lower number of intense in situ wave events at high latitudes was likely due to the decreased variability of the high- latitude solar wind.

  5. High prevalence and no latitude gradient of multiple sclerosis in Norway.

    PubMed

    Berg-Hansen, P; Moen, S M; Harbo, H F; Celius, E G

    2014-11-01

    The prevalence of multiple sclerosis (MS) is increasing, and the presence of a latitude gradient for MS risk is still discussed. We present the first nationwide prevalence estimates for Norway, spanning the latitudes from 58-71 degrees North, in order to identify a possible latitude gradient. Information from the Oslo MS Registry and the Norwegian MS Registry and Biobank was combined with data from the Norwegian Patient Registry, the Norwegian Prescription Database and Statistics Norway. We estimated a crude prevalence of 203/100,000 on 1 January 2012. The prevalence in the Northern and Southern regions were not significantly different. MS prevalence in Norway is among the highest reported worldwide. We found no evidence of a latitude gradient.

  6. Mesopheric Temparature Inversions Observed in Long-Term Lidar Measurements at Mid- and Low-Latitudes

    NASA Technical Reports Server (NTRS)

    Leblanc, T.; McDermid, I. S.; Keckhut, P.; Hauchecorne, A.

    1998-01-01

    Results of an investigation of mesospheric temperature inversion layers using long-term lidar measurements at mid- and low-latitudes are reported. In this paper, new results from different lidar observations of the invasion layers will be presented.

  7. Mesopheric Temparature Inversions Observed in Long-Term Lidar Measurements at Mid- and Low-Latitudes

    NASA Technical Reports Server (NTRS)

    Leblanc, T.; McDermid, I. S.; Keckhut, P.; Hauchecorne, A.

    1998-01-01

    Results of an investigation of mesospheric temperature inversion layers using long-term lidar measurements at mid- and low-latitudes are reported. In this paper, new results from different lidar observations of the invasion layers will be presented.

  8. Radiative Forcing of the Pinatubo Aerosol as a Function of Latitude and Time

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Kinne, S.; Russell, P. B.; Bauman, J. J.; Minnis, P.

    1996-01-01

    We present calculations of the radiative forcing of the Mt. Pinatubo aerosols as a function of latitude and time after the eruption and compare the results with GOES satellite data. The results from the model indicate that the net effect of the aerosol was to cool the earth-atmosphere system with the most significant radiative effect in the tropics (corresponding to the location of the tropical stratospheric reservoir) and at latitudes greater than 60 deg. The high-latitude maximum is a combined effect of the high-latitude peak in optical depth (Trepte et al 1994) and the large solar zenith angles. The comparison of the predicted and measured net flux shows relatively good agreement, with the model consistently under predicting the cooling effect of the aerosol.

  9. Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes.

    PubMed

    Prevéy, Janet; Vellend, Mark; Rüger, Nadja; Hollister, Robert D; Bjorkman, Anne D; Myers-Smith, Isla H; Elmendorf, Sarah C; Clark, Karin; Cooper, Elisabeth J; Elberling, Bo; Fosaa, Anna M; Henry, Gregory H R; Høye, Toke T; Jónsdóttir, Ingibjörg S; Klanderud, Kari; Lévesque, Esther; Mauritz, Marguerite; Molau, Ulf; Natali, Susan M; Oberbauer, Steven F; Panchen, Zoe A; Post, Eric; Rumpf, Sabine B; Schmidt, Niels M; Schuur, Edward A G; Semenchuk, Phillip R; Troxler, Tiffany; Welker, Jeffrey M; Rixen, Christian

    2017-01-11

    Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. To test this hypothesis, we examined up to 20 years of phenology data for 47 tundra plant species at 18 high-latitude sites along a climatic gradient. Across all species, the timing of leaf emergence and flowering was more sensitive to a given increase in summer temperature at colder than warmer high-latitude locations. A similar pattern was seen over time for the flowering phenology of a widespread species, Cassiope tetragona. These are among the first results highlighting differential phenological responses of plants across a climatic gradient and suggest the possibility of convergence in flowering times and therefore an increase in gene flow across latitudes as the climate warms.

  10. The latitude dependencies of the solar wind. [of interplanetary magnetic field polarity and configurations

    NASA Technical Reports Server (NTRS)

    Rosenberg, R. L.; Winge, C. R., Jr.

    1974-01-01

    The motion of spacecraft following the earth's orbit occurs within the solar latitude range of 7 deg 15 min N on approximately September 7 to 7 deg 15 min S on approximately March 6. The latitude dependencies so far detected within this range have shown that the photospheric dipole-like field of the sun makes very important contributions to the interplanetary magnetic field (IMF) observed near the ecliptic. Changes in geomagnetic activity from even to odd numbered 11-year solar cycles are related to changes in the sun's dipolar field. The north-south IMF component and meridional, nonradial flow are important to a complete understanding of steady-state solar wind dynamics. Coronal conditions must be latitude-dependent in a way that accounts for the observed latitude dependence of the velocity and density of the solar wind.

  11. HIGH-LATITUDE SOLAR TORSIONAL OSCILLATIONS DURING PHASES OF CHANGING MAGNETIC CYCLE AMPLITUDE

    SciTech Connect

    Rempel, M.

    2012-05-01

    Torsional oscillations are variations of the solar differential rotation that are strongly linked to the magnetic cycle of the Sun. Helioseismic inversions have revealed significant differences in the high-latitude branch of torsional oscillations between cycle 23 and cycle 24. Here we employ a non-kinematic flux-transport dynamo model that has been used previously to study torsional oscillations and simulate the response of the high-latitude branch to a change in the amplitude of the magnetic cycle. It is found that a reduction of the cycle amplitude leads to an increase in the amplitude of differential rotation that is mostly visible as a drop in the high-latitude rotation rate. Depending on the amplitude of this adjustment the high-latitude torsional oscillation signal can become temporarily hidden due to the unknown changing mean rotation rate that is required to properly define the torsional oscillation signal.

  12. Are lower-latitude plants better defended? Palatability of freshwater macrophytes.

    PubMed

    Morrison, Wendy E; Hay, Mark E

    2012-01-01

    Increased herbivory at lower latitudes is hypothesized to select for more effective plant defenses. Feeding assays with seaweeds and salt marsh plants support this hypothesis, with low-latitude plants experiencing greater damage in the field and being less palatable than higher-latitude plants. We tested this hypothesis for freshwater macrophytes because they offered an independent plant lineage and habitat type for testing this general hypothesis and because the patchiness of consumer occupancy across isolated water bodies might produce local variance in herbivory that would override geographic variance and produce different results for this habitat type. When we fed eight congeneric pairs of live plants from four sites in Indiana vs. four sites in South Florida (-215 and 0 frost days/yr respectively) to three species of crayfishes and one species of snail, three of the four herbivores significantly preferred high-latitude to low-latitude plants. For two crayfishes that differed in feeding on live plants (one favoring high-latitude plants and one not), we retested feeding using foods composed of freeze-dried and finely ground plants, thus removing structural characteristics while retaining most chemical/nutritional traits. In this assay, both herbivores strongly preferred high-latitude plants, suggesting that lower-latitude plants had been selected for more deterrent chemical traits. When we collected 22 pairs of congeneric plants from 9 sites throughout Indiana vs. 13 sites in Central Florida (-215 and -95 frost days/yr respectively) and tested these in feeding assays with three crayfishes using dried, ground, and reconstituted plant material, we found a significant effect of latitude for only one of three species of herbivore. Overall, our results suggest a preference for high-latitude plants, but the strength of this relationship varied considerably across small scales of latitude that differed considerably in numbers of frost-free days. The difference in

  13. Why are nitrogen-fixing trees rare at higher compared to lower latitudes?

    PubMed

    Menge, Duncan N L; Batterman, Sarah A; Hedin, Lars O; Liao, Wenying; Pacala, Stephen W; Taylor, Benton N

    2017-10-04

    Symbiotic nitrogen (N) fixation provides a dominant source of new N to the terrestrial biosphere, yet in many cases the abundance of N-fixing trees appears paradoxical. N-fixing trees, which should be favored when N is limiting, are rare in higher-latitude forests where N limitation is common, but are abundant in lower-latitude forests where N limitation is rare. Here, we develop a graphical and mathematical model to resolve the paradox. We use the model to demonstrate that N fixation is not necessarily cost-effective under all degrees of N limitation, as intuition suggests. Rather, N fixation is only cost-effective when N limitation is sufficiently severe. This general finding, specific versions of which have also emerged from other models, would explain sustained moderate N limitation because N-fixing trees would either turn N fixation off or be outcompeted under moderate N limitation. From this finding, four general hypothesis classes emerge to resolve the apparent paradox of N limitation and N-fixing tree abundance. The first hypothesis is that N limitation is less common at higher latitudes. This hypothesis contradicts prevailing evidence, so is unlikely, but the following three hypotheses all seem likely. The second hypothesis, which is new, is that even if N limitation is more common at higher latitudes, more severe N limitation might be more common at lower latitudes because of the capacity for higher N demand. Third, N fixation might be cost-effective under milder N limitation at lower latitudes but only under more severe N limitation at higher latitudes. This third hypothesis class generalizes previous hypotheses and suggests new specific hypotheses. For example, greater tradeoffs between N fixation and N use efficiency, soil N uptake, or plant turnover at higher compared to lower latitudes would make N fixation cost-effective only under more severe N limitation at higher latitudes. Fourth, N-fixing trees might adjust N fixation more at lower than at

  14. Performance Statistics Bulletin High Latitude Meteor Scatter Propagation February, March, April, May 1992

    DTIC Science & Technology

    1994-02-02

    High Latitude Meteor Scatter Performance Statistics 1. INTRODUCTION This bulletin presents a summary of results obtained from the Phillips Laboratory...on a common scale. "**Earlier practice displayed noise at all frequencies on a common linear scale, resulting in occasional confusion from overlapping...plots presenting data at 35 and 45 MHz. since E. propagation may frequently dominate at polar cap latitudes, resulting in gaps in the data that are

  15. Quantifying Transport Between the Tropical and Mid-Latitude Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Volk, C.; Elkins, J.; Fahey, D.; Salawitch, R.; Dutton, G.; Gilligan, J.; Proffitt, M.; Loewenstein, M.; Podolske, J.; Minschwaner, K.; hide

    1996-01-01

    Because exchange with the tropics is slower than multi-dimensional models generally assume, ozone at mid-latitudes apears to be more sensitive to elevated levels of industrial chlorine than currently predicted. Nevertheless, approximately 45% of air in the tropical ascent region at 21 km has been entrained from mid-latitudes, implying that emissions from supersonic aircraft could deplete ozone in the middle stratosphere.

  16. Potential for Expansion of Coral Reefs into Higher Latitudes due to Climate Change

    DTIC Science & Technology

    2003-09-01

    SEP 2003 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Potential for Expansion of Coral Reefs into Higher Latitudes due to...ANSI Std Z39-18 0-933957-31-9 P2745 Potential for Expansion of Coral Reefs into Higher Latitudes due to Climate...investigate if there have been any effects on Sea Surface Temperature (SST) at geographical margins of coral reefs . It is generally accepted that

  17. The Multipath and Fading Profile of the High Latitude Meteor Burst Communication Channel.

    DTIC Science & Technology

    1986-10-01

    APPROVED: j~ ~ e. c ALLAN C. SCHELL Chief, Electromagnetic Sciences Division FOR THE COMMANDER: [ JOHN A. RITZ - Plans and Programs Division *, If your...multipath measurement VHF propagation / 19 ABSTRACT (Continue on reverse ,f necessary and identify by block number) ------ ------ .. tion High...latitude propagation phenomenon such as scatter from the aurora and sporadic-E propagation can alter the communication characteristics of the high latitude

  18. Performance Statistics Bulletin. High Latitude Meteor Scatter Propagation June, July, August, September 1990

    DTIC Science & Technology

    1994-01-26

    the scattering geometry, or if they are caused by two independent meteorites with entirely different paths. 6 METEORIC 890307 040504 45MHZ METEORIC ...AD-A276 695 PL-TIR-94..2024 Environmental Research Papers, No. 1143 PERFORMANCE STATISTICS BULLETIN HIGH LATITUDE METEOR SCATTER PROPAGATION JUNE...AND DATES COVERED 26 Jamary 1994 Scientific interim 4. TITLE AND SUBTITLE S. FUNDING NUMBERS Performance Statistics Bulletin High Latitude Meteor

  19. Performance Statistics Bulletin. High Latitude Meteor Scatter Propagation, November, December 1989, and January 1990

    DTIC Science & Technology

    1993-11-22

    Guide . GL Tech. Rep. GL-TR-89-O1 54, ADA214988. 4. Weitzen, J.A. and Tolman, S., (1986) A Technigue for Automatic Classification of Meteor Trails and...AD-A276 688 PL-TR-93-2234 Environmental Research Papers, No. 1133 PERFORMANCE STATISTICS BULLETIN HIGH LATITUDE METEOR SCATTER PROPAGATION NOVEMBER...FUNDING NUMBERS Performance Statistics Bulletin H;ih Latitude Meteor Scatter Propagation PE 62101F November. December 1989, and January 1990 PR 4643

  20. A statistical approach to latitude measurements: Ptolemy's and Riccioli's geographical works as case studies

    NASA Astrophysics Data System (ADS)

    Santoro, Luca

    2017-08-01

    The aim of this work is to analyze latitude measurements typically used in historical geographical works through a statistical approach. We use two sets of different age as case studies: Ptolemy's Geography and Riccioli's work on geography. A statistical approach to historical latitude and longitude databases can reveal systematic errors in geographical georeferencing processes. On the other hand, once exploiting the right statistical analysis, this approach can also lead to new information about ancient city locations.

  1. Why Do Model Tropical Cyclones Intensify More Rapidly at Low Latitudes?

    DTIC Science & Technology

    2015-05-01

    low latitudes. The answer to this question touches on practically all facets of the dynamics and thermodynamics of tropical cyclones. The answer invokes...practically all facets of the dynamics and thermodynamics of tropical cyclones. The answer invokes the conventional spin-up mechanism, as articulated in...the dependence of the intensification rate and mature intensity on latitude touches on practically all facets of the dynamics and thermodynamics of

  2. Latitudinal TEC gradients over polar ionosphere using high latitude GPS measurements

    NASA Astrophysics Data System (ADS)

    Shagimuratov, Irk; Cherniak, Iurii; Zakharenkova, Irina; Tepenitsyna, Nadezhda; Yakimova, Galina; Ephishov, I. I.

    The GPS observations of Greenland network were used to analyze the latitudinal variations of TEC at the high-latitudes ionosphere. This network provides unique opportunity to monitor TEC variability in polar ionosphere on a regular base. GPS stations are arranged along the latitude over the range 60-83°N (65°-87° Corrected Geomagnetic Latitude) near of 30°-40° longitudes. More than 20 GPS stations are located closely with one another along latitude. The distance between stations is about 1°-2°.Such spatial resolution provides the possibility to analyze the detailed structure of latitudinal TEC profiles. The standard procedure of processing GPS observations was used for TEC estimation. On this base it was obtained the diurnal TEC variations over all Greenland stations. The TEC data is used to form latitudinal profiles (TEC section) covered subauroral, auroral and polar ionosphere. In the report the observations of TEC for quiet and disturbed ionosphere during several geomagnetic storms occurred in September 2011 are presented. During quiet conditions in the night-time TEC profiles demonstrated invariable values about of 4-6 TECU in latitudinal region of 60°-75°N; then it presented THE increase towards the higher latitude and reached the value of 10 TECU near 80°N. The daytime profiles revealed TEC decrease toward high latitude in keeping with 0.8 TECU/degree. During storm the structure of latitudinal TEC profiles was essentially changed with agreement to the development of geomagnetic storm. The positive effect was observed at subauroral and auroral latitudes, negative effect was prevailed at the polar region. During the night time the ionospheric trough can be observed. In the report features of the behavior of latitudinal profiles at high-latitude ionosphere for September 2011 events were discussed.

  3. Ionospheric Plasma Drift and Structure Studies at High and Mid- Latitudes. Volume 1

    DTIC Science & Technology

    1993-12-01

    oblique ionograms measured at Goose Bay for propagation path from Argentia to Goose Bay. On this day a trough developed and moved over both stations...1993). At high latitudes the magnetospheric solar wind induced electric fields map into the ionosphere along the open and dosed field lines driving the...and Winter velocities for these high latitude stations has not been investigated. The seasonal variation at first suggests that neutral winds may be

  4. Far-ultraviolet studies. VII - The spectrum and latitude dependence of the local interstellar radiation field

    NASA Technical Reports Server (NTRS)

    Henry, R. C.; Anderson, R. C.; Fastie, W. G.

    1980-01-01

    A direct measurement has been made of the spectrum (1180-1680 A) and Gould-latitude dependence of the local interstellar radiation field, over about one-third of the sky. The result is corrected to give expected values for the entire sky. The average local 1180-1680 A energy density is 5.8 x 10 to the -17th ergs/cu cm A. The surface brightness falls off toward high latitudes much more steeply than published models predict.

  5. Variational electric fields at low latitudes and their relation to spread-F and plasma irregularities

    NASA Technical Reports Server (NTRS)

    Holtet, J. A.; Maynard, N. C.; Heppner, J. P.

    1977-01-01

    In situ measurements of variational electric fields at low latitudes, taken by OGO 6 satellite instruments, are analyzed. The observations are compared with other data on F region and spread-F structures. Conformity of the electric field fluctuations with the overall picture of low-latitude irregularities is examined empirically and theoretically, and candidate processes for generation of the observed irregularities are considered. Three distinct types of irregularities are delineated and compared.

  6. Far-ultraviolet studies. VII - The spectrum and latitude dependence of the local interstellar radiation field

    NASA Technical Reports Server (NTRS)

    Henry, R. C.; Anderson, R. C.; Fastie, W. G.

    1980-01-01

    A direct measurement has been made of the spectrum (1180-1680 A) and Gould-latitude dependence of the local interstellar radiation field, over about one-third of the sky. The result is corrected to give expected values for the entire sky. The average local 1180-1680 A energy density is 5.8 x 10 to the -17th ergs/cu cm A. The surface brightness falls off toward high latitudes much more steeply than published models predict.

  7. Altitude and latitude variations in avionics SEU and atmospheric neutron flux

    SciTech Connect

    Normand, E.; Baker, T.J. )

    1993-12-01

    The direct cause of single event upsets in SRAMs at aircraft altitudes by the atmospheric neutrons has previously been documented. The variation of the in-flight SEU rate with latitude is demonstrated by new data over a wide range of geographical locations. New measurements and models of the atmospheric neutron flux are also evaluated to characterize its variation with altitude, latitude and solar activity.

  8. THE LATITUDE DISTRIBUTION OF SMALL-SCALE MAGNETIC ELEMENTS IN SOLAR CYCLE 23

    SciTech Connect

    Jin, C. L.; Wang, J. X. E-mail: wangjx@nao.cas.cn

    2012-01-20

    With the unique data set from full-disk observations provided by Michelson Doppler Imager on board the Solar and Heliospheric Observatory in the interval embodying solar cycle 23, we have found that the cyclic variations of numbers and total flux of these small-scale magnetic elements covering fluxes of (2.9-32.0) Multiplication-Sign 10{sup 18} Mx and (4.27-38.01) Multiplication-Sign 10{sup 19} Mx show anticorrelation and correlation with sunspots, respectively. In this study, the time-latitude distributions of these anticorrelated and correlated elements are analyzed. The following results are disclosed: (1) for the correlated elements, the cyclic variations of the total flux in low-latitude and middle-latitude regions show a longer duration of cyclic maximum phase than that of an active region (AR) in the corresponding latitude region; the total flux of these elements shows the accordant south-north asymmetry with that of AR; the time-latitude distribution of their number displays a similar butterfly diagram but with a latitude distribution that is twice as wide as that of sunspots. (2) For the anticorrelated elements, the time-latitude distribution of number shows a solar cycle variation different from the sunspot butterfly diagram; in each latitude, the distribution of anticorrelated elements always shows the anticorrelated variation with that of sunspots; during solar cycle 23, the average speed of the peak latitudinal migration for anticorrelated elements reaches 7.5 deg year{sup -1}, almost three times that for sunspots. These results seem to imply that the correlated elements are the debris of decayed sunspots, and the anticorrelated elements have a different source but are affected or modulated by sunspot magnetic field.

  9. Effect of diffusion-thermal processes on the high-latitude topside ionosphere

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Raitt, W. J.; Nagy, A. F.

    1978-01-01

    The extent to which diffusion-thermal heat flow affects H(+) temperatures in the high-latitude topside ionosphere is studied. Such a heat flow occurs whenever there are H(+)-O(+) relative drifts. From our study we have found that at high-latitudes, where H(+) flows up and out of the topside ionosphere, diffusion-thermal heat flow acts to reduce H(+) temperatures by 500-600 K at altitudes above about 900 km.

  10. MITHRAS: A Program of Simultaneous Radar Observations of the High-Latitude Auroral Zone.

    DTIC Science & Technology

    1982-11-01

    CHATANIKA AND MILL - STONE HILL. The vertical arrow indicates local midnight. 29 electron densities. The nighttime minima are not as well reproduced by the... Nuit de Haute Latitude," Proceedings of GRECO Conference, Grenoble, France (September 1982). Senior, C., P. Bauer, C. Taieb, and Michel Petit, "Le R61e...Alignis, Precipitations Diffuses et Electrojets dans le Secteur Nuit de Haute Latitude," C. Senior, Proceedings of GRECO Conference, Grenoble, 1982. 0"On

  11. The effect of space weather on human heart diseases in subauroral latitudes

    NASA Astrophysics Data System (ADS)

    Samsonov, S. N.; Kleimenova, N. G.; Kozyreva, O. V.; Petrova, P. G.

    2014-12-01

    In this work the relationship between emergency medical calls for myocardial infarction in Yakutsk (subauroral geomagnetic latitudes) and parameters of the space weather near maximum (1992) and minimum (1998) geomagnetic activity is studied. The comparison of the seasonal behavior of the number of calls with the simultaneous seasonal behavior of deaths from myocardial infarctions at low latitudes (Bulgaria) exhibited significant differences. Namely, in Bulgaria, the maximum and minimum of infarctions were observed in winter and in summer, respectively; in Yakutsk, several observed maximums coincided with the sharp and considerable increase in planetary geomagnetic activity. An analysis of experimental results made it possible to suppose that, in subauroral latitudes, unlike low latitudes, a major role in the increase in the number of infarctions is played by the increase in geomagnetic activity, namely, by the appearance of night magnetospheric substorms, which are also observed in subauroral latitudes in magnetically disturbed times. Substorms are always accompanied by irregular geomagnetic Pi1 pulsations with periods of 0.5-3 Hz. These pulsations can be biotropic, like stable quasi-sinusoidal geomagnetic Pc1 pulsations in middle and low latitudes.

  12. The effect of latitude on photoperiodic control of gonadal maturation, regression and molt in birds.

    PubMed

    Dawson, Alistair

    2013-09-01

    Photoperiod is the major cue used by birds to time breeding seasons and molt. However, the annual cycle in photoperiod changes with latitude. Within species, for temperate and high latitude species, gonadal maturation and breeding start earlier at lower latitudes but regression and molt both occur at similar times at different latitudes. Earlier gonadal maturation can be explained simply by the fact that considerable maturation occurs before the equinox when photoperiod is longer at lower latitudes - genetic differences between populations are not necessary to explain earlier breeding at lower latitudes. Gonadal regression is caused either by absolute photorefractoriness or, in some species with long breeding seasons, relative photorefractoriness. In either case, the timing of regression and molt cannot be explained by absolute prevailing photoperiod or rate of change in photoperiod - birds appear to be using more subtle cues from the pattern of change in photoperiod. However, there may be no difference between absolute and relative photorefractory species in how they utilise the annual cycle in photoperiod to time regression.

  13. How much does latitude modify temperature-mortality relationship in 13 eastern US cities?

    PubMed

    Xiao, Jianpeng; Peng, Ji; Zhang, Yonghui; Liu, Tao; Rutherford, Shannon; Lin, Hualiang; Qian, Zhengmin; Huang, Cunrui; Luo, Yuan; Zeng, Weilin; Chu, Cordia; Ma, Wenjun

    2015-03-01

    Although several studies have documented that latitude might be an effect modifier of the association between temperature and mortality, little is known about how much latitude modifies the temperature-mortality relationship. In this study, we examined this research question using a distributed lag non-linear model and meta-regression analysis based on data from 13 large cities of eastern US from the US National Morbidity, Mortality, and Air Pollution Study. We found that cold effects lasted about 1 month while hot effects were acute and short-term. Meta-regression analysis showed that latitude modified both the cold and hot effects with statistical significance. The cold effect decreased with the latitude increment, with -0.11 % change of mortality effect for 1° increment, while the hot effect increased with the latitude increment, with 0.18 % change of mortality effect for 1° increment. This finding indicates the importance of latitude on temperature-related mortality risk, which is helpful for city to develop localized effective adaptation strategy in the context of climate change.

  14. Amplified mid-latitude planetary waves favour particular regional weather extremes

    NASA Astrophysics Data System (ADS)

    Screen, James A.; Simmonds, Ian

    2014-08-01

    There has been an ostensibly large number of extreme weather events in the Northern Hemisphere mid-latitudes during the past decade. An open question that is critically important for scientists and policy makers is whether any such increase in weather extremes is natural or anthropogenic in origin. One mechanism proposed to explain the increased frequency of extreme weather events is the amplification of mid-latitude atmospheric planetary waves. Disproportionately large warming in the northern polar regions compared with mid-latitudes--and associated weakening of the north-south temperature gradient--may favour larger amplitude planetary waves, although observational evidence for this remains inconclusive. A better understanding of the role of planetary waves in causing mid-latitude weather extremes is essential for assessing the potential environmental and socio-economic impacts of future planetary wave changes. Here we show that months of extreme weather over mid-latitudes are commonly accompanied by significantly amplified quasi-stationary mid-tropospheric planetary waves. Conversely, months of near-average weather over mid-latitudes are often accompanied by significantly attenuated waves. Depending on geographical region, certain types of extreme weather (for example, hot, cold, wet, dry) are more strongly related to wave amplitude changes than others. The findings suggest that amplification of quasi-stationary waves preferentially increases the probabilities of heat waves in western North America and central Asia, cold outbreaks in eastern North America, droughts in central North America, Europe and central Asia, and wet spells in western Asia.

  15. Ulysses solar wind plasma observations from peak southerly latitude through perihelion and beyond

    NASA Technical Reports Server (NTRS)

    Phillips, J. L.; Bame, S. J.; Feldman, W. C.; Gosling, J. T.; Hammond, C. M.; McComas, D. J.; Goldstein, B. E.; Neugebauer, M.

    1995-01-01

    The Ulysses spacecraft trajectory includes a peak southern latitude of -80.2 deg, reached during September 1994, and perihelion in the ecliptic plane at 134 AU in March 1995. The near-perihelion mission phase features a rapid scan through solar latitude, with rates approaching one degree per day. We will present observations through mid-May 1995, when the spacecraft will be near 1.5 AU and +50 deg solar latitude. At the time of this writing, observations from the solar wind plasma experiment have been examined through -40 deg solar latitude. At that latitude Ulysses was still immersed in fast solar wind from the south polar coronal hole, with wind speeds of 700 to 800 km/s and with a variety of fine structure. Expectations for near-perihelion measurements include times of slow, dense wind characteristic of the near-equatorial heliomagnetic streamer belt. A non-zero tilt of the streamer belt would produce recurrent intervals of fast coronal hole wind and corotating interaction regions (CIRs) caused by fast wind overtaking slow wind. Forward and reverse shock waves bounding the CIRs, routinely observed at low and intermediate latitudes beyond approximately 2 AU, will likely be absent during the northward transit due to proximity to the Sun we will summarize solar wind plasma results concerning meridional gradients in fluid parameters, large-scale and fine structure, and transient events such as coronal mass ejections.

  16. How much does latitude modify temperature-mortality relationship in 13 eastern US cities?

    NASA Astrophysics Data System (ADS)

    Xiao, Jianpeng; Peng, Ji; Zhang, Yonghui; Liu, Tao; Rutherford, Shannon; Lin, Hualiang; Qian, Zhengmin; Huang, Cunrui; Luo, Yuan; Zeng, Weilin; Chu, Cordia; Ma, Wenjun

    2015-03-01

    Although several studies have documented that latitude might be an effect modifier of the association between temperature and mortality, little is known about how much latitude modifies the temperature-mortality relationship. In this study, we examined this research question using a distributed lag non-linear model and meta-regression analysis based on data from 13 large cities of eastern US from the US National Morbidity, Mortality, and Air Pollution Study. We found that cold effects lasted about 1 month while hot effects were acute and short-term. Meta-regression analysis showed that latitude modified both the cold and hot effects with statistical significance. The cold effect decreased with the latitude increment, with -0.11 % change of mortality effect for 1° increment, while the hot effect increased with the latitude increment, with 0.18 % change of mortality effect for 1° increment. This finding indicates the importance of latitude on temperature-related mortality risk, which is helpful for city to develop localized effective adaptation strategy in the context of climate change.

  17. Characteristics of the Afternoon E-region Plasma Density Irregularities in Middle Latitudes

    NASA Astrophysics Data System (ADS)

    Kwak, Y. S.; Yang, T. Y.; Kil, H.; Otsuka, Y.

    2014-12-01

    In middle latitudes, radar probing of E-region ionospheric electron density irregularities has been carried out for several decades. However, no the afternoon (i.e., from noon to pre-sunset time) E-region field-aligned irregularities (FAIs) in middle latitude have been reported yet. On the other hand, a 40.8 MHz VHF radar operated continuously since December 2009 at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South Korea has often observed the E-region FAIs in the afternoon. In this presentation, therefore, we report firstly the afternoon observations of the mid-latitude E-region FAIs made by the Daejeon radar. We present the characteristics and statistical morphology of the mid-latitude afternoon E-region FAIs based on the continuous and long-term radar observations. And also, to investigate the afternoon E-region FAIs - Sporadic E (Es) relationship, the FAIs have been also compared with Es parameters based on observations made from an ionosonde located at Icheon (37.14°N, 127.54°E, 27.7°N dip latitude), which is 100 km north of Daejeon.

  18. Water vapour variability in the high-latitude upper troposphere - Part 2: Impact of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Sioris, Christopher E.; Zou, Jason; McElroy, C. Thomas; Boone, Chris D.; Sheese, Patrick E.; Bernath, Peter F.

    2016-02-01

    The impact of volcanic eruptions on water vapour in the high-latitude upper troposphere is studied using deseasonalized time series based on observations by the Atmospheric Chemistry Experiment (ACE) water vapour sensors, namely MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and the Fourier Transform Spectrometer (ACE-FTS). The two eruptions with the greatest impact on the high-latitude upper troposphere during the time frame of this satellite-based remote sensing mission are chosen. The Puyehue-Cordón Caulle volcanic eruption in June 2011 was the most explosive in the past 24 years and is shown to be able to account for the observed (50 ± 12) % increase in water vapour in the southern high-latitude upper troposphere in July 2011 after a minor adjustment for the simultaneous influence of the Antarctic oscillation. Eyjafjallajökull erupted in the spring of 2010, increasing water vapour in the upper troposphere at northern high latitudes significantly for a period of ˜ 1 month. These findings imply that extratropical volcanic eruptions in windy environments can lead to significant perturbations to high-latitude upper tropospheric humidity mostly due to entrainment of lower tropospheric moisture by wind-blown plumes. The Puyehue-Cordón Caulle eruption must be taken into account to properly determine the magnitude of the trend in southern high-latitude upper tropospheric water vapour over the last decade.

  19. The role of the high-latitude climate variability in seasonal predictability of the boreal winter based on model forecasts

    NASA Astrophysics Data System (ADS)

    Jung, Euihyun; Jeong, Jee-hoon

    2017-04-01

    The relationship between polar and mid-latitude climate variability is important topic in recent years. Especially, effect of extreme change in polar climate, Arctic Amplification, on mid-latitude has been disputable question and actively researched. Latest studies show the relationship between polar and extra-tropical climate relationship in boreal winter by statistical and physical method. Melting of Arctic sea ice is one of important process which can affect mid-latitude climate variability. Based on previous theories, some variables over Arctic sea have relationship with mid-latitude climate is analyzed using seasonal forecast data sets from a few models. This analysis shows different characteristics of statistical relationship according to used models. Using theoretical relationship, statistically adjusted surface air temperature over Arctic sea is used to know how it affects mid-latitude climate variables. That result shows improvement of predictability over high-latitude region can induce high forecast accuracy over mid-latitude region.

  20. Observations of ionospheric convection from the Wallops SuperDARN radar at middle latitudes

    NASA Astrophysics Data System (ADS)

    Baker, J. B. H.; Greenwald, R. A.; Ruohoniemi, J. M.; Oksavik, K.; Gjerloev, J. W.; Paxton, L. J.; Hairston, M. R.

    2007-01-01

    During geomagnetic storms the ability of the Super Dual Auroral Radar Network (SuperDARN) to measure ionospheric convection becomes limited when the radars suffer from absorption and the auroral disturbance expands equatorward of the radar sites. To overcome these shortcomings, it was decided to construct a SuperDARN radar at middle latitudes on the grounds of the NASA Wallops Flight Facility. This paper presents the first comprehensive analysis of Doppler measurements from the Wallops radar, which commenced operations in May 2005. Wallops measurements are compared with the Goose Bay radar during the onset of a geomagnetic storm on 31 August 2005: Goose Bay measured the onset of geomagnetic activity at high latitude while Wallops monitored the expansion of convection to middle latitudes. Average convection patterns binned by the Kp geomagnetic index are also presented. During weak-moderate geomagnetic activity (Kp ≤ 3) the Wallops radar observes ionospheric irregularities between 50° and 60° magnetic latitude drifting westward across much of the nightside. When these measurements are incorporated into the calculation of an average SuperDARN convection pattern, the streamlines of polar cap outflow on the nightside become kinked in a manner reminiscent of the Harang discontinuity. This morphology arises quite naturally when the two-cell convection at high latitudes merges with the prevailing westward convection at middle latitudes. During increased geomagnetic activity (Kp ≥ 3), Wallops is able to measure the expansion of auroral electric fields to middle latitudes and the average SuperDARN cross-polar cap potential is increased by 25%.