RESULTS OF A DIFFERENTIAL OMEGA TEST IN THE MACKENZIE RIVER DELTA

Geophysics ◽  
1970 ◽  
Vol 35 (3) ◽  
pp. 514-520
Author(s):  
L. W. Sobczak ◽  
G. J. Taylor
Keyword(s):  
New York ◽  
Navigation System ◽  
Low Frequency ◽  
Department Of Energy ◽  
The Arctic ◽  
The North ◽  
Radio Navigation System ◽  
The Difference ◽  
Area North ◽  
North Atlantic Area

In 1969 the Gravity Division of the Observatories Branch, Department of Energy, Mines and Resources, Ottawa, in cooperation with the Research, Development, and Programming Division of the Telecommunications and Electronics Branch of the Department of Transport, undertook an evaluation of the worldwide Omega Navigation System in the Arctic for the Polar Continental Shelf Project. Omega is a long‐range, very low frequency radio navigation system. It consists of 4 (Norway, Trinidad, Hawaii, and New York) of the planned 8 transmitters and provides navigational coverage for the North Atlantic area, North America, and parts of South America (Scull, 1969 and Dick‐Peddie, 1968). These stations presently transmit two frequencies (10.2 kHz and 13.6 kHz) in a sequential pattern synchronized in phase by means of atomic clocks (Tracor, 1968 and Findlay, 1968). The Omega receiver measures the difference of phase of received signals from a pair of transmitters. This measurement defines one line of position (LOP) in a family of hyperbolic lines. Lines of positions defined by the zero phase difference are the lines of position that are numbered on an Omega chart, and the distance between two such lines is known as a lane. A position is determined by the intersection of two lines of position within known lanes.

Air and Sea Tests of the Dectra Radio-navigation System

1959 ◽  
Vol 12 (3-4) ◽  
pp. 289-307
Author(s):  
Claud Powell
Keyword(s):  
Long Range ◽  
North Atlantic ◽  
Navigation System ◽  
Data Link ◽  
Flight Tests ◽  
The North ◽  
Radio Navigation System ◽  
The North Atlantic ◽  
North Atlantic Area ◽  
Atlantic Area

The object of this paper is to summarize the results of air and sea trials that have been obtained in the first two years' operation of the experimental Dectra chain in the North Atlantic area. Reference is also made to observations at fixed monitor stations, and briefly to the Dectra data link for air-to-ground transmission of the Dectra fix.Dectra, which stands for ‘Decca Track and Range’, is a long-range position-fixing system derived from the Decca Navigator. Early in 1957 two of the three transmitting stations forming a Dectra chain designed to cover the North Atlantic air routes were put into operation and flight tests began in March of that year; in the following October, air trials started using all three transmissions. Various tests at sea have also been carried out, although on a much less extensive scale than those in the air.

scholarly journals Empirical Mode Reduction in a Model of Extratropical Low-Frequency Variability

2006 ◽  
Vol 63 (7) ◽  
pp. 1859-1877 ◽  
Author(s):  
D. Kondrashov ◽  
S. Kravtsov ◽  
M. Ghil
Keyword(s):  
Numerical Study ◽  
Singular Spectrum Analysis ◽  
Low Frequency ◽  
The Arctic ◽  
Reduced Model ◽  
The North ◽  
Low Frequency Variability ◽  
Intraseasonal Oscillations ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

Abstract This paper constructs and analyzes a reduced nonlinear stochastic model of extratropical low-frequency variability. To do so, it applies multilevel quadratic regression to the output of a long simulation of a global baroclinic, quasigeostrophic, three-level (QG3) model with topography; the model's phase space has a dimension of O(104). The reduced model has 45 variables and captures well the non-Gaussian features of the QG3 model's probability density function (PDF). In particular, the reduced model's PDF shares with the QG3 model its four anomalously persistent flow patterns, which correspond to opposite phases of the Arctic Oscillation and the North Atlantic Oscillation, as well as the Markov chain of transitions between these regimes. In addition, multichannel singular spectrum analysis identifies intraseasonal oscillations with a period of 35–37 days and of 20 days in the data generated by both the QG3 model and its low-dimensional analog. An analytical and numerical study of the reduced model starts with the fixed points and oscillatory eigenmodes of the model's deterministic part and uses systematically an increasing noise parameter to connect these with the behavior of the full, stochastically forced model version. The results of this study point to the origin of the QG3 model's multiple regimes and intraseasonal oscillations and identify the connections between the two types of behavior.

High-frequency seismic noise as a function of depth

1991 ◽  
Vol 81 (4) ◽  
pp. 1101-1114
Author(s):  
Jerry A. Carter ◽  
Noel Barstow ◽  
Paul W. Pomeroy ◽  
Eric P. Chael ◽  
Patrick J. Leahy
Keyword(s):  
New York ◽  
High Frequency ◽  
Seismic Noise ◽  
Low Frequency ◽  
Time Variability ◽  
Orthogonal Components ◽  
The Difference ◽  
Frequency Coherence ◽  
Cultural Noise ◽  
Natural Wind

Abstract Evidence is presented supporting the view that high-frequency seismic noise decreases with increased depth. Noise amplitudes are higher near the free surface where surface-wave noise, cultural noise, and natural (wind-induced) noise predominate. Data were gathered at a hard-rock site in the northwestern Adirondack lowlands of northern New York. Between 15- and 40-Hz noise levels at this site are more than 10 dB less at 945-m depth than they are at the surface, and from 40 to 100 Hz the difference is more than 20 dB. In addition, time variability of the spectra is shown to be greater at the surface than at either 335- or 945-m depths. Part of the difference between the surface and subsurface noise variability may be related to wind-induced noise. Coherency measurements between orthogonal components of motion show high-frequency seismic noise is more highly organized at the surface than it is at depth. Coherency measurements between the same component of motion at different vertical offsets show a strong low-frequency coherence at least up to 945-m vertical offsets. As the vertical offset decreases, the frequency band of high coherence increases.

scholarly journals XVII. Contributions to terrestrial magnetism. — No. VII

1846 ◽  
Vol 136 ◽  
pp. 237-336 ◽  
Keyword(s):  
New York ◽  
Magnetic Force ◽  
The Arctic ◽  
General View ◽  
Magnetic Survey ◽  
Terrestrial Magnetism ◽  
North American Continent ◽  
The North ◽  
Common Unit ◽  
The Moment

Containing a Magnetic Survey of a considerable portion of the North American Continent. From the moment that the fact was known, that the locality of the maximum of the magnetic Force in a hemisphere is not coincident, as was previously supposed, with the locality where the dip of the needle is 90°, researches in terrestrial magnetism assumed an interest and importance greatly exceeding that which they before pos­sessed; for it was obvious that the hypothesis which then generally prevailed regard­ing the distribution of the magnetic Force at the surface of the globe, and which had been based on a too-limited induction, was erroneous, and that even the broad out­ line of the general view of terrestrial magnetism had to be recast. The observations on which this discovery rested, (being those which I had had an opportunity of making in 1818, 1819 and 1820 within the Arctic Circle, and at New York in 1822,) were published in 1825*; they constituted, I may be permitted to say, an important feature in the views, which led the British Association in the year 1835 to request that a report should be prepared, in which the state of our knowledge in respect to the variations of the magnetic Force at different parts of the earth’s sur­face should be reviewed, and, as is customary in the reports presented to that very useful institution, that those measures should be pointed out which appeared most desirable for the advancement of this branch of science. In the maps attached to the report, the isodynamic lines on the surface of the globe were drawn simply in conformity with observations, and unmixed with hypothesis of any sort. The obser­vations collected for that purpose were not those of any particular individual or of any single nation, but embodied the results obtained by all persons who up to that period had taken part in such researches, subjected to such amount of discussion only as conveyed a knowledge of the modes of observation severally employed, and reduced the whole to a common unit.

scholarly journals The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

2018 ◽  
Vol 18 (2) ◽  
pp. 555-570 ◽  
Author(s):  
Jessie M. Creamean ◽  
Maximilian Maahn ◽  
Gijs de Boer ◽  
Allison McComiskey ◽  
Arthur J. Sedlacek ◽  
...  
Keyword(s):  
Cloud Microphysics ◽  
Department Of Energy ◽  
The Arctic ◽  
North Slope ◽  
The North ◽  
The Us ◽  
Range Transport ◽  
North Slope Of Alaska ◽  
Atmospheric Radiation Measurement ◽  
Arctic Atmosphere

Abstract. The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

The Evaluation and Use of the Dectra Navigation System

1958 ◽  
Vol 11 (4) ◽  
pp. 377-384
Author(s):  
E. W. Hare
Keyword(s):  
Long Range ◽  
North Atlantic ◽  
Navigation System ◽  
Radio Navigation ◽  
The North ◽  
Radio Navigation System ◽  
Accurate Position ◽  
The North Atlantic

Dectra is a long-range radio navigation system designed to give accurate position fixing coverage over specific areas, and in particular over long trans-oceanic crossings. The position of an aircraft or ship equipped with a Dectra receiver is continuously available in the form of dial indications relating to coordinates of a Dectra lattice, and in addition this information can be presented pictorially on a normal Decca flight log. The system is at present functioning over the North Atlantic, and flight trials have been in progress since May 1957. This paper discusses the experience gained and the results obtained in the trials.

Arctic Flights

1928 ◽  
Vol 32 (214) ◽  
pp. 885-900
Author(s):  
G. H. Wilkins
Keyword(s):  
New York ◽  
Full Advantage ◽  
San Francisco ◽  
New Guinea ◽  
Great Circle ◽  
North Pole ◽  
The Arctic ◽  
The North ◽  
The Way

When Trans-Arctic transportation becomes common, when air routes take full advantage of great circle courses, when we travel from New York to New Guinea via Point Barrow, Alaska, from Chicago to China almost hitting the North Pole on the way, and from San Francisco to Moscow via Spitsbergen, then, and then only, will those concerned with aerial transportation realise the facilities the Arctic affords the aerial navigator.

scholarly journals Coverage of the Arctic Development in Russian Mass Media Discourse (by the example of Rossiyskaya Gazeta)

2019 ◽  
Vol 8 (4) ◽  
pp. 735-746
Author(s):  
Natalia Avdonina ◽  
Svetlana Dolgoborodova
Keyword(s):  
National Development ◽  
Low Frequency ◽  
The Arctic ◽  
Media Discourse ◽  
Second Stage ◽  
The North ◽  
Official Position ◽  
The Russian Federation ◽  
Two Stages ◽  
Specific Reason

The trends in the official Russian arctic media discourse reflect a sustainable public interest to the issues of the Arctic national development, as well as to the geo-political situation and Russia’s military buildup in the North. The article analyzes the trends in the coverage of Arctic-related issues in the official Russian discourse by the example of “Rossiyskaya Gazeta” — the official print newspaper of RF government. The study covers the period of 2001–2018, which is characterized by topicality of arctic discourse. The dynamics of the discourse can be visibly divided into two stages. The first stage started in 2001 and finished in 2007 with the Russian expedition “Arctic-2007”, which planted the flag of the Russian Federation on the bottom of the Arctic Ocean. The discourse of the stage features low frequency of publications on the topic and neutral emotional text sentiment. The discourse of the second stage (2008–2018) exhibits a noticeably wider topical range of publications on Arctic-related issues, as well as their reactionary and agonic spirit. The analysis resulted in an inference that the publications on Arctic-related problems in the newspaper reflect the official position of RF authorities, and have a specific-reason character.

scholarly journals Contributions from intrinsic low-frequency climate variability to the accelerated decline in Arctic sea ice in recent decades

2018 ◽  
Author(s):  
Lejiang Yu ◽  
Shiyuan Zhong
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Low Frequency ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Self Organizing Maps ◽  
The North ◽  
Arctic Sea ◽  
Atmospheric Circulation Anomalies

Abstract. In recent decades, the Arctic sea ice has been declining at a rapid pace as the Arctic is warmed at a rate of twice the global average. The underlying physical mechanisms for the Arctic warming and accelerated sea ice retreat are not fully understood. In this study, we apply a relatively novel statistical method called Self-Organizing Maps (SOM) to examine the trend and variability of autumn Arctic sea ice in the past four decades and their relationships to large-scale atmospheric circulation changes. Our results show a large portion of the autumn Arctic sea ice decline between 1979 and 2016 may be associated with anomalous autumn Arctic intrinsic atmospheric modes. The Arctic atmospheric circulation anomalies associated with anomalous sea surface temperature patterns over the North Pacific and North Atlantic influence Arctic sea ice primarily through anomalous temperature and water vapor advection and associated radiative feedback.

scholarly journals The influence of local oil exploration, regional wildfires, and long range transport on summer 2015 aerosol over the North Slope of Alaska

2017 ◽  
Author(s):  
Jessie M. Creamean ◽  
Maximilian Maahn ◽  
Gijs de Boer ◽  
Allison McComiskey ◽  
Arthur J. Sedlacek ◽  
...  
Keyword(s):  
Long Range ◽  
Cloud Microphysics ◽  
Department Of Energy ◽  
The Arctic ◽  
North Slope ◽  
Long Range Transport ◽  
The North ◽  
Range Transport ◽  
North Slope Of Alaska ◽  
Arctic Atmosphere

Abstract. The Arctic is warming at an alarming rate, yet the processes that contribute to enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly-changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015’s central Alaskan wildfires, and to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

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