scholarly journals Diurnal and annual variations of meteor rates at the Arctic circle

2004 ◽  
Vol 4 (1) ◽  
pp. 1-20 ◽  
Author(s):  
W. Singer ◽  
J. Weiß ◽  
U. von Zahn
Keyword(s):  
Diurnal Variations ◽  
The Arctic ◽  
Noctilucent Cloud ◽  
Arctic Circle ◽  
Annual Cycles ◽  
Annual Variations ◽  
The North ◽  
Radar Antenna ◽  
Metal Layers ◽  
Antenna Field

Abstract. Meteors are an important source for (a) the metal atoms of the upper atmosphere metal layers and (b) for condensation nuclei, the existence of which are a prerequisite for the formation of noctilucent cloud particles in the polar mesopause region. For a better understanding of these phenomena, it would be helpful to know accurately the annual and diurnal variations of meteor rates. So far, these rates have been little studied at polar latitudes. Therefore we have used the 33 MHz meteor radar of the ALOMAR observatory at 69° N to measure the meteor rates at this location for two full annual cycles. This site, being within 3° of the Arctic circle, offers in addition an interesting capability: The axis of its antenna field points (almost) towards the North ecliptic pole once each day of the year. In this particular viewing direction, the radar monitors the meteoroid influx from (almost) the entire ecliptic Northern hemisphere. We report on the observed diurnal variations (averaged over one month) of meteor rates and their significant alterations throughout the year. The ratio of maximum over minimum meteor rates throughout one diurnal cycle is in January and February about 5, from April through December 2.3±0.3. If compared with similar measurements at mid-latitudes, our expectation, that the amplitude of the diurnal variation is to decrease towards the North pole, is not really borne out. Observations with the antenna axis pointing towards the North ecliptic pole showed that the rate of deposition of meteoric dust is substantially larger during the Arctic NLC season than the annual mean deposition rate. The daylight meteor showers of the Arietids, Zeta Perseids, and Beta Taurids supposedly contribute considerably to the June maximum of meteor rates. We note, though, that with the radar antenna pointing as described above, all three meteor radiants are close to the local horizon. This radiant location should cause most of these shower meteors to occur above 100 km altitude. In our observations, the June maximum in meteor rate is produced, however, almost exclusively by meteors below 100 km altitude.

scholarly journals Diurnal and annual variations of meteor rates at the arctic circle

2004 ◽  
Vol 4 (5) ◽  
pp. 1355-1363 ◽  
Author(s):  
W. Singer ◽  
U. von Zahn ◽  
J. Weiß
Keyword(s):  
Diurnal Variations ◽  
The Arctic ◽  
Noctilucent Cloud ◽  
Arctic Circle ◽  
Annual Cycles ◽  
Annual Variations ◽  
The North ◽  
Radar Antenna ◽  
Metal Layers ◽  
Antenna Field

Abstract. Meteors are an important source for (a) the metal atoms of the upper atmosphere metal layers and (b) for condensation nuclei, the existence of which are a prerequisite for the formation of noctilucent cloud particles in the polar mesopause region. For a better understanding of these phenomena, it would be helpful to know accurately the annual and diurnal variations of meteor rates. So far, these rates have been little studied at polar latitudes. Therefore we have used the 33 MHz meteor radar of the ALOMAR observatory at 69° N to measure the meteor rates at this location for two full annual cycles. This site, being within 3° of the Arctic circle, offers in addition an interesting capability: The axis of its antenna field points (almost) towards the North ecliptic pole once each day of the year. In this particular viewing direction, the radar monitors the meteoroid influx from (almost) the entire ecliptic Northern hemisphere. We report on the observed diurnal variations (averaged over one month) of meteor rates and their significant alterations throughout the year. The ratio of maximum over minimum meteor rates throughout one diurnal cycle is in January and February about 5, from April through December 2.3±0.3. If compared with similar measurements at mid-latitudes, our expectation, that the amplitude of the diurnal variation is to decrease towards the North pole, is not really borne out. Observations with the antenna axis pointing towards the North ecliptic pole showed that the rate of deposition of meteoric dust is substantially larger during the Arctic NLC season than the annual mean deposition rate. The daylight meteor showers of the Arietids, Zeta Perseids, and Beta Taurids supposedly contribute considerably to the June maximum of meteor rates. We note, though, that with the radar antenna pointing as described above, all three meteor radiants are close to the local horizon but all three radiants were detected.

Northward ho! Obama, Diefenbaker and the North American Arctic

Polar Record ◽  
2015 ◽  
Vol 52 (2) ◽  
pp. 252-255
Author(s):  
Klaus J. Dodds
Keyword(s):  
Native American ◽  
Aleutian Islands ◽  
The Arctic ◽  
Arctic Circle ◽  
The North ◽  
American President ◽  
North American Arctic ◽  
To Come ◽  
Franklin Delano Roosevelt ◽  
Lying Down

President Barrack Obama became, in September 2015, the first US president to travel north of the Arctic Circle. Having started his Alaskan itinerary in Anchorage, attending and speaking at a conference involving Secretary of State John Kerry and invited guests, the president travelled north to the small town of Kotzebue, a community of some 3000 people with the majority of inhabitants identifying as native American. Delivered to an audience in the local high school numbering around 1000, the 41st US president placed his visit within a longer presidential tradition of northern visitation: I did have my team look into what other Presidents have done when they visited Alaska. I’m not the first President to come to Alaska.Warren Harding spent more than two weeks here – which I would love to do. But I can't leave Congress alone that long. (Laughter.) Something might happen. When FDR visited – Franklin Delano Roosevelt – his opponents started a rumor that he left his dog, Fala, on the Aleutian Islands – and spent 20 million taxpayer dollars to send a destroyer to pick him up. Now, I’m astonished that anybody would make something up about a President. (Laughter.) But FDR did not take it lying down. He said, “I don't resent attacks, and my family doesn't resent attacks – but Fala does resent attacks. He's not been the same dog since.” (Laughter.) President Carter did some fishing when he visited. And I wouldn't mind coming back to Alaska to do some fly-fishing someday. You cannot see Alaska in three days. It's too big. It's too vast. It's too diverse. (Applause.) So I’m going to have to come back. I may not be President anymore, but hopefully I’d still get a pretty good reception. (Applause.) And just in case, I’ll bring Michelle, who I know will get a good reception. (Applause.) . . .. But there's one thing no American President has done before – and that's travel above the Arctic Circle. (Applause.) So I couldn't be prouder to be the first, and to spend some time with all of you (Obama 2015a).

Shrines and Sovereigns: Life, Death, and Religion in Rural Azerbaijan

2011 ◽  
Vol 53 (3) ◽  
pp. 654-681 ◽  
Author(s):  
Bruce Grant
Keyword(s):  
Twentieth Century ◽  
Open Field ◽  
Religious Tradition ◽  
Full Scale ◽  
The Arctic ◽  
The West ◽  
Arctic Circle ◽  
Rapid Succession ◽  
The North ◽  
Land Mass

Shrines fill the Eurasian land mass. They can be found from Turkey in the west to China in the east, from the Arctic Circle in the north to Afghanistan in the south. Between town and country, they can consist of full-scale architectural complexes, or they may compose no more than an open field, a pile of stones, a tree, or a small mausoleum. They have been at the centers and peripheries of almost every major religious tradition of the region: Zoroastrianism, Judaism, Christianity, Islam, and Buddhism. Yet in the formerly socialist world, these places of pilgrimage have something even more in common: they were often cast as the last bastions of religious observance when churches, mosques, temples, and synagogues were sent crashing to the ground in rapid succession across the twentieth century.

scholarly journals Forward to the north: two Euro-Mediterranean bumblebee species now cross the Arctic Circle

2015 ◽  
Vol 51 (4) ◽  
pp. 303-309 ◽  
Author(s):  
Baptiste Martinet ◽  
Pierre Rasmont ◽  
Björn Cederberg ◽  
Dimitri Evrard ◽  
Frode Ødegaard ◽  
...  
Keyword(s):  
The Arctic ◽  
Arctic Circle ◽  
Bumblebee Species ◽  
The North

scholarly journals Metagenome-assembled genomes of phytoplankton communities across the Arctic Circle

2020 ◽  
Author(s):  
A. Duncan ◽  
K. Barry ◽  
C. Daum ◽  
E. Eloe-Fadrosh ◽  
S. Roux ◽  
...  
Keyword(s):  
Environmental Dna ◽  
The Arctic ◽  
Protein Families ◽  
Genomic Context ◽  
Arctic Circle ◽  
Surface Ocean ◽  
The North ◽  
Phytoplankton Communities ◽  
Metagenome Sequencing ◽  
Plankton Diversity

AbstractPhytoplankton communities significantly contribute to global biogeochemical cycles of elements and underpin marine food webs. Although their uncultured genetic diversity has been estimated by planetary-scale metagenome sequencing and subsequent reconstruction of metagenome-assembled genomes (MAGs), this approach has yet to be applied for eukaryote-enriched polar and non-polar phytoplankton communities. Here, we have assembled draft prokaryotic and eukaryotic MAGs from environmental DNA extracted from chlorophyll a maximum layers in the surface ocean across the Arctic Circle in the Atlantic. From 679 Gbp and estimated 50 million genes in total, we recovered 140 MAGs of medium to high quality. Although there was a strict demarcation between polar and non-polar MAGs, adjacent sampling stations in each environment on either side of the Arctic Circle had MAGs in common. Furthermore, phylogenetic placement revealed eukaryotic MAGs to be more diverse in the Arctic whereas prokaryotic MAGs were more diverse in the Atlantic south of the Arctic Circle. Approximately 60% of protein families were shared between polar and non-polar MAGs for both prokaryotes and eukaryotes. However, eukaryotic MAGs had more protein families unique to the Arctic whereas prokaryotic MAGs had more families unique to south of the Arctic circle. Thus, our study enabled us to place differences in functional plankton diversity in a genomic context to reveal that the evolution of these MAGs likely was driven by significant differences in the seascape on either side of an ecosystem boundary that separates polar from non-polar surface ocean waters in the North Atlantic.

scholarly journals Henrietta Kent and the Feminised North

Nordlit ◽  
2007 ◽  
Vol 11 (2) ◽  
pp. 71 ◽  
Author(s):  
Heidi Hansson
Keyword(s):  
Public Interest ◽  
The Arctic ◽  
Cultural Activity ◽  
Narrative Self ◽  
Arctic Circle ◽  
The North ◽  
The Times

Some time around 1876, S. H. Kent, Susanna Sarah Henrietta Kent or Henrietta Kent as she probably called herself, travelled through the northern parts of Norway and Sweden with her elderly mother. Her impressions from the northern trip were published in two volumes entitled Within the Arctic Circle: Experiences of Travel through Norway, to the North Cape, Sweden and Lapland, advertised in The Times 6 February 1877. There was a great deal of public interest in the Arctic at the time due to the scientific and cultural activity leading up to the firstInternational Polar Year 1882-83. Kent, however, does not foreground the adventure and excitement associated with the Polar expeditions in her narrative. Instead, she concentrates on the kind people and pleasant aspects of northern Scandinavia, asserting that the difficultiesof northern travel have been exaggerated and that nothing should "deter even lady travellers" from going North. At least as she presents the exercise in her preface, travelling in Norway and Sweden requires no particular strength or stamina. The dangers of the wild as well as the romance of the Arctic are absent from her book, makingnorthern Scandinavia seem quite woman-friendly. Kent's travelogue demonstrates in many ways the interaction between the construction of a gendered narrative self and the gendering of place.

The Arctic Circle: Aspects of the North from Circumpolar Nations

1976 ◽  
Vol 8 (4) ◽  
pp. 411
Author(s):  
John D. Jacobs ◽  
William C. Wonders
Keyword(s):  
The Arctic ◽  
Arctic Circle ◽  
The North

The intensity of the accumulation of residual deformations in the railway track operated in complex natural and climatic conditions

2020 ◽  
pp. 24-34
Author(s):  
L. S. Blazhko ◽  
◽  
E. V. Chernyaev ◽  
V. A. Chernyaeva ◽  
V. V. Ganchits ◽  
...  
Keyword(s):  
Practical Importance ◽  
Strength Properties ◽  
Climatic Conditions ◽  
Railway Track ◽  
The Arctic ◽  
Track Structure ◽  
Arctic Circle ◽  
Railway Line ◽  
The North ◽  
Residual Deformations

Objective: To analyze the results of observations conducted to assess the intensity of the accumulation of residual deformations in the railway track structure operated in severe natural and climatic conditions (the observation site is located above the Arctic Circle). The following were also taken into account: the railway track design (type of intermediate fasteners, track slab, condition of the ballast bed), the railway line scheme, the tonnage handled, the train speed and the axle load. Methods: Mathematical statistics, data processing. Results: The dependences of the railway track deformation and strength properties, including the tonnage handled, have been obtained. Practical importance: The presented observation results of the assessment of the intensity of deformation accumulation in the railway track structure operated in the severe natural and climatic conditions of the North of the Arctic Circle indicate that the use of increased axle load wagons will entail a significant reduction in overhaul life and an increase in the track maintenance operating expenditures

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