A MODEL OF GEOMAGNETIC MICROPULSATIONS WITH LONG PERIODS

1964 ◽  
Vol 42 (1) ◽  
pp. 200-207 ◽  
Author(s):  
J. A. Jacobs ◽  
T. Watanabe
Keyword(s):  
Radio Wave ◽  
Solar Eclipse ◽  
Phase Relationship ◽  
Observational Evidence ◽  
Magnetic Line ◽  
Ionospheric Currents ◽  
The North ◽  
Low Latitudes ◽  
Stable Frequency ◽  
Eclipse Effect

A physical process whereby a hydromagnetic oscillation of a magnetic line of force passing through the auroral zones gives rise to a system of ionospheric currents is described in this paper. Geomagnetic micropulsations, at least in middle and low latitudes, are claimed to be due to ionospheric currents thus produced. Observational evidence in support of this viewpoint for micropulsations in the daylight hemisphere is provided by the solar eclipse effect that the intensity of micropulsations is weakened in the eclipsed zone. The phase relationship between micropulsations in the north–south component and oscillations in the received frequency of a radio wave which is emitted from a station with a stable frequency of the order of several to tens of megacycles, and is propagated through the ionosphere, is correctly interpreted by the above theory.

scholarly journals A captorhinid-dominated assemblage from the palaeoequatorial Permian of Menorca (Balearic Islands, western Mediterranean)

2021 ◽  
pp. 1-21
Author(s):  
Rafel MATAMALES-ANDREU ◽  
Francesc X. ROIG-MUNAR ◽  
Oriol OMS ◽  
Àngel GALOBART ◽  
Josep FORTUNY
Keyword(s):  
Western Mediterranean ◽  
Balearic Islands ◽  
Distribution Area ◽  
Lower Permian ◽  
Incertae Sedis ◽  
The North ◽  
Low Latitudes ◽  
High Fibre ◽  
Successful Group ◽  
Neighbouring Island

ABSTRACT Moradisaurine captorhinid eureptiles were a successful group of high-fibre herbivores that lived in the arid low latitudes of Pangaea during the Permian. Here we describe a palaeoassemblage from the Permian of Menorca (Balearic Islands, western Mediterranean), consisting of ichnites of small captorhinomorph eureptiles, probably moradisaurines (Hyloidichnus), and parareptiles (cf. Erpetopus), and bones of two different taxa of moradisaurines. The smallest of the two is not diagnostic beyond Moradisaurinae incertae sedis. The largest one, on the other hand, shows characters that are not present in any other known species of moradisaurine (densely ornamented maxillar teeth), and it is therefore described as Balearosaurus bombardensis gen. et sp. nov. Other remains found in the same outcrop are identified as cf. Balearosaurus bombardensis gen. et sp. nov., as they could also belong to the newly described taxon. This species is sister to the moradisaurine from the lower Permian of the neighbouring island of Mallorca, and is also closely related to the North American genus Rothianiscus. This makes it possible to suggest the hypothesis that the Variscan mountains, which separated North America from southern Europe during the Permian, were not a very important palaeobiogeographical barrier to the dispersion of moradisaurines. In fact, mapping all moradisaurine occurrences known so far, it is shown that their distribution area encompassed both sides of the Variscan mountains, essentially being restricted to the arid belt of palaeoequatorial Pangaea, where they probably outcompeted other herbivorous clades until they died out in the late Permian.

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

scholarly journals I. Report of the observations of the total solar eclipse of August 29, 1886, made at Carriacou

1887 ◽  
Vol 42 (251-257) ◽  
pp. 316-318
Keyword(s):  
Solar Eclipse ◽  
West Indies ◽  
Royal Society ◽  
Total Solar Eclipse ◽  
Small Island ◽  
Small Islands ◽  
The West ◽  
The North

Carriacou is a small island situated about twenty miles to the north of the island of Grenada, the chief of the Windward group, and furnished an excellent site for the observation of the last solar eclipse. Most of the observers sent by the Eclipse Committee of the Royal Society to the West Indies in August of last year remained at Grenada, or on the small islands in its immediate vicinity, whilst Mr. Maunder and myself occupied the more distant northern station, where the totality was slightly diminished in duration. The work proposed for Mr. Maunder was to secure a series of photographs of the corona, with exposures of 40s. and under, and also to obtain two photographs of the spectrum of the corona with the longest exposures possible.

scholarly journals Phase effects in subionospheric VLF/LF signals observed at middle and low latitudes during the August 21, 2017 total solar eclipse

2019 ◽  
Author(s):  
Viktor Fedun ◽  
Alexandr Rozhnoi ◽  
Mariya Solovieva ◽  
Dimitar Ouzounov ◽  
Peter Gallagher ◽  
...  
Keyword(s):  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Low Latitudes

Solar Eclipse Effect on Shelter Air Temperature

1996 ◽  
Vol 77 (1) ◽  
pp. 89-99 ◽  
Author(s):  
M. Segal ◽  
R. W. Turner ◽  
J. Prusa ◽  
R. J. Bitzer ◽  
S. V. Finley
Keyword(s):  
Air Temperature ◽  
Solar Eclipse ◽  
Eclipse Effect

Methods and Applications of Cenozoic Marine Diatom Biostratigraphy

2007 ◽  
Vol 13 ◽  
pp. 61-83 ◽  
Author(s):  
Reed P. Scherer ◽  
Andrey Yu. Gladenkov ◽  
John A. Barron
Keyword(s):  
North Pacific ◽  
Marine Diatom ◽  
Diatom Assemblages ◽  
Ocean Drilling ◽  
The North ◽  
Planktonic Diatom ◽  
Low Latitudes ◽  
The Antarctic ◽  
The North Pacific ◽  
Early Paleogene

Diatoms provide the chief Cenozoic biostratigraphic tool in marine sediments beneath high primary productivity zones, especially where calcareous fossils are rare or poorly preserved. Diatom biostratigraphy, which is based on originations and extinctions of unique taxa, is especially useful in circum-Antarctic, equatorial Pacific, and high latitude North Pacific marine successions, which are available largely from ocean drilling. Oligocene to Holocene diatom biostratigraphic zonations are correlated with the geopaleomagnetic timescale, resulting in age control of million-year to as little as hundred-thousand year resolution. Paleocene and Eocene zonations are less well developed and have lower chronostratigraphic control, but are more widely applicable, because planktonic diatom assemblages of the globally warm early Paleogene were less provincial. We review the principals and methods of biostratigraphy and the application of diatoms to age control in stratigraphic successions worldwide. Distinct biostratigraphic zonations defined for the low latitudes, the North Pacific and the Antarctic, are reviewed, and Atlantic records and Antarctic coastal records are discussed. New biostratigraphic tools are introduced, including multidimensional graphic correlation of published diatom ranges.

scholarly journals Phase relationships between Antarctic and Greenland climate records

2002 ◽  
Vol 35 ◽  
pp. 451-456 ◽  
Author(s):  
Eric J. Steig ◽  
Richard B. Alley
Keyword(s):  
Southern Hemisphere ◽  
Climate Models ◽  
Phase Relationship ◽  
Ice Cores ◽  
Phase Lag ◽  
The North ◽  
Climate Records ◽  
Climate Time Series ◽  
Different Characteristics ◽  
Phase Relationships

AbstractComparison of climate records from Antarctic and Greenland ice cores shows that the two regions respond asynchronously during millennial-scale climate changes. the apparent out-of-phase relationship between the records has been described as a climate ``seesaw’’ in which cooling in the Northern Hemisphere is balanced by warming in the Southern Hemisphere. the same relationship has also been attributed to the initiation of climate-change events in the Southern Hemisphere, rather than the North Atlantic as is conventionally assumed. A simple statistical approach−band-pass filtering combined with lag–correlation tests−used to examine the phase relationships in more detail shows that neither an anti-phase nor a phase-lag relationship adequately describes the observations. Whereas Antarctic and Greenland climate records do exhibit approximate anti-phase behavior about 50% of the time, they are generally in phase during cooling. A phase lead of Southern Hemisphere climate of 1000–1600 years is statistically indistinguishable from a lag of 400–800 years, whether for Dansgaard–Oeschger, Heinrich or longer-duration events. the ``seesaw’’ or ``Southern lead’’ appearance of the data arises from the fundamentally different characteristics of the climate time series, most importantly the absence of rapid warming events in Antarctica comparable to those in Greenland. to be consistent with the observations, climate models will need to capture these characteristics, in addition to reproducing the correct phase relationships.

scholarly journals Total solar eclipse, 1905, August 29-30. Preliminary report of the observations made at Guelma, Algeria

1906 ◽  
Vol 77 (514) ◽  
pp. 56-76
Keyword(s):  
Solar Eclipse ◽  
Royal Society ◽  
Preliminary Report ◽  
Total Solar Eclipse ◽  
The South ◽  
Royal Astronomical Society ◽  
The North ◽  
Royal Observatory ◽  
The Government ◽  
Government Grant

The expedition to which this report refers was one of those organised by the Joint Permanent Eclipse Committee of the Royal Society and the Royal Astronomical Society; it was supported by a grant made by the Government Grant Committee. Guelma was chosen for the site of the observations, as being an inland station between Sfax, which was selected for an expedition from the Royal Observatory, Greenwich, and Philippeville, which it was at first expected Sir Norman Lockyer would occupy. Guelma is 58 kilometres from Bona, 65 kilometres from Philippeville, 55 kilometres from the nearest coast of the Mediterranean Sea; it lies at a height of about 1200 feet above sea-level on the south side of the Valley of the Seybouze, amongst hills which range in height from about 3100 feet at 13 kilometres to the north, to about 4700 feet at 11 kilometres on the south, where lies the celebrated mountain, Mahouna, “the sleeping lady,” so called from the resemblance of its silhouette to the form of a woman. (For the position of the observing hut, see p. 59.)

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