THE POLARIZATION CHARACTERISTICS OF Pi-2 MICROPULSATIONS AND THEIR RELATION TO THE DETERMINATION OF POSSIBLE SOURCE MECHANISMS FOR THE PRODUCTION OF NIGHTTIME IMPULSIVE MICROPULSATION ACTIVITY

1967 ◽  
Vol 45 (3) ◽  
pp. 1319-1335 ◽  
Author(s):  
Gordon Rostoker
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Horizontal Plane ◽  
Auroral Zone ◽  
Propagation Path ◽  
Source Mechanisms ◽  
Polarization Characteristics ◽  
Direction Of Polarization

From the analysis of 20 separate events it is shown that Pi-2 micropulsations are polarized in an anticlockwise sense in the horizontal plane at northern-hemisphere mid-latitude stations. Combined with the knowledge that in the southern hemisphere polarization is predominantly in the clockwise sense, it can be inferred that at least the last part of the propagation path of the Pi 2 from the auroral zone to the observing station is traversed in the Alfvén mode. The presence of occasional pulsations possessing clockwise polarization in the northern hemisphere and anticlockwise polarization in the southern hemisphere suggests that the Alfvén mode alone is insufficient to explain the mode of propagation of a Pi 2. It is shown how ionospheric screening may influence the direction of polarization of a micropulsation. It is found that the initial kick of a Pi-2 micropulsation is strongly related to the sign of the accompanying geomagnetic bay. Deviations from this trend are discussed and it is shown that the Pi-2 micropulsation train and the initial kick may be considered as two separate effects. A theory for the origin of Pi-2 micropulsations is proposed.

scholarly journals 24. Commission Des Parallaxes Stellaires Et Des Mouvements Propres

1950 ◽  
Vol 7 ◽  
pp. 260-266 ◽  
Author(s):  
M. J. Jackson
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere

The determination of stellar parallaxes photographically using occulting shutters initiated by Schlesinger at Yerkes in 1903 and taken up vigorously at a number of observatories in the northern hemisphere about 1913 and in the southern hemisphere about 1925 has resulted in the determination of more than 9000 parallaxes relating to more than 5000 stars.The position at the end of 1947 compared with that at the end of 1934 (as shown in I.A.U. Transactions, Vol. 5, 149) is approximately as follows, although for want of official figures some of the data are only estimates.

scholarly journals Observational description of the warp in our galaxy

1979 ◽  
Vol 84 ◽  
pp. 493-499 ◽  
Author(s):  
A. P. Henderson
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Outer Region ◽  
Neutral Hydrogen ◽  
Reduction Stage ◽  
University Of Maryland ◽  
The Galaxy ◽  
Region 10 ◽  
The University

In 1975 F. J. Kerr and P. F. Bowers of the University of Maryland made a full coverage survey of the neutral hydrogen in the southern hemisphere between ±10° latitude from 240° to 350° in longitude. This survey taken with the CSIRO 18 meter telescope is still in the reduction stage but when completed it will provide an ideal complement to the full ±10° coverage of the northern sky by H. Weaver and D. R. W. Williams (1973). The possibility of a unified analysis of the outer region of the Galaxy has inspired this present study. The plan here is to use the ±10° Weaver-Williams survey in the region 10° < ℓ < 130°; the ±30° extension to this survey (H. Weaver and D. R. W. Williams, 1974) in the region 115° < ℓ < 245° and finally the Kerr-Bowers survey, 240° < ℓ < 350°. Since the latter survey is incompletely reduced at this time we have only used profiles at 5° intervals in longitude and thereby have produced a preliminary determination of the plane in the southern hemisphere. The northern hemisphere determination is complete.

Comparison of magnetic observations in the Northern and Southern Hemispheres (summary only)

1977 ◽  
Vol 279 (963) ◽  
pp. 273-273
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Auroral Zone ◽  
Polar Night ◽  
Polar Caps ◽  
Magnetic Variation ◽  
A Current ◽  
Northern And Southern Hemispheres

A special feature of the regular daily magnetic variation S R at sub-auroral latitudes in both hemispheres can be considered as equivalent to the temporary flow, during a few hours of each U.T. day, of a current circulating all around the auroral zone (clockwise in the Northern Hemisphere, anticlockwise in the Southern Hemisphere); its intensity is the largest at the summer of each hemisphere. This current may be related to the S R variation inside the polar caps, which is deeply different from the S Pq described by Nagata and Kokubun (in fact, that variation is nothing but a residue of the S D variation on quiet days on these regions) and from the Mansurov— Svalgaard effect. The source of this phenomenon, an integrant part of the S R , is probably corpuscular since it still occurs during the polar night. Further investigations would be of great interest.

Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

2000 ◽  
Vol 179 ◽  
pp. 387-388
Author(s):  
Gaetano Belvedere ◽  
V. V. Pipin ◽  
G. Rüdiger
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Convection Zone ◽  
Solar Surface ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Magnetic Buoyancy ◽  
Alpha Effect ◽  
Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg &amp; Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg &amp; Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

scholarly journals First results of low frequency electromagnetic wave detector of TC-2/Double Star program

2005 ◽  
Vol 23 (8) ◽  
pp. 2803-2811 ◽  
Author(s):  
J. B. Cao ◽  
Z. X. Liu ◽  
J. Y. Yang ◽  
C. X. Yian ◽  
Z. G. Wang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Geomagnetic Storms ◽  
Low Frequency ◽  
Wave Detector ◽  
Ion Cyclotron Waves ◽  
Satellite Platform ◽  
Ion Cyclotron ◽  
First Results

Abstract. LFEW is a low frequency electromagnetic wave detector mounted on TC-2, which can measure the magnetic fluctuation of low frequency electromagnetic waves. The frequency range is 8 Hz to 10 kHz. LFEW comprises a boom-mounted, three-axis search coil magnetometer, a preamplifier and an electronics box that houses a Digital Spectrum Analyzer. LFEW was calibrated at Chambon-la-Forêt in France. The ground calibration results show that the performance of LFEW is similar to that of STAFF on TC-1. The first results of LFEW show that it works normally on board, and that the AC magnetic interference of the satellite platform is very small. In the plasmasphere, LFEW observed the ion cyclotron waves. During the geomagnetic storm on 8 November 2004, LFEW observed a wave burst associated with the oxygen ion cyclotron waves. This observation shows that during geomagnetic storms, the oxygen ions are very active in the inner magnetosphere. Outside the plasmasphere, LFEW observed the chorus on 3 November 2004. LFEW also observed the plasmaspheric hiss and mid-latitude hiss both in the Southern Hemisphere and Northern Hemisphere on 8 November 2004. The hiss in the Southern Hemisphere may be the reflected waves of the hiss in the Northern Hemisphere.

On a possible geological cause of changes in the position of the axis of the earth's crust

1867 ◽  
Vol 15 ◽  
pp. 46-54 ◽  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Earth’S Crust ◽  
The Subject ◽  
Earth's Crust ◽  
Geological Observation

At a time when the causes which have led to climatal changes in various parts of the globe are the subject of so much discussion, but little apology is needed for calling the attention of this Society to what possibly may have been one of these causes, though it has apparently hitherto escaped observation. That great changes of climate have taken place, at all events in the northern hemisphere of the globe, is one of the best established facts of geology, and that corresponding changes have not been noticed to the same extent in the southern hemisphere may possibly be considered as due, rather to a more limited amount of geological observation, than to an absence of the phenomena indicative of such alterations in climatal con­ditions having occurred.

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