The critical factor in controlling the auroral intensity in the cusp region as revealed by a statistical study on midday gap and non‐gap events

2021 ◽  
Author(s):  
Hui‐Xuan Qiu ◽  
De‐Sheng Han ◽  
Hui‐Ting Feng ◽  
Run Shi ◽  
Su Zhou ◽  
...  
Keyword(s):  
Statistical Study ◽  
Critical Factor ◽  
Cusp Region

scholarly journals A normalized statistical study of Earth’s cusp region based on nine-years of Cluster measurements

2020 ◽  
Vol 4 (3) ◽  
pp. 1-8
Author(s):  
Chao Xiao ◽  
◽  
WenLong Liu ◽  
DianJun Zhang ◽  
Zhao Zhang ◽  
...  
Keyword(s):  
Statistical Study ◽  
Cusp Region

scholarly journals Statistical study of ICME effects on Mercury's magnetospheric boundaries and northern cusp region from MESSENGER

2017 ◽  
Vol 122 (5) ◽  
pp. 4960-4975 ◽  
Author(s):  
Reka M. Winslow ◽  
Lydia Philpott ◽  
Carol S. Paty ◽  
Noé Lugaz ◽  
Nathan A. Schwadron ◽  
...  
Keyword(s):  
Statistical Study ◽  
Cusp Region ◽  
Magnetospheric Boundaries

scholarly journals <i>Letter to the Editor</i>A statistical study of the location and motion of the HF radar cusp

2002 ◽  
Vol 20 (2) ◽  
pp. 275-280 ◽  
Author(s):  
T. K. Yeoman ◽  
P. G. Hanlon ◽  
K. A. McWilliams
Keyword(s):  
Solar Wind ◽  
Continuous Monitoring ◽  
Large Scale ◽  
Statistical Study ◽  
Hf Radar ◽  
Auroral Ionosphere ◽  
Cusp Region ◽  
The North ◽  
Low Altitude ◽  
Spacecraft Data

Abstract. The large-scale and continuous monitoring of the ionospheric cusp region offered by HF radars has been exploited in order to examine the statistical location and motion of the equatorward edge of the HF radar cusp as a function of the upstream IMF BZ component. Although a considerable scatter is seen, both parameters have a clear influence from the north-south component of the IMF. Excellent agreement is achieved with previous observations from low altitude spacecraft data. The HF radar cusp region is seen to migrate equatorward at a rate of 0.02° min-1 nT-1 under IMF BZ south conditions, but remains static for IMF BZ north. The motion of the cusp implies an addition of magnetic flux of ~ 2 × 104 Wbs-1 nT-1 under IMF BZ south conditions, equivalent to a reconnection voltage of 20 kV nT-1, which is consistent with previous estimates from case studies on both the dayside and nightside regions.Key words. Ionosphere (auroral ionosphere) – Magnetospheric physics (magnetosphere-ionosphere interaction; solar wind magnetosphere interactions)

scholarly journals An investigation of latitudinal transitions in the SuperDARN Doppler spectral width parameter at different magnetic local times

2004 ◽  
Vol 22 (4) ◽  
pp. 1187-1202 ◽  
Author(s):  
G. Chisham ◽  
M. P. Freeman
Keyword(s):  
Key Words ◽  
Boundary Layers ◽  
Statistical Study ◽  
Spectral Width ◽  
Local Times ◽  
Magnetospheric Physics ◽  
Polar Cap ◽  
Cusp Region ◽  
Radar Network ◽  
Instruments And Techniques

Abstract. Latitudinal transitions from low to high Doppler spectral width in backscatter measured by the Super Dual Auroral Radar Network (SuperDARN) are now routinely used as proxies for the polar cap boundary (PCB) in the cusp-region ionosphere. In this paper we perform a statistical study of the nature of similar spectral width transitions at other magnetic local times (MLTs). This analysis illustrates that these latitudinal spectral width transitions exist at all magnetic local times, and that the latitude, gradient, and amplitude of the transitions vary systematically with MLT. In particular, the probability of a transition occurring at any latitude, identified independently in each MLT sector, is continuous with MLT from the cusp, through the morning sector, to the nightside. This suggests that the transition represents the PCB, as this is known to be what it represents in the cusp region. However, the picture in the afternoon sector (12:00-18:00 MLT) is more complex with no clearly preferred transition latitudes. Key words. Ionosphere (ionosphere-magnetosphere interactions; instruments and techniques). Magnetospheric physics (magnetopause, cusp, and boundary layers.)

scholarly journals Influence of magnetospheric processes on winter HF radar spectra characteristics

2002 ◽  
Vol 20 (11) ◽  
pp. 1783-1793 ◽  
Author(s):  
R. André ◽  
M. Pinnock ◽  
J.-P. Villain ◽  
C. Hanuise
Keyword(s):  
Statistical Study ◽  
Classification Scheme ◽  
Spectral Width ◽  
Hf Radar ◽  
Auroral Ionosphere ◽  
Plasma Convection ◽  
Ulf Wave ◽  
Cusp Region ◽  
Magnetospheric Cusp ◽  
The Relationship

Abstract. This study investigates further the relationship between regions of the magnetosphere and the characteristics of HF radar Doppler spectra recorded in the ionospheric projection of those regions. It builds on earlier work, which has reported a relationship between the Doppler spectral width and the ionospheric projection of the magnetospheric cusp region, by introducing novel techniques for classifying the Doppler spectra recorded by the SuperDARN radars. We first review the geophysical factors that can condition the characteristics of the autocorrelation function (ACF) data produced by the radars. This leads to a classification scheme of the ACF data which is then applied to a large database compiled from winter data taken by the Northern Hemisphere Super-DARN radars. This statistical study shows that the ACF characteristics are not randomly distributed in space, but rather are spatially organized in the ionosphere. This paper suggests that these regions are ordered primarily by the low energy (<approx> 1 keV) electron precipitation region and the presence of intense ULF wave activity.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; plasma convection)

Statistical Study of the Rotation Effect of Am Stars

1976 ◽  
Vol 32 ◽  
pp. 675-683
Author(s):  
Keiichi Kodaira
Keyword(s):  
Statistical Study ◽  
Rotation Velocity ◽  
General View ◽  
Slow Rotation ◽  
Rotation Effect

SummaryExcess of [m1] index of Am stars, relative to normal stars, is statistically found to be correlated with rotation velocity; the coefficient is estimated at ∆׀m1׀ /∆V(km/sec) ˜ - 0.0007 among Am stars. This result supports the general view that slow rotation is essential for Am phenomena.

A Method for Setting the Clearance Angle

1972 ◽  
Vol 30 ◽  
pp. 388-389
Author(s):  
Michael T. Bucek ◽  
Howard J. Arnott
Keyword(s):  
Experimental Evidence ◽  
Light Source ◽  
Black Spot ◽  
Critical Factor ◽  
Clearance Angle ◽  
Crude Approximation ◽  
Ultrathin Sections

It is believed by the authors, with supporting experimental evidence, that as little as 0.5°, or less, knife clearance angle may be a critical factor in obtaining optimum quality ultrathin sections. The degree increments located on the knife holder provides the investigator with only a crude approximation of the angle at which the holder is set. With the increments displayed on the holder one cannot set the clearance angle precisely and reproducibly. The ability to routinely set this angle precisely and without difficulty would obviously be of great assistance to the operator. A device has been contrived to aid the investigator in precisely setting the clearance angle. This device is relatively simple and is easily constructed. It consists of a light source and an optically flat, front surfaced mirror with a minute black spot in the center. The mirror is affixed to the knife by placing it permanently on top of the knife holder.

Sign in / Sign up

Export Citation Format

Share Document