The dependence of muon intensity on the geomagnetic latitude

1970 ◽  
Vol 234 (1) ◽  
pp. 17-22 ◽  
Author(s):  
D. P. Bhattacharyya
Keyword(s):  
Geomagnetic Latitude ◽  
Muon Intensity

scholarly journals Statistical study of medium-scale traveling ionospheric disturbances in low-latitude ionosphere using an automatic algorithm

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Pin-Hsuan Cheng ◽  
Charles Lin ◽  
Yuichi Otsuka ◽  
Hanli Liu ◽  
Panthalingal Krishanunni Rajesh ◽  
...  
Keyword(s):  
Climate Model ◽  
Geomagnetic Latitude ◽  
Detection Algorithm ◽  
Support Vector ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Low Latitude ◽  
Total Electron ◽  
Medium Scale ◽  
Traveling Ionospheric Disturbances

AbstractThis study investigates the medium-scale traveling ionospheric disturbances (MSTIDs) statistically at the low-latitude equatorial ionization anomaly (EIA) region in the northern hemisphere. We apply the automatic detection algorithm including the three-dimensional fast Fourier transform (3-D FFT) and support vector machine (SVM) on total electron content (TEC) observations, derived from a network of ground-based global navigation satellite system (GNSS) receivers in Taiwan (14.5° N geomagnetic latitude; 32.5° inclination), to identify MSTID from other waves or irregularity features. The obtained results are analyzed statistically to examine the behavior of low-latitude MSTIDs. Statistical results indicate the following characteristics. First, the southward (equatorward) MSTIDs are observed almost every day during 0800–2100 LT in Spring and Winter. At midnight, southward MSTIDs are more discernible in Summer and majority of them are propagating from Japan to Taiwan. Second, northward (poleward) MSTIDs are more frequently detected during 1200–2100 LT in Spring and Summer with the secondary peak of occurrence between day of year (DOY) 100–140 during 0000–0300 LT. The characteristics of the MSTIDs are interpreted with additional observations from radio occultation (RO) soundings of FORMOSAT-3/COSMIC as well as modeled atmospheric waves from the high-resolution Whole Atmosphere Community Climate Model (WACCM) suggesting that the nighttime MSTIDs in Summer is likely connected to the atmospheric gravity waves (AGWs).

Statistics of pulsating auroras on the basis of all-sky TV data from five stations. I. Occurrence frequency

1981 ◽  
Vol 59 (8) ◽  
pp. 1150-1157 ◽  
Author(s):  
T. Oguti ◽  
S. Kokubun ◽  
K. Hayashi ◽  
K. Tsuruda ◽  
S. Machida ◽  
...  
Keyword(s):  
Local Time ◽  
Cold Plasma ◽  
Geomagnetic Latitude ◽  
Auroral Oval ◽  
Magnetic Activity ◽  
Occurrence Frequency ◽  
Frequency Of Occurrence ◽  
Occurrence Probability ◽  
Energetic Electrons ◽  
Plasma Irregularities

The frequency of occurrence of pulsating auroras is statistically examined on the basis of all-sky TV data for 34 nights from five stations, in a range from 61.5 to 74.3° in geomagnetic latitude. The results are that: (1) occurrence probability of a pulsating aurora is 100% after 4 h in geomagnetic local time, (2) pulsating auroras occur in the morning hours along the auroral oval even when magnetic activity is as small as 0o ≤ Kp ≤ 1, (3) pulsating auroras occur even in the evening when Kp increases to greater than 3−, (4) drift of pulsating auroras is westward in the evening while it is eastward in the morning hours, (5) the region of pulsating auroras splits into two zones, 64 to 68° and 61 to 63° in geomagnetic latitude, after 4 h geomagnetic local time for Kp from 2o to 3−, and the splitting also appears to exist for greater Kp as evidenced by observation other than our auroral data. These results are discussed in relation to distributions of cold plasma irregularities and energetic electrons in the magnetosphere.

scholarly journals Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

2013 ◽  
Vol 31 (11) ◽  
pp. 2097-2121 ◽  
Author(s):  
P. M. E. Décréau ◽  
S. Kougblénou ◽  
G. Lointier ◽  
J.-L. Rauch ◽  
J.-G. Trotignon ◽  
...  
Keyword(s):  
Electric Field ◽  
Circular Polarization ◽  
Source Region ◽  
Plane Waves ◽  
Geomagnetic Latitude ◽  
Magnetic Activity ◽  
Spectral Signature ◽  
Time Interval ◽  
Field Polarization ◽  
Electric Field Polarization

Abstract. The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km) from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m) antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE). This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC) waves in the 15–25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair) combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the dawn sector, at a large L value (L ~ 10) and a medium geomagnetic latitude (35° S). We discuss these untypical results within the frame of the geophysical conditions prevailing that day, i.e. a particularly quiet long time interval, followed by a short increase of magnetic activity.

scholarly journals Vertical muon intensity measured with MACRO at the Gran Sasso laboratory

1995 ◽  
Vol 52 (7) ◽  
pp. 3793-3802 ◽  
Author(s):  
M. Ambrosio ◽  
R. Antolini ◽  
G. Auriemma ◽  
R. Baker ◽  
A. Baldini ◽  
...  
Keyword(s):  
Muon Intensity

scholarly journals Topside Ionosphere and Plasmasphere Modelling Using GNSS Radio Occultation and POD Data

2021 ◽  
Vol 13 (8) ◽  
pp. 1559
Author(s):  
Fabricio S. Prol ◽  
M. Mainul Hoque
Keyword(s):  
Solar Activity ◽  
Electron Density ◽  
Radio Occultation ◽  
Geomagnetic Latitude ◽  
Low Earth Orbit ◽  
Activity Level ◽  
Topside Ionosphere ◽  
Electron Content ◽  
Total Electron ◽  
Solar Activity Level

A 3D-model approach has been developed to describe the electron density of the topside ionosphere and plasmasphere based on Global Navigation Satellite System (GNSS) measurements onboard low Earth orbit satellites. Electron density profiles derived from ionospheric Radio Occultation (RO) data are extrapolated to the upper ionosphere and plasmasphere based on a linear Vary-Chap function and Total Electron Content (TEC) measurements. A final update is then obtained by applying tomographic algorithms to the slant TEC measurements. Since the background specification is created with RO data, the proposed approach does not require using any external ionospheric/plasmaspheric model to adapt to the most recent data distributions. We assessed the model accuracy in 2013 and 2018 using independent TEC data, in situ electron density measurements, and ionosondes. A systematic better specification was obtained in comparison to NeQuick, with improvements around 15% in terms of electron density at 800 km, 26% at the top-most region (above 10,000 km) and 26% to 55% in terms of TEC, depending on the solar activity level. Our investigation shows that the developed model follows a known variation of electron density with respect to geographic/geomagnetic latitude, altitude, solar activity level, season, and local time, revealing the approach as a practical and useful tool for describing topside ionosphere and plasmasphere using satellite-based GNSS data.

scholarly journals Influence of high-latitude geomagnetic pulsations on recordings of broadband force-balanced seismic sensors

2012 ◽  
Vol 1 (2) ◽  
pp. 85-101 ◽  
Author(s):  
E. Kozlovskaya ◽  
A. Kozlovsky
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Geomagnetic Latitude ◽  
Low Frequency ◽  
Auroral Oval ◽  
Polar Regions ◽  
Geomagnetic Pulsations ◽  
Seismic Sensors ◽  
Magnetic Poles ◽  
Magnetic Disturbances

Abstract. Seismic broadband sensors with electromagnetic feedback are sensitive to variations of surrounding magnetic field, including variations of geomagnetic field. Usually, the influence of the geomagnetic field on recordings of such seismometers is ignored. It might be justified for seismic observations at middle and low latitudes. The problem is of high importance, however, for observations in Polar Regions (above 60° geomagnetic latitude), where magnitudes of natural magnetic disturbances may be two or even three orders larger. In our study we investigate the effect of ultra-low frequency (ULF) magnetic disturbances, known as geomagnetic pulsations, on the STS-2 seismic broadband sensors. The pulsations have their sources and, respectively, maximal amplitudes in the region of the auroral ovals, which surround the magnetic poles in both hemispheres at geomagnetic latitude (GMLAT) between 60° and 80°. To investigate sensitivity of the STS-2 seismometer to geomagnetic pulsations, we compared the recordings of permanent seismic stations in northern Finland to the data of the magnetometers of the IMAGE network located in the same area. Our results show that temporary variations of magnetic field with periods of 40–150 s corresponding to regular Pc4 and irregular Pi2 pulsations are seen very well in recordings of the STS-2 seismometers. Therefore, these pulsations may create a serious problem for interpretation of seismic observations in the vicinity of the auroral oval. Moreover, the shape of Pi2 magnetic disturbances and their periods resemble the waveforms of glacial seismic events reported originally by Ekström (2003). The problem may be treated, however, if combined analysis of recordings of co-located seismic and magnetic instruments is used.

scholarly journals Observed Auroral Ovals Secular Variation Inferred from Auroral Boundary Data

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 351
Author(s):  
Bruno Zossi ◽  
Hagay Amit ◽  
Mariano Fagre ◽  
Ana G. Elias
Keyword(s):  
High Frequency ◽  
Field Model ◽  
Geomagnetic Latitude ◽  
Auroral Zone ◽  
Secular Change ◽  
Polar Cap ◽  
High Frequency Signal ◽  
Area Increase ◽  
Northern And Southern Hemispheres

We analyze the auroral boundary corrected geomagnetic latitude provided by the Auroral Boundary Index (ABI) database to estimate long-term changes of core origin in the area enclosed by this boundary during 1983–2016. We design a four-step filtering process to minimize the solar contribution to the auroral boundary temporal variation for the northern and southern hemispheres. This process includes filtering geomagnetic and solar activity effects, removal of high-frequency signal, and additional removal of a ~20–30-year dominant solar periodicity. Comparison of our results with the secular change of auroral plus polar cap areas obtained using a simple model of the magnetosphere and a geomagnetic core field model reveals a decent agreement, with area increase/decrease in the southern/northern hemisphere respectively for both observations and model. This encouraging agreement provides observational evidence for the surprising recent decrease of the auroral zone area.

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