A Comparison of Vertical Cosmic-Ray Cutoff Rigidities as Calculated with Different Geomagnetic Field Models PDF Download
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Author: M. A. Shea
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
The calculated values of cutoff rigidities determined by the trajectory-tracing technique are dependent upon which geomagnetic field model is used. In the past 20 years a number of geomagnetic field models have become available. In general each model is derived to fit the magnetic field data appropriate to a specific epoch with some of the more recent models containing time derivatives so that the models are applicable over a number of years. In the past the applicability of some models has been questioned inasmuch as small, but nevertheless significant, differences in vertical cutoff rigidities have been calculated with the different field models. The authors have used the time derivatives of the International Geomagnetic Reference Field model to calculate a selected set of vertical cutoff rigidities appropriate for Epoch 1955.0 and find that in general these values compare favorably with the results previously obtained using the Finch and Leaton 1955.0 field model. From these results and other epoch comparisons, it is found that vertical cutoff rigidities are essentially the same when calculated using comparable field models for the same epoch.
Author: M. A. Shea
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
The calculated values of cutoff rigidities determined by the trajectory-tracing technique are dependent upon which geomagnetic field model is used. In the past 20 years a number of geomagnetic field models have become available. In general each model is derived to fit the magnetic field data appropriate to a specific epoch with some of the more recent models containing time derivatives so that the models are applicable over a number of years. In the past the applicability of some models has been questioned inasmuch as small, but nevertheless significant, differences in vertical cutoff rigidities have been calculated with the different field models. The authors have used the time derivatives of the International Geomagnetic Reference Field model to calculate a selected set of vertical cutoff rigidities appropriate for Epoch 1955.0 and find that in general these values compare favorably with the results previously obtained using the Finch and Leaton 1955.0 field model. From these results and other epoch comparisons, it is found that vertical cutoff rigidities are essentially the same when calculated using comparable field models for the same epoch.
Author: M. A. Shea
Publisher:
ISBN:
Category : Geomagnetism
Languages : en
Pages : 16
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Book Description
Author: M. A. Shea
Publisher:
ISBN:
Category : Cosmic rays
Languages : en
Pages : 102
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Book Description
Tables of cosmic-ray cutoff rigidities using the trajectory-tracing technique are given for five Epochs of the geomagnetic field. These values have been determined utilizing the International Geomagnetic Reference Field with time derivatives applied so that the coefficients for the field model are appropriate for the following Epochs: 1955.0, 1965.0, 1966.5, 1970.0, and 1975.0. Each table includes the geographic coordinates and L value of each location together with the main cutoff rigidity, the Stormer cutoff rigidity, and the effective cutoff rigidity. Tables for both vertical and non-vertical directions are included, as well as a listing of the FORTRAN computer program used to calculate these values. (Author).
Author: Lev Dorman
Publisher: Springer Science & Business Media
ISBN: 1402092393
Category : Science
Languages : en
Pages : 770
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Book Description
The problem of cosmic ray (CR) geomagnetic effects came to the fore at the beg- ning of the 1930s after the famous expeditions by J. Clay onboard ship (Slamat) between the Netherlands and Java using an ionization chamber. Many CR la- tude expeditions were organized by the famous scientists and Nobel Laureates R. Millikan and A. Compton. From the obtained latitude curves it follows that CRs cannot be gamma rays (as many scientists thought at that time), but must be charged particles. From measurements of azimuthally geomagnetic effect at that time it also followed that these charged particles must be mostly positive (see Chapter 1, and for more details on the history of the problem see monographs of Irina Dorman, M1981, M1989). The ?rst explanations of obtained results were based on the simple dipole - proximation of the geomagnetic ?eld and the theory of energetic charged particles moving in dipole magnetic ?elds, developed in 1907 by C. Stormer ̈ to explain the aurora phenomenon. Let us note that it was made about 5 years before V. Hess discovered CRs, and received the Nobel Prize in 1936 together with K. Anderson (for the discovery of CR and positrons in CR).
Author: M. S. Shea
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
The location of the cosmic-ray equator for two different epochs has been determined by calculating the vertical cutoff rigidities in the equatorial region using geomagnetic field models appropriate for 1965 and 1975. A comparison of these results with the cosmic-ray equator determined for Epoch 1955 shows that whereas no significant changes for this 20-year interval are found in the longitudes between 0 degrees and 270 degrees E, the theoretical equator has shifted slightly northward in the longitude range 280 degrees to 350 degrees E.
Author: M. A. Shea
Publisher:
ISBN:
Category : Asymptotes
Languages : en
Pages : 112
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Book Description
Tables of asymptotic directions and vertical cutoff rigidities for a selected set of cosmic-ray stations are presented. These values were obtained by the integration of vertically incident cosmic-ray trajectories through the International Geomagnetic Reference Field model adjusted for a 1975.0 Epoch. The table of asymptotic directions contains the asymptotic latitudes and longitudes that specify the direction of approach from interplanetary space of a cosmic-ray particle. These asymptotic directions are given for specific rigidities above the main cone cutoff rigidity for each station, and at 0.01 GV rigidity intervals throughout the penumbra. Maps of the asymptotic directions for each station are also included. The table of vertical cutoff rigidities contains the geographic coordinates and L value of each cosmic-ray station together with the main cone cutoff rigidity, the Stormer cutoff rigidity, and the effective cutoff rigidity. (Author).
Author: M. A. Shea
Publisher:
ISBN:
Category : Cosmic magnetic fields
Languages : en
Pages : 68
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Book Description
Tables of cosmic-ray cutoff rigidities using the trajectory-tracing technique are given for three epochs of the geomagnetic field. These values have been determined utilizing the International Geomagnetic Reference Field with time derivatives applied so that the coefficients for the field model are appropriate for the following epochs: 1965.0, 1970.0, and 1975.0. Each table includes the geographic coordinates and L value of each location together with the main cutoff rigidity, the Stormer cutoff rigidity, and the effective cutoff rigidity. The altitude for which each set of values was calculated is also given. Tables for both vertical and non-vertical directions are included. These cutoff rigidity values are supplemental to those published in previous AFGL reports. In addition, minor corrections to previously published values are also included.
Author: M. A. Shea
Publisher:
ISBN:
Category : Computer simulation
Languages : en
Pages : 104
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Book Description
Tables of asymptotic directions and vertical cutoff rigidities for a selected set of cosmic-ray stations are presented. These values were obtained by the integration of vertically incident cosmic-ray trajectories through the Finch and Leaton (Epoch 1955) quiescent model of the geomagnetic field. The table of asymptotic directions contains the asymptotic latitudes and longitudes that specify the direction of approach from interplanetary space of a cosmic-ray particle. These asymptotic directions are given for specific rigidities above the main cone cutoff rigidity for each station, and at 0.01 GV rigidity intervals throughout the penumbra. Maps of the symptotic directions for each station are included. The table of vertical cutoff rigidities contains the geographic coordinates and L value of each cosmic-ray station together with the main cone cutoff rigidity, the Stoermer cutoff rigidity, and the effective cutoff rigidity. (Author).
Author: M. A. Shea
Publisher:
ISBN:
Category : Cosmic rays
Languages : en
Pages : 96
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Book Description
Tables of vertical cutoff rigidities calculated using the trajectory-tracing technique are given for two epochs of the geomagnetic field. The Finch and Leaton magnetic field coefficients were used for Epoch 1955, and the Jensen and Cain coefficients were used for Epoch 1960. Each table includes the geographic coordinates and L value of each location together with the main cone cutoff rigidity, the Stormer cutoff rigidity, and the effective cutoff rigidity. Data for approximately 2900 locations on the earth are presented.
Author: M. A. Shea
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
An updated five by fifteen degree world grid of trajectory-derived vertical cutoff rigidities for Epochs 1965 and 1975 has been calculated using the International Geomagnetic Reference Field with time derivatives applied for a 1975.0 Epoch. A comparison of these vertical cutoff rigidities with those calculated for Epoch 1955.0 shows that whereas minor changes in the cutoff rigidities (or about equal 0.20 GV) occur in many areas of the world over this 20-year interval, major changes ( 0.60 GV) occur in the Central and Southern Atlantic Ocean area and over the Central and South American land masses. While the changes in the Southern Hemisphere are primarily decreases in the vertical cutoff rigidities, there is an area in the Northern Hemisphere, principally in the Atlantic Ocean, where comparable increases in the vertical cutoff rigidities are calculated.
