Download or read book A Five by Fifteen Degree World Grid of Calculated Cosmic-Ray Vertical Cutoff Rigidities for 1965 and 1975 written by M. A. Shea and published by . This book was released on 1975 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.