Publications
Filter Total Items: 7597
Some effects of quiet geomagnetic field changes upon values used for main field modeling Some effects of quiet geomagnetic field changes upon values used for main field modeling
The effects of three methods of data selection upon the assumed main field levels for geomagnetic observatory records used in main field modeling were investigated for a year of very low solar-terrestrial activity. The first method concerned the differences between the year's average of quiet day field values and the average of all values during the year. For H these differences were 2-3...
Authors
W.H. Campbell
Assessment of models proposed for the 1985 revision of the international geomagnetic reference field Assessment of models proposed for the 1985 revision of the international geomagnetic reference field
Geomagnetic measurements from land, marine and aerial surveys conducted in the years 1945-1964 were used to test the 14 models proposed as additions, for that period, to the series of definitive geomagnetic reference field (DGRF) models. Overall, NASA's 'SFAS' models and the BGS (British Geological Survey) models agree best with these data. Comparisons of the two proposed definitive main...
Authors
N.W. Peddie, A.K. Zunde
A chronology of U.S. Geological Survey hazards warnings: 1976-1986 A chronology of U.S. Geological Survey hazards warnings: 1976-1986
No abstract available.
Authors
Paula L. Gori, Clement F. Shearer
Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, October 1987 Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, October 1987
No abstract available.
Authors
John B. Townshend, R. V. O’Connell, L.Y. Torrence
Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, September 1987 Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, September 1987
No abstract available.
Authors
John B. Townshend, R. V. O’Connell, L.Y. Torrence
Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, February 1987 Preliminary geomagnetic data, College Observatory, Fairbanks, Alaska, February 1987
No abstract available.
Authors
John B. Townshend, R. V. O’Connell, L.Y. Torrence
Taking the pulse of Parkfield Taking the pulse of Parkfield
No abstract available.
Authors
R. A. Kerr
Earthquakes July-August 1986 Earthquakes July-August 1986
No abstract available.
Authors
Waverly J. Person
Current loops fitted to geomagnetic model spherical harmonic coefficients. Current loops fitted to geomagnetic model spherical harmonic coefficients.
One hundred-sixty circular current loops with radial axes were fitted by least squares to the 899 spherical harmonic coefficients of a 29th degree model. In the first case, the parameters that were fitted for each loop were the normalized magnetic moment, the distance from the center of the Earth to the current element, the colatitude and E. longitude of the loop axis, and one-half of...
Authors
L.R. Alldredge
On predicting changes in the geomagnetic field On predicting changes in the geomagnetic field
The present method of using constant secular variation rates to forecast magnetic components at a given site or to forecast spherical harmonic coefficients is known to be inaccurate. A new predictive method using trend and trigonometric functions fitted to known past values is used to extrapolate for a few years into the future. This provides an improvement over the usual linear...
Authors
L.R. Alldredge
On regional geomagnetic charts On regional geomagnetic charts
When regional geomagnetic charts for areas roughly the size of the United States were compiled by hand, some large local anomalies were displayed in the isomagnetic lines. Since the late nineteen sixties, when the compilation of charts using computers and mathematical models was started, most of the details available in the hand drawn regional charts have been lost. One exception to this...
Authors
L.R. Alldredge
Field guide to sedimentary structures in the Navajo and Entrada sandstones in southern Utah and northern Arizona Field guide to sedimentary structures in the Navajo and Entrada sandstones in southern Utah and northern Arizona
This field-trip guide describes the common sedimentary structures that occur in eolian sands. The outcrops that are described occur in the Navajo and Entrada Sandstones between the areas of Page, Arizona and St. George, Utah (figure I), but the sedimentary structures of these two sandstones are typical of most eolian deposits. The main part of the guide discusses the geologic setting and...
Authors
David M. Rubin, Ralph E. Hunter