Publications
Geomagnetism publications.
Filter Total Items: 411
Missing data and the accuracy of magnetic-observatory hour means
Analysis is made of the accuracy of magnetic-observatory hourly means constructed from definitive minute data having missing values (gaps). Bootstrap sampling from different data-gap distributions is used to estimate average errors on hourly means as a function of the number of missing data. Absolute and relative error results are calculated for horizontal-intensity, declination, and vertical-comp
Authors
Jeffrey J. Love
Total field sensor comparison
During the XIIIth IAGA Workshop (hereafter referred to as “the workshop"), several total field comparison measurements were conducted at the Boulder Magnetic Observatory (BOU). The purpose of these tests was to look for errors within the total field instruments which are considered “absolutes” instruments. The total field measurement is a critical component of the absolute measurement computation.
Authors
Tim White
Earth's magnetic field complex: U.S. National activities during the Decade of Geopotential Field Research
The US geomagnetism community is supported by NASA, NOAA, USGS, NSF, DOD, and US universities. During the Decade of Geopotential Field Research, inaugurated in 1999 with the launch of the Danish satellite Ørsted on a US rocket, the US community has been involved in satellite mission development and analysis, instrument development, model development, and in the discovery and understanding of new p
Authors
Michael E. Purucker, T. Sabaka, W. Kuang, S. Maus, Jeffrey J. Love
Geomagnetic observations on tristan da cunha, south atlantic ocean
Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37?? 05' S, 12?? 18' W, is therefore of crucial importance. We have conducted several sets of repeat station measurements during magnetically quiet condition
Authors
J. Matzka, N. Olsen, C.F. Maule, L.W. Pedersen, A.M. Berarducci, S. Macmillan
On the reported magnetic precursor of the 1993 guam earthquake
Using 1-second magnetometer data recorded 67 km from the epicenter of the 1993 Mw 7.7 Guam earthquake, Hayakawa et al. (1996) and Miyahara et al. (1999) identify anomalous precursory changes in ultra-low frequency magnetic polarization (the ratio of vertical to horizontal field components). In a check of their results, we compare their data (GAM) with 1-second data from the Kakioka observatory (KA
Authors
J.N. Thomas, J.J. Love, M.J.S. Johnston, K. Yumoto
On the reported magnetic precursor of the 1989 Loma Prieta earthquake
Among the most frequently cited reports in the science of earthquake prediction is that by Fraser-Smith et al. (1990) and Bernardi et al. (1991). They found anomalous enhancement of magnetic-field noise levels prior to the 18 October 1989 Loma Prieta earthquake in the ultra-low-frequency range (0.0110-10.001 Hz) from a ground-based sensor at Corralitos, CA, just 7 km from the earthquake epicenter.
Authors
J.N. Thomas, J.J. Love, M.J.S. Johnston
In situ measurements of contributions to the global electrical circuit by a thunderstorm in southeastern Brazil
The global electrical circuit, which maintains a potential of about 280??kV between the earth and the ionosphere, is thought to be driven mainly by thunderstorms and lightning. However, very few in situ measurements of electrical current above thunderstorms have been successfully obtained. In this paper, we present dc to very low frequency electric fields and atmospheric conductivity measured in t
Authors
J.N. Thomas, R.H. Holzworth, M.P. McCarthy
Revised Dst and the epicycles of magnetic disturbance: 1958-2007
A revised version of the storm-time disturbance index Dst is calculated using hourly-mean magnetic-observatory data from four standard observatories and collected over the years 1958-2007. The calculation algorithm is a revision of that established by Sugiura et al., and which is now used by the Kyoto World Data Center for routine production of Dst. The most important new development is for the re
Authors
J.J. Love, J.L. Gannon
Monitoring the Earth's dynamic magnetic field
The mission of the U.S. Geological Survey's Geomagnetism Program is to monitor the Earth's magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research into the nature of geomagnetic variations for purposes
Authors
Jeffrey J. Love, David Applegate, John B. Townshend
Lightning‐driven electric fields measured in the lower ionosphere: Implications for transient luminous events
Transient luminous events above thunderstorms such as sprites, halos, and elves require large electric fields in the lower ionosphere. Yet very few in situ measurements in this region have been successfully accomplished, since it is typically too low in altitude for rockets and satellites and too high for balloons. In this article, we present some rare examples of lightning‐driven electric field c
Authors
Jeremy N. Thomas, Benjamin H. Barnum, Erin Lay, Robert H. Holzworth, Mengu Cho, Michael C. Kelley
Magnetic monitoring of earth and space
For centuries, navigators of the world’s oceans have been familiar with an effect of Earth’s magnetic field: It imparts a directional preference to the needle of a compass. Although in some settings magnetic orientation remains important, the modern science of geomagnetismhas emerged from its romantic nautical origins and developed into a subject of great depth and diversity. The geomagnetic field
Authors
Jeffrey J. Love
Rare measurements of a sprite with halo event driven by a negative lightning discharge over Argentina
As part of a collaborative campaign to investigate Transient Lummous Events (TLEs) over South America, coordinated optical, ELF/VLF, and lightning measurements were made of a mesoscale thunderstorm observed on February 22-23, 2006 over northern Argentina that produced 445 TLEs within a ???6 hour period. Here, we report comprehensive measurements of one of these events, a sprite with halo that was
Authors
M.J. Taylor, M.A. Bailey, P.D. Pautet, S.A. Cummer, N. Jaugey, J.N. Thomas, N.N. Solorzano, Sabbas F. Sao, R.H. Holzworth, O. Pinto, N.J. Schuch