Geomagnetism Program

Publications

Geomagnetism publications.

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Filter Total Items: 416
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Year Published: 2013

Geospace environment modeling 2008--2009 challenge: Dst index

This paper reports the metrics-based results of the Dst index part of the 2008–2009 GEM Metrics Challenge. The 2008–2009 GEM Metrics Challenge asked modelers to submit results for four geomagnetic storm events and five different types of observations that can be modeled by statistical, climatological or physics-based models of the magnetosphere-...

Rastätter, L.; Kuznetsova, M.M.; Glocer, A.; Welling, D.; Meng, X.; Raeder, J.; Wittberger, M.; Jordanova, V.K.; Yu, Y.; Zaharia, S.; Weigel, R.S.; Sazykin, S.; Boynton, R.; Wei, H.; Eccles, V.; Horton, W.; Mays, M.L.; Gannon, J.
Geospace environment modeling 2008--2009 challenge: Dst index; 2013; Article; Journal; Space Weather; Rastätter, L. ; Kuznetsova, M. M.; Glocer, A. ; Welling, D. ; Meng, X. ; Raeder, J. ; Wittberger, M. ; Jordanova, V. K.; Yu, Y. ; Zaharia, S. ; Weigel, R. S.; Sazykin, S. ; Boynton, R. ; Wei, H. ; Eccles, V. ; Horton, W. ; Mays, M. L.; Gannon, J.

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Year Published: 2013

The magnetic tides of Honolulu

We review the phenomenon of time-stationary, periodic quiet-time geomagnetic tides. These are generated by the ionospheric and oceanic dynamos, and, to a lesser-extent, by the quiet-time magnetosphere, and they are affected by currents induced in the Earth's electrically conducting interior. We examine historical time series of hourly magnetic-...

Love, Jeffrey J.; Rigler, Erin Joshua
The magnetic tides of Honolulu; 2013; Abstract or summary; Conference publication; Progress in EM Induction Studies of Crust and Mantle From Land, Sea, Air, and Space lll Posters; Love, Jeffrey J.;Rigler, Erin Joshua.

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Year Published: 2012

Credible occurrence probabilities for extreme geophysical events: earthquakes, volcanic eruptions, magnetic storms

Statistical analysis is made of rare, extreme geophysical events recorded in historical data -- counting the number of events $k$ with sizes that exceed chosen thresholds during specific durations of time $\tau$. Under transformations that stabilize data and model-parameter variances, the most likely Poisson-event occurrence rate, $k/\tau$,...

Love, Jeffrey J.
Credible occurrence probabilities for extreme geophysical events: earthquakes, volcanic eruptions, magnetic storms; 2012; Article; Journal; Geophysical Research Letters; Love, Jeffrey J.

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Year Published: 2012

Assessing the validity of station location assumptions made in the calculation of the geomagnetic disturbance index, Dst

In this paper, the effects of the assumptions made in the calculation of the Dst index with regard to longitude sampling, hemisphere bias, and latitude correction are explored. The insights gained from this study will allow operational users to better understand the local implications of the Dst index and will lead to future index formulations...

Gannon, Jennifer
Assessing the validity of station location assumptions made in the calculation of the geomagnetic disturbance index, Dst; 2012; Article; Journal; Space Weather; Gannon, Jennifer

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Year Published: 2012

Geomagnetic detection of the sectorial solar magnetic field and the historical peculiarity of minimum 23-24

[1] Analysis is made of the geomagnetic-activityaaindex covering solar cycle 11 to the beginning of 24, 1868–2011. Autocorrelation shows 27.0-d recurrent geomagnetic activity that is well-known to be prominent during solar-cycle minima; some minima also exhibit a smaller amount of 13.5-d recurrence. Previous work has shown that the recent solar...

Love, Jeffrey J.; Rigler, J.
Geomagnetic detection of the sectorial solar magnetic field and the historical peculiarity of minimum 23-24; 2012; Article; Journal; Geophysical Research Letters; Jeffrey J Love;Rigler, J.

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Year Published: 2012

INTERMAGNET and magnetic observatories

A magnetic observatory is a specially designed ground-based facility that supports time-series measurement of the Earth’s magnetic field. Observatory data record a superposition of time-dependent signals related to a fantastic diversity of physical processes in the Earth’s core, mantle, lithosphere, ocean, ionosphere, magnetosphere, and, even, the...

Love, Jeffrey J.; Chulliat, Arnaud
INTERMAGNET and magnetic observatories; 2012; Article; Journal; EPOS Newsletter; Love, Jeffrey J.; Chulliat, Arnaud

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Year Published: 2012

John B. "Jack" Townshend (1927-2012)

Jack Townshend, geophysicist and dedicated public servant, died on 13 August 2012 in Fairbanks, Alaska. He was 85. Jack's career with the federal government, most of it with the national magnetic observatory program, spanned more than six solar cycles of time, and he retired only days before his death. The duration of Jack's career encompassed an...

Love, Jeffrey J.; Finn, Carol A.
John B. "Jack" Townshend (1927-2012); 2012; Article; Journal; Eos, Transactions American Geophysical Union; Love, Jeffrey J.; Finn, Carol A.

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Year Published: 2012

Uncovering the nonadiabatic response of geosynchronous electrons to geomagnetic disturbance

We describe an energy spectrum method for scaling electron integral flux, which is measured at a constant energy, to phase space density at a constant value of the first adiabatic invariant which removes much of the variation due to reversible adiabatic effects. Applying this method to nearly a solar cycle (1995 - 2006) of geosynchronous electron...

Gannon, Jennifer; Elkington, Scot R.; Onsager, Terrance G.
Uncovering the nonadiabatic response of geosynchronous electrons to geomagnetic disturbance; 2012; Article; Journal; Journal of Geophysical Research; Gannon, Jennifer; Elkington, Scot R.; Onsager, Terrance G.

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Year Published: 2012

Problem of the Love‐Gannon relation between the asymmetric disturbance field and Dst

Love and Gannon (2009) discovered that statistically, over a fifty year period the difference in the dawn and dusk disturbance‐field H component at low latitudes (hourly averaged) is linearly proportional to Dst. If the difference is designated by δDD in units of nT/RE, then the Love‐Gannon (L‐G) relation is δDD...

Siscoe, G. L.; Love, Jeffrey J.; Gannon, J.L.

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Year Published: 2012

Superposed epoch analysis and storm statistics from 25 years of the global geomagnetic disturbance index, USGS-Dst

Statistics on geomagnetic storms with minima below -50 nanoTesla are compiled using a 25-year span of the 1-minute resolution disturbance index, U.S. Geological Survey Dst. A sudden commencement, main phase minimum, and time between the two has a magnitude of 35 nanoTesla, -100 nanoTesla, and 12 hours, respectively, at the 50th percentile level....

Gannon, J.L.
Superposed epoch analysis and storm statistics from 25 years of the global geomagnetic disturbance index, USGS-Dst; 2012; OFR; 2012-1167; Gannon, J.L.

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Year Published: 2012

On the reported ionospheric precursor of the Hector Mine, California earthquake

Using Global Positioning System (GPS) data from sites near the 16 Oct. 1999 Hector Mine, California earthquake, Pulinets et al. (2007) identified anomalous changes in the ionospheric total electron content (TEC) starting one week prior to the earthquake. Pulinets (2007) suggested that precursory phenomena of this type could be useful for...

Thomas, J.N.; Love, J.J.; Komjathy, A.; Verkhoglyadova, O.P.; Butala, M.; Rivera, N.
On the reported ionospheric precursor of the Hector Mine, California earthquake; 2012; Article; Journal; Geophysical Research Letters; Thomas, J. N.; Love, J. J.; Komjathy, A. ; Verkhoglyadova, O. P.; Butala, M. ; Rivera, N.

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Year Published: 2012

Sunspot random walk and 22-year variation

We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-...

Love, Jeffrey J.; Rigler, E. Joshua
Sunspot random walk and 22-year variation; 2012; Article; Journal; Geophysical Research Letters; Love, Jeffrey J.; Rigler, E. Joshua