Index Catalog // ScholarsArchive@OSU

Creator:: Egbert, Gary D.
Abstract:: We describe novel hybrid algorithms for inversion of electromagnetic geophysical data, combining the computational and storage efficiency of a conjugate gradient approach with an Occam scheme for regularization and step-length control. The basic algorithm is based on the observation that iterative solution of the symmetric (Gauss-Newton) normal equations with conjugate...
Resource Type:: Article
Full Text:: gji_5523_LR Geophysical Journal International Geophys. J

Creator:: Egbert, Gary D.
Abstract:: I derive probability densities for virtual geomagnetic pole( VGP) longitudes for a general statistical model of local magnetic field variations. I show that even for very simple statistically homogeneous models of secular variation, the distribution of VGP longitudes is peaked 90° away from the sampling longitude. Thus, when sites are...
Resource Type:: Article
Full Text:: , VOL. 19, NO. 23, PAGES 2353-2356, DECEMBER 2, 1992 SAMPLING BIAS IN VGP LONGITUDES Gary D. Egbert

Creator:: Balasis, Georgios and Egbert, Gary D.
Abstract:: Although satellite electromagnetic induction studies have usually assumed a symmetric magnetospheric ring current source, there is growing evidence for significant source asymmetry. Here we apply empirical orthogonal function methods to mid-latitude night-side hourly mean geomagnetic observatory data to search for evidence of nonzonal low-frequency source fields. The dominant spatial mode...
Resource Type:: Article
Full Text:: studies Georgios Balasis1 and Gary D. Egbert2 Received 24 January 2006; revised 24 March 2006; accepted

Creator:: Ray, Richard D., Eanes, R. J., Egbert, Gary D., and Pavlis, N. K.
Abstract:: The most accurate determinations of the global ocean tides are currently based on altimeter measurements made by the Topex/Poseidon satellite. The error spectrum corresponding to the M₂ tidal solution is here estimated, primarily by inverse methods and secondarily by simple differencing in flatter than tidal signal spectrum, and it exceeds...
Resource Type:: Article
Full Text:: ocean tide R. D. Ray, • R. J. Eanes, 2 G. D. Egbert, 3 and N. K. Pavlis 4 Abstract. The most

Creator:: Patro, Prasanta K. and Egbert, Gary D.
Abstract:: In conjunction with the USArray component of EarthScope, long period magnetotelluric (MT) data are being acquired in a series of arrays across the continental US. Initial deployments in 2006 and 2007 acquired data (10– 10,000 s) at 110 sites covering the US Pacific Northwest, distributed with the same nominal spacing...
Resource Type:: Article
Full Text:: . Patro1,2 and Gary D. Egbert1 Received 11 July 2008; revised 27 September 2008; accepted 1 October 2008

Creator:: Ray, Richard D. and Egbert, Gary D.
Abstract:: How and where the ocean tides dissipate their energy are longstanding questions with both oceanographic and astronomical implications. Two decades ago, Doake suggested that flexing of Antarctic ice shelves by the underlying ocean tide is an important energy sink, perhaps accounting for over half the global dissipation rate. Observational constraints...
Resource Type:: Article
Full Text:: 60øS Richard D. Ray Hughes STX, NASA Goddard Space Flight Center, Greenbelt, Maryland Gary D

Creator:: Zaron, Edward D. and Egbert, Gary D.
Abstract:: The interaction of the dominant semidiurnal M₂ internal tide with the large-scale subtidal flow is examined in an ocean model by propagating the tide through an ensemble of background fields in a domain centered on the Hawaiian Ridge. The background fields are taken from the Simple Ocean Data Assimilation (SODA)...
Resource Type:: Article
Full Text:: Ridge Time-Variable Refraction of the Internal Tide at the Hawaiian Ridge Zaron, Edward D., Gary D

Creator:: Egbert, Gary D. and Ray, Richard D.
Abstract:: New empirical estimates of the long-period fortnightly (Mf) tide obtained from TOPEX/Poseidon (T/P) altimeter data confirm significant basin-scale deviations from equilibrium. Elevations in the low-latitude Pacific have reduced amplitude and lag those in the Atlantic by 308 or more. These interbasin amplitude and phase variations are robust features that are...
Resource Type:: Article
Full Text:: Tides from Equilibrium: Kinematics and Geostrophy GARY D. EGBERT College of Oceanic and Atmospheric

Creator:: Ray, Richard D. and Egbert, Gary D.
Abstract:: The small S₁ ocean tide is caused primarily by diurnal atmospheric pressure loading. Its excitation is therefore unlike any other diurnal tide; in particular, pressure loading is maximum near the equator where the diurnal gravitational potential is zero. The global character of the S₁ tide is here determined by numerical...
Resource Type:: Article
Full Text:: . RAY Laboratory for Terrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, Maryland GARY D

Creator:: Balasis, Georgios, Egbert, Gary D., and Maus, Stefan
Abstract:: The current satellite magnetic missions offer new opportunities to determine the electrical conductivity of the Earth. However, satellites are nearly stationary in local time and therefore sample the inducing and induced fields quite differently than geomagnetic observatories, which rotate with the Earth. We show that estimates of induction transfer functions...
Resource Type:: Article
Full Text:: electromagnetic induction transfer functions Georgios Balasis,1 Gary D. Egbert,2 and Stefan Maus1,3,4 Received

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