W. 1. Axford, J. Geophys. Res, vol.73, 1968.

A. M. Persoon, D. A. Gurnett, and S. D. Sbawhan, , p.123, 1983.

S. B. Ganguli, Rev. Geophys, vol.34, p.311, 1996.

T. E. Moore, Space ScL Rev, vol.71, p.409, 1995.

C. R. Chappell, T. E. Moore, and J. H. Waite, J. Geophys. Res, vol.92, p.5896, 1987.

R. A. Kerr, Science, vol.242, p.377, 1988.

M. H. Acusa, Space ScL Rev, vol.71, p.5, 1995.

P. J+harvey, , p.583

S. 1. Ganguli, H. G. Mitchelljr, and P. J. Palmadesso, Planet. Space Sci, vol.35, p.703, 1987.

H. G. Mitchelljr, S. B. Ganguli, and P. J. Palmadesso, J. Geophys.Res, vol.97, 120451992.

C. J. Pollock, , p.18969, 1990.

J. H. Whitteker, Planet.Space Sci, vol.25, p.773, 1977.

J. L. Horwitz and M. Lockwood, J. Geophys. Res, vol.90, p.9749, 1985.

L. A. Frank, K. L. Ackerson, and D. M. Yeager, , vol.82, p.129, 1977.

M. Candidi, S. Orsini, and J. L. Horwitz, , p.14401, 1988.

T. Al, Geophys. Res.Lett, vol.21, p.1023, 1994.

M. Hirahara, J. Geophys. Res, vol.101, p.7769

A. W. Yau, W. K. Peterson, and E. G. Shelley, Geophys. Menogr. Ser, vol.44, p.211, 1988.

, whose insightsand leadership were pivotal inthe design ofTIDE.Supported bythe NASAGlobal Geospace Science Program at Goddard Space Flight Center, by NASA grant NAG5-3182 at the Universityof California,and by the NASA Office of Space Flightat theMarshallSpace FlightCenter. The authors are indebted to the technical staffs of their institutions for development of the TIDE and PSI hardware and software

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, www.sctencemag.org ? SCIENCE ? VOL, vol.277, 1997.