WHISTLER AND Z-MODE ECHOES FROM RADIO SOUNDING ON THE IMAGE SATELLITE

D. L. Carpenter, Stanford

V. S. Sonwalkar, U. of Alaska Fairbanks

T. F. Bell, Stanford

U. S. Inan, Stanford

M. A. Spasojevic, Stanford

R. F. Benson, GSFC

B. W. Reinisch. U. Mass. Lowell

Discrete whistler mode echoes

L=4

L=4

Diffuse whistler-mode echoes

Z mode echoes: cases when plasma frequency is larger than the gyrofrequency, common within the plasmasphere

fp fUHR

fp

Z mode echoes: cases when gyrofrequency exceeds the plasma frequency, common poleward of the plasmapause and at low altitudes

fz fp

fg fUHR

Z mode gone mad?

fZ

Conclusions:1. RPI on IMAGE has received both discrete and widely time-

spread whistler mode echoes at altitudes of several thousand km in the southern hemisphere.

2. The discrete events are being used for study of plasma density and structure in the inner plasmasphere and low altitude polar regions.

3. The time spread echoes can be used to investigate meter scale density irregularities in the polar regions.

4. RPI efficiently excites the Z mode in a way that can provide useful information on plasma density along and near the IMAGE orbit, as well as on issues affecting the coupling between the Z mode and the free space O mode.

At last! A VLF transmitter in space!

Good grief! A VLF transmitter in space!

Don Carpenter, Vikas Sonwalkar, Maria Spasojevic, Tim Bell, Umran Inan, Bill Taylor, Bodo Reinisch, Bob Benson, etc.