Advances in Magnetospheric Radio Wave Analysis and Tomography

J. L. Green (1), S. A. Cummer (2), B. W. Reinisch (3), S. F. Fung (1), 
M. L. Kaiser (4), R. Mutel (5), J. Pickett (5), I. Christopher (5), and 
D. A. Gurnett (5)

1. Space Science Data Operations Office, NASA Goddard Space Flight Center, 
   Greenbelt, Maryland
2. Electrical and Computer Engineering Department, Duke University, Durham, 
   North Carolina
3. Center for Atmospheric Research, University of Massachusetts-Lowell, 
   Lowell, Massachusetts
4. Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, 
   Greenbelt, Maryland
5. Dept. of Physics and Astronomy, University of Iowa, Iowa City, Iowa


A number of experiments have been accomplished in which the Radio Plasma 
Imager (RPI) on the IMAGE spacecraft was used as a low frequency radio wave 
transmitter and the WAVES instrument on WIND and the Wide-band instruments on 
all four CLUSTER spacecraft as receivers.  These transmissions/receptions 
provide a unique opportunity to test a number of important magnetospheric 
measurement techniques. For instance, the RPI transmissions to the four 
Cluster spacecraft are being used to precisely calibrate differential delays 
for the Cluster AKR source location and motion studies using VLBI. This 
technique is extremely useful since it is the only direct method of 
determining the instrumental delays and other errors in the analysis leading 
to uncertainties in source location.  The RPI/Wave experiments are being used 
to verify and test the feasibility of magnetospheric radio tomography by 
measuring inter-spacecraft electromagnetic wave propagation parameters such 
as intensity, phase, and Faraday rotation measurements. The path-integrated 
electron density/magnetic field products can be unambiguously measured from 
these, low signal to noise ratio, single and dual frequency measurements.  
In light of these successful results, the potential scientific value of 
multi-spacecraft radio tomographic imaging of the magnetosphere for future 
missions will also be discussed.

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Presented at the 34th COSPAR Scientific Assembly, Houston, Texas, U.S.A.  
10-19 October 2002