HR: 08:00h
AN: SH11B-01    [PDF]
TI: A New Method for Studying the Solar Wind Using Radio Scintillations (IPS)
AU: * Coles, W A
EM: bcoles@ucsd.edu
AF: University of California, E.C.E. Dept., La Jolla, CA 92093-0407 United States
AU: Harmon, J K
EM: harmon@naic.edu
AF: Arecibo Observatory, HC3 Box53995, Arecibo, PR 00612 United States
AU: Rickett, B J
EM: rickett@ece.ucsd.edu
AF: University of California, E.C.E. Dept., La Jolla, CA 92093-0407 United States
AU: Venkataraman, A
EM: arun@naic.edu
AF: Arecibo Observatory, HC3 Box53995, Arecibo, PR 00612 United States
AB: Intensity scintillations (IPS) have been used to measure the velocity and the micro-structure of the solar wind for many years. Observations with a single antenna are simple and easily arranged, but they provide only one-dimensional information on the microstructure and they are subject to bias if the microstructure is anisotropic or the scattering becomes ``strong.'' Observations with two or more antennas provide a two-dimensional measure of the microstructure; a vector velocity; and they are more robust in the onset of strong scattering. However there are few suitable arrays and they are difficult to schedule. In either case a reliable estimate requires that many time scales be observed - typically about 10 minutes of observation. Here we report a robust new method which requires only one antenna, but is not sensitive to either anisotropic structure or strong scattering. Furthermore a reliable speed estimate can be made in about 2 s. The method obviously requires additional data - the intensity must be measured with a multi-channel spectrometer. Fortunately such spectrometers are standard equipment at radio observatories. The resulting dynamic spectra can be processed to show the 2-dimensional microstructure and the flow speed. Theory, simulations, and observations will be presented to demonstrate the method. It appears particularly suitable for measuring transients such as coronal mass ejections (CME's) in the interplanetary medium. It will be possible to track many sources with a single antenna, spending only a few seconds on each source, and thus to map the space-time evolution of the CME in turbulence level, flow speed, and anisotropy.
DE: 2149 MHD waves and turbulence
DE: 2164 Solar wind plasma
DE: 2194 Instruments and techniques
DE: 7513 Coronal mass ejections
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting