HR: 1330h
AN: SA12B-1096    [PDF]
TI: A Two-Step Lag-Profile-Based Approach to the Inversion of the Incoherent Scatter Radar Data
AU: * Nikoukar, R
EM: nikoukar@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1308 West Main, Urbana, IL 61801 United States
AU: Sulzer, M P
EM: msulzer@naic.edu
AF: National Astronomy and Ionosphere Center, Rt625 Bo Esperanza, Arecibo, 00612 Puerto Rico
AU: Kamalabadi, F
EM: farzadk@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1308 West Main, Urbana, IL 61801 United States
AU: Kudeki, E
EM: erhan@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1308 West Main, Urbana, IL 61801 United States
AB: The extraction of altitude profiles of ionospheric parameters such as electron density, electron temperature, ion temperature, and ion fractions from the incoherent scatter radar (ISR) measurements requires careful consideration of two main aspects of the inversion process. The first is due to the range smearing effect of the radar pulse on the information from one altitude over a range of altitudes, and the second is due to the nonlinear relationship between the parameters and measured spectra. We propose a two-step lag-profile-based method for accurate and efficient parameter estimation from ISR data. The first step consists of the computation of the incoherent scatter autocorrelation function (ACF) from a set of 1-D deconvolutions. We exploit regularization techniques to overcome the problems associated with the ill-conditioned nature of the convolution matrix. Estimation of the parameters from the resulting incoherent scatter ACF using non-linear least-squares fitting methods forms the second step. Furthermore, as simulations reveal, using two or more pulses improves the deconvolution process by reducing the inherent ambiguity in the range smearing operation. We have developed a technique using a pair of simple amplitude-modulated sequences that has superior performance over a pair of long pulses. The nonlinear least squares fitting of the deconvolved lag-profiles may be accomplished for one height at a time or for an altitude model (such as polynomial) of the ionospheric parameters at a limited range of altitudes. We consider the suitability of each alternative for the inversion of the Arecibo World Day data. Results demonstrate improved spatial resolution obtained while reducing the computational complexity.
DE: 2400 IONOSPHERE
DE: 2494 Instruments and techniques
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting