Tomographic reconstruction of ionospheric electron density based on constrained algebraic reconstruction technique

A constrained algebraic reconstruction technique (CART) is proposed for the tomographic reconstruction of the ionospheric electron density distribution. The method uses a popular two-dimensional multi-point finite difference approximation of the second order Laplace operator to provide the constraint matrix. The tomographic results of a numerical simulation show that the reconstruction accuracy of electron density distribution is significantly improved. A careful validation of the reliability and superiority of CART is made. Finally, we applied the new method to the analysis of actual Global Navigation Satellite Systems (GNSS) observations and compared the results with ionosonde observation of Wuhan station.