Improvement of automatic scaling of vertical incidence ionograms by simulated annealing

•Simulated annealing algorithm is presented for automatic scaling of iomograms.•Amount of candidate ionogram traces will not be built in our automatic scaling method.•The automatic scaling method improved by SA can scale ionograms recorded at different locations.

The ionogram autoscaling technique is very important for facilitating the statistical investigation of the ionosphere. Jiang et al. (2013) proposed an autoscaling technique for extracting ionospheric characteristics from vertical incidence ionograms. However, extensive efforts are invested in continuously improving the performance of that. The simulated annealing (SA) is used to improve the autoscaling technique in this paper. To be capable of automatic scaling of ionograms recorded at different locations, the SA is applied instead of Empirical Orthogonal Functions (EOFs) to search the best-fit parameters in the autoscaling technique. In order to validate the improvement of this autoscaling technique, ionograms recorded at Wuhan (30.5°N, 114.3°E), Puer (22.7°N, 101.05°E) and Leshan (29.6°N, 103.75°E) are investigated by comparing the autoscaled results with the values scaled by an operator. Results show that the presented work is efficient for scaling of ionograms recorded at different geographic positions. Moreover, the additional procedure can improve the accuracy of the autoscaling technique compared to results presented by Jiang et al. (2013).