The low-latitude ionospheric tomography network (LITN) - initial results

The Low-latitude Ionospheric Tomography Network (LITN), a chain of six stations located along the 121 degrees E meridian receiving signals from the Transit NNSS satellites, carries out tomographic investigations of the ionosphere in this equatorial anomaly region. The technical aspects of the network are introduced. Because of the steep latitudinal gradients of the ionosphere in this region, a special procedure has been developed to facilitate the reconstruction process. Model simulations are carried out to help formulate the best reconstruction algorithm. Initial results from the first set of data from the full network are presented, and the diurnal behavior of the anomaly discussed. Comparisons of the reconstructed electron density profiles with those derived from ionograms and the reconstructed vertical TECs with those observed appear to indicate that the LITN can be used to provide a two-dimensional image of the ionosphere in the equatorial region. (C) 1997 Elsevier Science Ltd.