First results on forecasting the spatial occurrence pattern of L-band scintillation and its temporal evolution

Abstract

After a fairly successful attempt to forecast the temporal evolution of L-band scintillation over a given location, Trivandrum (8.5° N, 76.91° E, dip latitude 0.5° N) (Sridharan et al., 2012, J. Atmos. Sol. Terr. Phys. 80 230–238; Bagiya et al., 2014, J. Atmos. Sol. Terr. Phys. 110–111, 15–22), an attempt has been made here to generate the spatial–temporal maps of the occurrence pattern of L-band scintillation over the Indian region. To start with, the day time fluctuations in [f0F2]2 are used to forecast the temporal evolution of perturbations during the course of the night over Trivandrum. Similar to the earlier studies, here too it is taken that the electron density perturbations retain their characteristics throughout night and traverse with a uniform velocity. This implies that when the integrity of wave train of electron density perturbations is retained, any particular feature that passes over Trivandrum would have crossed over another location west of Trivandrum at an earlier time only dictated by the zonal velocity. With this assumption it becomes feasible to generate the probable spatial and temporal pattern of L-band scintillation. The consequences/limitations of the above assumptions are discussed in detail. The observed relation between the total duration of spread-F and the base height of the F-region (h'F) at 1930 LT has been explained in terms of the favourable background neutral atmospheric conditions. Following Bagiya et al. (2013, J. Geophys. Res. 118, 1–8), the relation between h'F at 1930 LT and the probable maximum latitudinal extent of the spread-F enables specification of the upper limit for the latitudes likely to be affected by the scintillation. It is believed that the presented results hold enough potential to generate the reliable L-band scintillation forecast maps and provide the necessary alerts to the satellite based air navigation users.