Bottomside profile shape parameters during low solar activity and comparisons with IRI-2007 model

Modern digital ionosonde measurements at low-middle latitude station, New Delhi, India, are used to assess the IRI-2007 model for the bottomside profile shape parameters B0 and B1 during solar minimum. Comparative analysis shows that in general, the IRI (B0 Table) option reveals better agreement with the B0 observations during daytime in all the seasons, while outside this time period, the IRI (Gulyaeva) predicted B0 values are closer to the observations. For 131 parameter, both the options in the IRI reproduce similar diurnal variations in all the seasons and are closer to observed values except during pre-sunrise and post-sunset hours. (C) 2009 Elsevier Ltd. All rights reserved.