Comparing IRI and regional ionospheric model with ionosonde foF2 measurements in Pakistan

Critical frequency of F2 layer acquired by three ionosonde stations, Karachi (KHI, 24.95°N, 67.13°E), Multan (MUL, 30.18°N, 71.48°E) & Islamabad (ISL, 33.75°N, 73.13°E), in Pakistan has been compared with foF2 obtained from global ionospheric model IRI-2012 and computed from regional ionospheric model using higher terms of Emperical Orthogonal Functions (EOFs) during summer (July). The data has been compared at different phases of solar epoches. The computational sets using higher number of terms of EOFs (L > 1) showed slight different deviations from observations with respect to the expansion of EOFs using least number of terms (L = 1). Both models revealed good to reasonable agreement with the observed values for Multan and Islamabad. However for Karachi, considerable deviations between the models and observations are noted at different solar epoches except deep solar minimum due to its location which lies within equatorial ionization anomaly region. In general, regional model gives better results compared to IRI for MUL and ISL whereas IRI worked better for Karachi. Thus further improvements in regional model are required to get promosing results especially for EIA region station.