Modeling Post-Sunset Equatorial Spread-F Occurrence as a Function of Evening Upward Plasma Drift Using Logistic Regression, Deduced from Ionosondes in Southeast Asia

The occurrence of post-sunset equatorial spread-F (ESF) could have detrimental effects on trans-ionospheric radio wave propagation used in modern communications systems. This problem calls for a simple but robust model that accurately predicts the ESF. Logistic regression was implemented to daily ESF as function evening upward plasma drift (v). use logistic is formalized by y^=1/[1+exp(−z)], where y^ represents probability occurrence, and z linear containing v. value v derived from vertical motion bottom side F-region ionosphere, which observed ionosondes Southeast Asia. Data points (938) were collected equinox seasons 2003 2016. training set 70% dataset derive remaining 30% test performance y^. expression z=−2.25+0.14v obtained set, y^≥0.5 (v ≥ ~16.1 m/s) y^<0.5 < represented non-occurrence ESF, respectively, with an accuracy ~0.8 true skill score (TSS) ~0.6. Similarly, testing shows TSS Further analysis suggested z-function can be reliable F10.7 levels ranging 60 140 solar flux units. (y^) found this study novel technique predict occurrence. consistency between concludes values proposed mathematical nowcasting or ESFs.