At ICSP long-term and transient effects of solar activity (e.g., Solar Lyman alpha, Solar flares) on the Earth's ionosphere dynamics are studied using a VLF network consisting of many receivers. Effects on the VLF signals due to solar flares are simulated using GEANT4 Monte-Carlo code coupled with the ionospheric chemistry and VLF propagation model

Typical example of detection of solar flares on NWC-IERC path.

Rate of electron production due to a typical M-class and X-class solar flare from GEANT4 code (for details see Palit et al., 2013).

Simulated results of VLF amplitude perturbations (dotted line) and corresponding observed VLF data (solid line) for M-class flare (left) and the corresponding variation of electron density at 74 km height over the Indian sub-continent at the flare peak time (right). .