Expression for Calculation of Lightning Ground Flash Density for Conditions of India

The ground flash density is the number of lightning strikes to ground per square kilometer per year. If no measurements of the ground flash density for specific area are available, this parameter can be roughly estimated from the annual number of thunderstorm days with a help of several well-known expressions. Indian standard IS 2309 indicates the relationship between thunderstorm days per year and lightning flashes per square kilometer per year for several thunderstorm day values. According to Indian standard IS 2309, the Indian annual thunderstorm days count is ranging from 1 to 103. Approximation of ground flash density based on standard data was made, allowing calculation of cloud-to-ground lightning flash density in the whole range of thunderstorm days for conditions of India. The resulting expression more closely matches the data of the standard than other known expressions.