Frequency and intensity of lighting on the Indian subcontinent increasing with global warming: IITM study
Amid global warming, the frequency and intensity of lightning strikes over the Indian subcontinents are expected to increase, according to a study by scientists from the Indian Institute of Tropical Meteorology (IITM).
The study was published in the international journal “Journal of Atmospheric and Solar-Terrestrial Physics” in May this year. The research “First study of cloud-to-ground lightning discharges using ground-based observations over the Indian subcontinent and its possible relationship with carbon dioxide and aerosols”, revealed that from 2009 to 2011, the lightning flash density (LFD) showed an increasing trend.
Dr Adarsh Dube, scientist at IITM and author of the study, said there is enough data to reflect the increase in lightning frequency and intensity. However, this study also highlights how the interaction of carbon dioxide and aerosols affects lightning.
“Cloud-to-ground (CG) illumination is defined as the lightning discharge between the thundercloud and the ground. CG lightning is what people see. LFD is defined as lightning per square kilometer per year. It is used to study the raw lightning count data The LFD is improved by 20% in 2010 and 13% in 2011 compared to that of 2009 on the east sector On the west coast, there is an increase of 30% in 2010 and 17% in 2011. On the Bay of Bengal, there is an increase of up to 66% in LFD at a few locations over the two years,” Dube said.
Regarding the concentration of aerosols and carbon dioxide, the study showed that when aerosols and carbon dioxide increase, the LFD increases.
The paper states, “There is an increase in the amount of mole fraction of carbon dioxide from 2009 to 2010 and then into 2011. The increase in the mole fraction of carbon dioxide fuels atmospheric heating and thus leads to increased convection . The intensity of the convection leads to the generation of charged particles and thus the initiation of lightning discharges. According to reports from the Intergovernmental Panel on Climate Change (IPCC), carbon dioxide in the atmosphere increases atmospheric temperature which drives the frequency of thunderstorms and lightning,” the study states.
The study further highlights that a significant improvement in carbon dioxide concentration is reported in the years 2010 and 2011 compared to 2009. “This increase in carbon dioxide concentration correlates very well with the improvement in the LFD . In addition, a substantial increase in aerosol concentration is also seen,” the study states.
Dube added that the frequency and intensity of lightning in a few parts of India are higher.
“In the western parts of Punjab, the northeastern region near Sundarban, showed an increase in lightning. In the interior of India, the Chota Nagpur Plateau, which comprises a large part of Jharkhand state as well as adjoining parts of Chhattisgarh, Odisha, West Bengal and Bihar, the coastal region from Malbar to Konkan has shown an increase in LFD over the years,” Dube said.
The study follows many parts of India reporting lightning and thunderstorms during this season.