Falling Trend of Winter Lightning Over Western India and Its Possible Relation With Western Disturbances

Abstract

During the Indian winter, the southerly propagation of cold air at middle and upper altitudes is caused by a trough in westerly jet streams due to the effect of Western Disturbances (WDs). Sometimes, this advection of cold and dry air above near-surface moist and warm air can make the atmosphere conditionally unstable. Therefore, these WDs are associated with thunderstorm formation and lightning activity over northern India (north of 20° north); however, occasionally, the effect of WDs extends up to the entry point of southern India. The satellite and ground-based observations of lightning over western India (15.5°–22°N, 72.5°–81°E) over two decades (1997–2023) observed a falling trend of winter lightning at the rate of −0.02 (LIS/OTD), and −0.06 (ILLN) flashes km−2 year−1, respectively. Our observation suggested that the majority of lightning and thunderstorm activity is primarily initiated by WDs during winter; however, the incursion of moisture from the surrounding oceans also plays a crucial role in producing severe weather and precipitation over the study region. Many researchers and our observations have shown a decreasing trend of WD frequencies and winter precipitation over the Indian region. This paper addresses important aspects of climate change as lightning activity and thunderstorm days decreased steadily over western India, suggesting the falling trend is possibly linked to the weakening and reduced frequency of WDs from 1997 to 2023. While global trends suggest increasing lightning with climate change, this study reveals a decreasing trend in lightning activity, highlighting the uneven regional impacts of climate change.