资源环境科技发展态势分析平台

We explore the physical reasons behind the pronounced contrast in the probability of lightning over land and ocean. For decades, from a multitude of platforms, it has been observed that lightning is much rarer over the ocean, and throughout the literature, many have offered physical and environmental hypotheses to explain this dichotomy. Focusing on the tropical oceans, we apply a new ground-based approach using feature tracking software to radar data from the Kwajalein atoll in the tropical west Pacific Ocean. As seen in satellite-based approaches in the same region, features with lightning tend to be much larger and persist much longer than those without. Lightning occurs on average 40min into the tracked life cycle of the features. Within those 40min, features with lightning exhibit rapid development of layers of high radar reflectivity at and above the freezing level, as would be consistent with electrification. Traditional environmental parameters, such as convective available potential energy or total column water vapor, show only weak relationships to the probability of the features to develop lightning or to grow to large sizes, until the probabilities are examined on daily time scales and on larger (synoptic) spatial scales. We present an environmental and evolutionary case study over Kwajalein, and within a longer time frame and within a synoptic forcing context, convective organization appears to play a role in the development of deep oceanic precipitating features and their tendency to become sufficiently strong as to develop lightning.