6.1 Lightning Occurrence and Casualties Relative to Crop Cycles in Bangladesh

Wednesday, 9 January 2019: 1:30 PM
North 225AB (Phoenix Convention Center - West and North Buildings)
Ronald L. Holle, Vaisala, Inc., Tucson, AZ; and A. Dewan, R. Said, W. A. Brooks, M. F. Hossain, and M. Rafiuddin

Very large numbers of lightning fatalities and injuries have been reported in the last several years during the pre-monsoon months in Bangladesh. A considerable amount of speculation has resulted about the reasons for this annual event. In order to provide improved information, data from the Global Lightning Dataset GLD360 network have been extracted for Bangladesh from 2013 through 2017. Over 34 million strokes have been detected during this period within the national boundary.

Lightning is clustered in April and May, when a third of the year’s lightning occurs. Lightning occurs often at all hours of the day, including the morning during this pre-monsoon period from March through May and the monsoon months of June through September. This very unusual diurnal cycle has not been seen elsewhere in the world to-date. The post-monsoon season has a typical afternoon maximum, while the winter has a nighttime lightning peak.

Lightning deaths are much more frequent in the pre-monsoon period, averaging 21 per day for the period of 1990-2017. The Monsoon season has eight deaths per day, and the post-monsoon and winter seasons have few. It is planned to develop a lightning fatality dataset to match the years of the GLD360 dataset.

Boro rice is harvested during the April-May time period when millions of people involved in labor-intensive manual agriculture during the daytime. It is planned to identify the districts of Bangladesh where the most people are involved in this crop during these months when, unfortunately, lightning is most common both morning and afternoon. Other crops will also be explored throughout the year to determine if boro rice is the main contributor to the large lightning fatality rate during April and May. As a result, the outdoor exposure of farming activities where there is no lightning protection may be defined more precisely by this study.

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