open access

https://hdl.handle.net/2115/57923

Characterization of Lightning Occurrence in Alaska Using Various Weather Indices for Lightning Forecasting

英語

Moisture

2011-06

Fuji Technology Press

Journal of Disaster Research

6(3)

343-355

Alaska lost 10% of its forest area due to vigorous forest fires in 2004 and 2005. Repeated lightning-caused forest fires annoy residents and influencing earth’s atmosphere in every fire season. The authors have reported on the weather conditions of Alaska’s most severe lightning occurrence in mid June 2005. This paper examines a range of weather indices like soar, instability, ‘dry lightning’ and others to the factors that could clearly explain lightning characteristics in Alaska. First, lightning occurrence days from May to September were classified into ‘non or small lightning’ days and ‘lightning’ days to determine threshold values. Second, ‘lightning’ days were categorized into ‘less severe’, ‘severe’, ‘very severe’, and ‘extremely severe’ to notice controlling factors on the lightning severity. Based on this analysis, the lifted index (LIFT) was selected as sensitive to assess upper air instability, and Te850 (environmental temperature at 850hPa) was selected as sensitive to assess warm and moist air masses. Finally, the possibilities of lightning forecasts in Alaska are discussed using lightning occurrence and LIFT and Te850 in 2005. As there is a time-lag between LIFT measurements (14:00) and the lightning peak (~17:00), and around one day time-lag between Te850 and lightning occurrence, lightning forecasts using LIFT and Te850 could provide a simply applicable forecast index for Alaska.

学術雑誌論文

Accepted Manuscript

1881-2473

1883-8030