Lightning/Landscape Interactions in Interior Alaska

Dorte Dissing

We found a strong positive correlation between the distribution of lightning strike density and boreal forest. This relationship was consistent at the scales of the entire region of interior Alaska and within 2-degree longitudinal transects. We also found that lightning strikes occurring in tundra were usually relatively close to the boreal forest/tundra boundary. A manuscript based on this research was submitted to the Canadian Journal of Forest Research.

Based on tower flux measurements, there is a significant difference in sensible heat flux between black spruce forest and a burned area. A mesoscale climate model has been used to speculated that the difference between a burn scare and the surrounding forest may promote convection and ultimately lightning. We used a lightning strike database to test whether the normalized rate of lightning strikes increased near large burn scars after wildfire. The results were mixed. One problem was that it is impossible to find large unburned regions in interior Alaska that subsequently contain an isolated, large burn scar. We have found some convective clouds that appear to developed in association with burn scars. We are investigating multi-temporal observations from same day sequential images such as passes from Landsat-5/Landsat-7/Terra.