Ms. Stevenson presented a seminar on the “Lightning Observations in Atlantic and East Pacific TCs”.
Global lightning detection has become more reliable in the past decade, allowing for comprehensive observational studies on lightning activity in TCs over the open oceans. This seminar will highlight interesting results from analyses of TCs in the Atlantic and East Pacific from 2005–2014 using the World Wide Lightning Location Network (WWLLN).
The main focus will be on recent results pertaining to inner core (0–100 km) lightning “bursts” and subsequent intensity changes. A case study of Hurricane Earl (2010) found that the occurrence of an inner core lightning burst does not necessarily lead to TC weakening, as some recent studies have suggested. Thus, the relationship between inner core lightning bursts and future intensity change patterns were analyzed in a large ten-year sample of TCs. The dependence of future intensity change was investigated for three factors: the radial burst location, the azimuthal burst location, and the prior intensity change.
Additionally, two other topics will be discussed. First, a diurnal cycle of lightning was observed in some, but not all, major hurricanes, with a radially outward propagation speed similar to the diurnal cycle observed in satellite imagery by Dunion et al. (2014). Second, the azimuthal distribution of lightning varied significantly from the expected shear-dominant relationship when the deep-layer vertical wind shear vector opposed the storm motion vector in East Pacific TCs.
A recording of the presentation is available on the anonymous ftp site: