Photo Credit: Mike Trenchard, Earth Sciences & Image Analysis Laboratory, NASA Johnson Space Center. Hurricane Isabel in September 2003, as seen from the International Space Station. GLM Flash Data Trends During Tropical Cyclone Intensification Changes David J. PeQueen Eric C. Bruning 9 September 2020 GLM Science Team Meeting Saffir-Simpson Hurricane Wind Tropical Cyclone Intensity Scale Category Winds [kt] Rapid Intensification 1 64-82 • 30 kt or greater increase in max TC sustained wind in a 24-hr period 2 83-95 • Needs warm sea surface temperatures and low wind shear 3 96-112 4 113-136 Radius of Maximum Wind (RMW) 5 137+ 2005-2014 TCs in FLIGHT+ data set. ICLB radial position relative to the RMW (Stevenson et al. 2018, Fig. 1). Stern et al. (2015) finds in idealized numerical simulations that “most contraction is completed prior to most intensification” NA TCs 24-hr intensity change (Stevenson et al. 2018, Fig. 5). Photo Credit: nesdis.noaa.gov/content/hurricane-dorian-2019 Hurricane Dorian (2019 NA) Peak intensity: 910 mb; 160 kt (Category 5) on Sept. 1 Minimum Pressure [mb] Wind Speed [kt] 1020 160 990 120 960 930 80 900 40 0 50 100 150 0 50 100 150 Hours Since 2019 08 27 18 00 UTC Hours Since 2019 08 27 18 00 UTC Determining the Radius of Maximum Wind Dorian Average RMW [km] 35 30 25 20 15 10 5 0 0 20 40 60 80 100 Hours Since 2019 August 30, 13 UTC Hurricane Dorian Strengthening (2019 NA) Dramatic shift in core lightning characteristics that is less evident in the rainband flashes • AFA decrease • TOE decrease Weakening Hurricane Strengthening Erick (2019 ENP) Minimum Pressure [mb] Peak intensity: 1020 952 mb; 115 kt Strengthening 1000 (Category 4) 980 on Jul. 30-31 960 940 0 20 40 60 80 100 120 • Big spike in FED Hours Since 2019 07 28 12 00 UTC around time of Wind Speed [kt] peak intensity 120 100 • TOE decrease Weakening 80 60 • AFA slight 40 increase 20 0 20 40 60 80 100 120 Hours Since 2019 07 28 12 00 UTC Upcoming Diurnal Cycle in Dorian Work ⮚Complete pixel statistics for GLM- era systems (both NA & ENP) with RMW divisions and manual track corrections as needed ⮚Characterize diurnal cycle effect on pixel statistics • Minimum detected TOE.