Dr. Dunion presented a seminar titled “The Tropical Cyclone Diurnal Cycle: The Great Hurricane Exhale”.
New geostationary infrared satellite imagery has revealed a curious diurnal pulsing pattern in tropical cyclones (TCs) that may represent an unrealized, yet fundamental process of mature TCs. These diurnal pulses begin forming in the storm’s inner core near the time sunset each day and steadily propagate away from the storm overnight, reaching areas several hundred kilometers from the TC center by the following afternoon. There are marked changes in patterns of TC thermodynamics, winds, and precipitation as diurnal pulses develop and evolve each day. The timing and propagation of these TC diurnal pulses also appear to be linked to the diurnal cycle, making them remarkably predictable in time and space.
This talk will present satellite, numerical modeling, and observational perspectives pertaining to the TC diurnal cycle, including how it can be monitored, its evolution in time and space, its relevance to TC structure and intensity, and how it manifests in numerical simulations of TCs.
A recording of the presentation is available on the anonymous ftp site (screen appears 1 min 45 sec into recording): ftp://ftp.aoml.noaa.gov/hrd/pub/blog/seminars/2017/Dunion_HRD_Seminar_20170504.mp4