Further Evidence of the Tropical Cyclone Diurnal Cycle

Recent work has identified a potentially fundamental process in mature tropical cyclones (TCs) referred to as the tropical cyclone diurnal cycle. The TC diurnal cycle is characterized by a dramatic radial expansion of the TC cloud field (i.e. diurnal pulse) that begins propagating away from the storm around local sunset each day, eventually reaching areas hundreds of kilometers from the storm by the following afternoon. Observations and model simulations are now suggesting that diurnal pulses likely involve a deep vertical layer of the troposphere and are often characterized by marked changes in TC structure as they propagate away from the storm. This presentation will highlight satellite detection of the TC diurnal cycle, how the TC diurnal cycle appears to manifest in numerical simulations, and examples of TC diurnal pulses observed by the NOAA P-3 lower fuselage (LF) radar.