Characteristics of Diurnal Pulses Observed in Typhoon Atsani Using Retrieved Cloud Property Data

Abstract

Using several cloud properties retrieved from the Himawari-8 satellite, combined with the best track storm center information, the temporal-spatial features of tropical cyclone (TC) diurnal pulses in 2015 Super Typhoon Atsani (T1516) are coherently depicted. To demonstrate the radially outward transition processes of the diurnal pulses from one cloud type to another, we divided high clouds into three types: opaque high cloud (OHC), cirrostratus (Cs), and cirrus (Ci). Two alternatively appeared peaks in cloud top height (CTH) within the storm central area and their corresponding outward pulses are identified. The first pulse covers a 24-hour period, it starts at ~0500−0700 local solar time (LST), with a gradual transition from OHC to Cs, then ends in Ci at around 0400 LST. The second pulse lasts for half a day and limited within 1000 km from the storm center. When the first CTH pulse ends in OHC, Cs, and Ci, their cloud fractional coverage and the outward expansion of large cloud optical thickness also reach maximum accordingly.

The Diurnal Cycle of Clouds in Tropical Cyclones over the Western North Pacific Basin

“…Numerous previous studies have pointed out that cirrus cloud coverage associated with TCs shows a diurnal cycle (e.g., Browner et al 1977;Muramatsu 1983;Lajoie and Butterworth 1984;Kossin 2002;Dunion et al 2014;Wang et al 2019). Using infrared imagery archive of TCs, Kossin (2002) found that diurnal oscillation of the cirrus canopy was evident over 300 km from the center of TCs, although it was weak near the storm center.…”