Relationships between total lightning, deep convection, and tropical cyclone intensity change

Abstract

AbstractThis study investigates the characteristics of total lightning in the inner core (INCO, 0–100 km) and outer rainband (OB, 200–400 km) of tropical cyclones (TC). Relationships between flash density (FLD), convective intensity, and TC intensity change are further examined. FLD shows a bimodal structure with a strong maximum in the eyewall (INCO, 0–50 km) and a secondary maximum in the OB. FLD maximizes under conditions of warmest sea surface temperature (SST) and large values of vertical wind shear. Compared to OB FLD, INCO FLD is less sensitive to SST increase but shows greater variability in relation to shear. Intensifying TCs have substantially lower INCO (but higher OB) FLD compared to weakening and neutral TCs. Similar trends are shown in radar quantities (volume of 30 dBZ echoes in the mixed phase). rapidly intensifying (RI) TCs also show significantly smaller FLD and VOL30 than slowly intensifying TCs, indicating the potential of these parameters in forecasting RI. INCO (OB) FLD decreases (increases) 12–18 h preceding the onset of RI, while INCO (OB) FLD increases (decreases) 6–12 h prior to TC weakening. These relationships between lightning and TC intensity change (+24 h) are generally maintained regardless of prior (−24 h) TC intensity change status. However, convective depth and vertically integrated ice content in the INCO increased preceding TC intensification, suggesting the lack of supercooled liquid content and establishment of glaciated conditions (evident by an increase in the 20 dBZ and decrease in the 30 dBZ echo volume) in the INCO of intensifying TCs, especially RI.