The Evolution of Microphysical Characteristics of a Rainband during its reorganization in Typhoon Matmo (2014)

Typhoon Matmo (2014) made the landfall at 07:30 July 23, 2014 (UTC) in the coastal area of Fuqing in Fujian Province as a severe thunderstorm; then it moved inland weakening. The convection in Matmo was organized into an arc-shaped rainband with trailing stratiform precipitation to the inner side during the period from 08:00 to 15:00 July 24. It was, for the first time in China, well captured by an S-band polarimetric radar (LSRD) located in Lishui, Jiangsu Province. This study examines the evolution of microphysical characteristics of the rainbaind of Typhoon Matmo (2014) using the polarimetric radar observations. Four different periods of the rainband were investigated: 1) onset stage (S1, 08:00-10:00), 2) rapid developing stage (S2, 10:00-11:30), 3) mature stage (S3, 11:30-13:00), and 4) dissipating stage (S4, 13:00-15:00). Composite statistics of the rainband was examined in terms of hydrometeor type classification and contoured frequency by altitude diagrams (CFADs) of reflectivity (Z), differential reflectivity (Z_DR), correlation coefficient (ρ_hv) and specific differential phase (K_DP). In S1, the rainband presented more stratiform signatures. In S2, supercooled liquid water was presented and more snow particles were generated above melting layer due to the strong updrafts. Large variability of hydrometeor types is shown above melting layer in this stage. In S3, the rainband was purely convective with its echo top over 16 km and more snow particles between 6 km – 9 km height. The hydrometeor was almost uniformly distributed above melting layer with snow particles between 6 km – 9 km and ice crystal above 9km. The rainband weakened gradually in S4 in terms of the echo top, precipitation, et al. Quantitative analysis of DSD retrieved from LSRD indicated that the DSDs from this rainband inland were mainly a maritime convective type during the whole. For the four stages, the drop size increased gradually with the average mass-weighted diameter D_m of about 1.1 mm, 1.52 mm, 1.67 mm, and 1.7 mm, respectively. And the average logarithmic normalized intercepts N_w were about 4.97, 4.32, 4.28, and 4.1 log10 mm^-1 m^-3, respectively.