Two types of precipitation particle distribution in convective cells accompanying a Baiu frontal rainband around Okinawa Island, Japan

Abstract

[1] Polarimetric radar variables and ground-based raindrop size distributions (DSDs) of two convective cells in a Baiu frontal rainband over the Okinawa region were analyzed to clarify the precipitation particle distributions in convective cells with low echo top heights. One cell existed in the stratiform rain zone, and the other was in the convective rain zone of the rainband. Both cells had echo top (30 dBZ) heights of approximately 5.5 km above sea level, with large radar reflectivity (Z h ) greater than 50 dBZ in each core. For the cell in the stratiform rain zone, polarimetric variables indicated that small raindrops predominated; differential reflectivity (Z DR ) was smaller than 1.5 dB, and the correlation coefficient (r hv ) was greater than 0.98 with large Z h (!40 dBZ). The DSD showed high number densities of small raindrops with diameters of 1-2 mm. For the other cell, polarimetric variables indicated the presence of large raindrops; Z DR greater than 1.5 dB and r hv smaller than 0.98 predominated in large Z h (!40 dBZ). The DSD for this cell showed lower number densities of raindrops with diameters of 1-2 mm and higher number densities of raindrops exceeding 3 mm. The significance of these distributions was confirmed by the Z DR and r hv for 25 cells in the stratiform rain zone and for 28 cells in the convective rain zone. It is notable that different precipitation particle distributions in convective cells were found in the stratiform and convective rain zones of a Baiu frontal rainband with common characteristics of low echo top heights and large Z h .Citation: Oue, M., H. Uyeda, and Y. Shusse (2010), Two types of precipitation particle distribution in convective cells accompanying a Baiu frontal rainband around Okinawa Island, Japan,

Polarimetric Radar Observation of the Melting Layer in a Convective Rainfall System during the Rainy Season over the East China Sea

“…9a). The foregoing features of vertical profiles of polarimetric radar variables have also been reported in embedded convective rainfalls in Baiu front events during the rainy season in East Asia (Shusse et al 2009;Oue et al 2010).…”

Vertical distribution of precipitation particles in Baiu frontal stratiform intense rainfall around Okinawa Island, Japan

“…Comparisons with Oue et al . [, ] suggest that the stratiform precipitation in this study had DSDs with higher number concentrations of smaller raindrops than observed previously in convective cells in a Baiu frontal convective precipitation region around Okinawa Island. The DSDs also suggest the presence of larger raindrops than observed previously in convective cells embedded in a Baiu frontal stratiform precipitation region around Okinawa Island.…”

“…The characteristics of the raindrop size distribution (DSD) around Okinawa Island have been the focus of several studies [ Bringi et al ., ; Shusse et al ., ; Oue et al ., , ]. Shusse et al .…”

“…Oue et al . [, ] reported large and small raindrops in convective cells embedded in convective and stratiform precipitation regions, respectively, over the Baiu front. On the other hand, the DSDs of stratiform areas associated with squall lines in the tropics and continental precipitation systems were reported to have lower number concentrations of larger raindrops than the DSDs of convective areas [e.g., Tokay and Short , ; Bringi et al ., ].…”

Statistical Characteristics of Raindrop Size Distribution in the Meiyu Season Observed in Eastern China

“…The Meiyu-Baiu front brings heavy rainfall in east China, mainly in the Yangtze-Huaihe River basin, and over the southern part of Japan. In recent years, authors have studied the characteristics of DSDs during the Baiu period in Japan (e.g., Harimaya 2003, 2005;Shusse et al 2009;Oue et al 2010); however, not much is known about the DSDs in the Meiyu season in China, mainly because of the lack of DSD measurements.…”