ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 26, NO. 2, 2009, 211–221 Comparison of the Bright Band Characteristics Measured by Micro Rain Radar (MRR) at a Mountain and a Coastal Site in South Korea Joo-Wan CHA 1,2 , Ki-Ho CHANG 2 , Seong Soo YUM ∗ 1 , and Young-Jean CHOI 2 1 Department of Atmospheric Sciences, Yonsei University, Korea 2 Global Environment System Research Laboratory NIMR/KMA, Korea (Received 1 November 2007; revised 30 October 2008) ABSTRACT Data from a long term measurement of Micro Rain Radar (MRR) at a mountain site (Daegwallyeong, DG, one year period of 2005) and a coastal site (Haenam, HN, three years 2004–2006) in South Korea were analyzed to compare the MRR measured bright band characteristics of stratiform precipitation at the two sites. On average, the bright band was somewhat thicker and the sharpness (average gradient of reflectivity above and below the reflectivity peak) was slightly weaker at DG, compared to those values at HN. The peak reflectivity itself was twice as strong and the relative location of the peak reflectivity within the bright band was higher at HN than at DG. Importantly, the variability of these values was much larger at HN than at DG. The key parameter to cause these differences is suggested to be the difference of the snow particle densities at the two sites, which is related to the degree of riming. Therefore, it is speculated that the cloud microphysical processes at HN may have varied significantly from un-rimed snow growth, producing low density snow particles, to the riming of higher density particles, while snow particle growth at DG was more consistently affected by the riming process, and therefore high density snow particles. Forced uplifting of cloudy air over the mountain area around DG might have resulted in an orographic supercooling effect that led to the enhanced riming of supercooled cloud drops. Key words: Micro Rain Radar, bright band thickness and sharpness, cloud microphysical processes, local characteristics Citation: Cha, J.-W., K.-H. Chang, S. S. Yum, and Y.-J. Choi, 2009: Comparison of the bright band characteristics measured by Micro Rain Radar (MRR) at a mountain and a coastal site in South Korea. Adv. Atmos. Sci., 26(2), 211–221, doi: 10.1007/s00376-009-0211-0. 1. Introduction A bright band is the enhanced radar echo area that is associated with the melting of hydrometeors in stratiform precipitation. The top of the bright band can be considered as the melting level (or freez- ing height), commonly accepted as the altitude of the 0 ◦ C isotherm (Glickman, 2000). The bright band of- ten leads to an overestimation of precipitation inten- sity (Rico-Ramirez et al., 2005) and several algorithms have been proposed to correct the effect of the bright band (e.g., Song and Marwitz, 1989; Kitchen et al., 1994; Hardaker et al., 1995; Gray et al., 2002; Neiman et al., 2002). The characteristics of the bright band may reveal important cloud microphysical processes. Fabry and Zawadzki (1995) reported that the mixture of ice, air, and water leads to a greater increase in the radar re- flectivity than that expected from the change from ice to water. They suggest several other factors that con- tribute to this bright band phenomenon. One such factor is the distribution of water within the parti- cle, so called the density effect. That is, the distri- bution of melted water within the snow particle will appreciably affect the reflectivity value. Zawadzki et al. (2005) focused more on the density effect and pro- posed a bright band model, showing that the difference between the peak reflectivity and the snow reflectivity ∗ Corresponding author: Seong Soo YUM, ssyum@yonsei.ac.kr