||The formation mechanism and vertical thermal structure of stratiform and convective precipitation are different. It affects not only the characteristics of drop size distribution (DSD), but also the parameterization of cloud model. The DSD can be used to determine rainfall integer parameters including rainfall rate, liquid water content, and reflectivity factor, etc. This study used DSD data collected with five Joss-Waldvogel disdrometers (i.e. NCU, Feitsui, Nankang, Suiman, Shiyun), and a 2D-Video disdrometer in NCU, to investigate heavy rain events occurred during 2005 to 2006. And then use the intercept parameter N0 and rainfall rate to classify precipitation type into two categories: stratiform and convective.|
The normalized DSDs are distinct difference between stratiform and convective. The shape of DSD in stratiform is near exponential, and have more small raindrops, but there are less small raindrops in convective. At the same rainfall rate, stratiform has larger drop spectrum than convective. The DSD parameters and integral rainfall parameters are also different in these two rainfall types. Overall, the parameters of μ, Λ, N0, Nw, and Dm in convective type rainfall are greater then those of stratiform. Having compared Nw-Dm of stratiform and convective precipitation with the statistic results of Bringi et al. (2003), we found that the pattern of stratiform in northern Taiwan agreed well. The pattern of convective type is near the maritime-like cluster, but when rainfall rate is greater than 20 mm/hr, the pattern is between maritime and continental-like cluster. After normalized, the b parameters of Z-R relation can be defined as constant, and parameter A almost has one-to-one relation with rainfall rate R.
Case study on Typhoon and Mei-yu, we found that no matter what type it is, the variation of parameters (i.e. μ, Λ, Dm , Nw) are similar when rainfall are classified to stratiform and convective types. In convective precipitation, the variation of parameters of Typhoon case is greater than Mei-yu case. However, the variations of stratiform parameters in both cases are stable.
張偉裕, 2002: 利用雨滴譜儀分析雨滴粒徑分布(納莉颱風個案), 國立中央大學碩士論文，95頁。
Atlas, D., and C. W. Ulbrich, 1977: Path-and area-integrated rainfall measurement by microwave attenuation in the 1-3 cm band. J. Appl. Meteor., 16, 1322-1331.
Brands, E. A., G. Zhang, and J. Vivekanandan, 2003: An evaluation of a drop distribution-based polarimetric radar rainfall estimator. J. Appl. Meteor., 42, 652-660.
Bringi, V. N.,V. Chandrasekar, J. Hubbert, E. Gorgucci, W. L. Randeu, and M. Schoenhuber, 2003: Raindrop size distribution in different climatic regime from disdrometer and dual-polarized radar analysis. J. Atmos. Sic., 60, 354-365.
Chen, C. S., and Y. L. Chen, 2003: The rainfall characteristics of Taiwan. Mon. Wea. Rev., 131, 1323-1341.
Cifelli, R., C. R. Williams, D. K. Rajopadhyaya, S. K. Avery, K. S. Gage, and P. T. May, 2000: Drop-size distribution characteristics in tropical mesoscale convective systems. J. Appl. Meteor., 39, 760-777.
Gamache, J. F., and R. A. Houze, 1982: Mesoscale air motions associated with a tropical squall line. Mon. Wea. Rev., 110, 118-135.
Gunn, R. and G. D. Kinzer, 1949: The terminal velocity of fall for droplets in stagnant air. J. Meter., 6, 243-248.
Huggel, A., W. Schmid, and A. Waldvogel, 1996: Raindrop size distributions and the radar bright band. J. Appl. Meteor., 35, 1688-1701.
Johnson, R. H., and P. J. Hamilton, 1988: The relationship of surface features to the precipitation and air flow structure of an intense midlatitude squall line. Mon. Wea. Rev., 116, 1444-1472.
Jorgensen, D. P., and P. T. Willis, 1982: A Z-R relationship for hurricanes. J. Appl. Meteor. 21, 356-366.
Kozu, T., and K. Nakamura, 1991: Rainfall parameter estimation form dual-radar measurements combining reflectivity profile and path-integrated attenuation. J. Atmos. Oceanic Technol., 8, 259-270.
Maki, M., T. D. Keenan, Y. Sasaki, and K. Nakamura, 2001: Characteristics of the raindrop size distribution in tropical continental squall lines observed in Darwin, Australia. J. Appl. Meteor., 40, 1939-1412.
Marshall, J. S., and W. McK. Palmer, 1948: The distribution of raindrops with size. J. Meteor., 5, 165-166.
Testud J., S. Qury, R. A. Black, P. Amayenc, and X. Dou, 2001: The concept of “Normalized” distribution to describe raindrop spectra: A tool for cloud physics and cloud remote sensing. J. Appl. Meteor., 40, 1118-1140.
Tokay A., and D. A. Short, 1996: Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds. J. Appl. Meteor., 35, 355-371.
____, A. Kruger, and W. F. Krajewski, 2001: Comparison of drop size distribution measurements by impact and optical disdrometers. J. Appl. Meteor. 40, 2083-2097.
____, D. A. Short, C. R. Williams, W. L. Ecklund, K. S. Gage, 1999: Tropical rainfall associated with convective and stratiform clouds: Intercomparison of disdrometer and profiler measurements. J. Appl. Meteor. 38, 302-320.
Ulbrich, C. W, 1983: Natural variations in the analytical form of the raindrop size distribution. J. Climate Appl. Meteor., 22, 1764-1775.
____, and D. Atlas, 1998: Rainfall microphysics and radar properties: Analysis methods for size spectra. J. Appl. Meteor. 37, 912-923.
Vivekanandan, J., G.. Zhang, and E. Brandes, 2004: Polarmetric radar estimators based on a constrained gamma drop size distribution model. J. Appl. Meteor. 43, 217-230.
Waldvogel, A., 1974: The N0 jump of raindrop spectra. J. Atmos. Sci., 31, 1067-1078.
Williams, C. R., W. L. Ecklund, and K. S. Gage, 1995: Classification of precipitation clouds in the tropics using 915-MHz wind profilers. J. Atmos. Oceanic Technol., 12, 996-1012.