| dc.description.abstract | 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. | en_US |