The Characteristics of Rain Drop Size Distributions Using a POSS in Busan Area

다국어 초록 (Multilingual Abstract)

The relationship between radar reflectivity factor (Z) and rainrate (R) has been largely varied with the characteristics of precipitation and effects of topography. In this study, drop size distribution (DSD) of precipitation by a Precipitation Occurrence Sensor System (POSS) was accomplished from 2001 to 2002 year to obtain more accurate Z-R relationship and compared with Marshall and Palmer (M-P) distribution in Busan area. As a result, The values of DSDs by POSS and M-P distribution were not well coincided with around diameter 2 mm size. Well-fitting seasonal DSDs were obtained at the ranges of N0 (701～8,044) and (1.9～2.7) using least squares method. In gamma distribution at each rainrate with 6 categories monthly N0(m-3mm-1), Λ(mm-1) and m were varied at 59.0～5.4×104, 0.01～2.2, and -3.9～0.4 in 2001 as compared with 6.74×102～2.13×104, 0.2～1.3, and -3.8～-1.9 in 2002. The distribution of raindrops number concentration (N(D)) with size by POSS was represented as an untruncated exponential function at the rainrates between 1 to 10 mm/h in Busan and it had good agreement at all ranges of raindrops as compared with theoretical M-P's, relatively.

국문 초록 (Abstract)

레이더 반사도와 강우강도 (Z-R) 관계식은 강수입자의 직경 함수로써, 지역이나 강수의 특성에 따라 변동성이 크다. 본 연구에서는 부산지역 강수의 정확한 Z-R 관계식을 산출하기 위하여 강수입자분석기의 일종인 Precipitation Occurrence Sensor System (POSS)을 이용하여 2001년과 2002년의 부산지방 강수의 직경분포 특성을 알아보았으며, Marshall and Palmer (M-P)가 제안한 분포와 비교 하였다. 그 결과, 강수직경이 2 mm 전후에서 관측값 보다 이론값인 M-P분포에서 각각 과소, 과대평가 되었으며, 이들 오차를 줄이기 위하여 최소자승법을 이용한 매개변수 N0(701~8,044 범위)와 (1.9~2.7 범위)값을 구하여 부산지방의 계절별 적절한 강수입자의 수농도를 구하였다. 또한 강우강도별 직경분포 특성을 파악하기 위하여 강우강도별로 6개의 범주를 만들어 Gamma 모델을 이용한 세가지 매개변수를 산출하였으며, 그결과, 2001년에는 Gamma 매개변수인 N0가 59.0에서 5.4×104, 는 0.01에서 2.2, m값은 -3.9에서 0.4의 분포를 가졌다. 2002년에는 각각 6.74×102에서 2.13×104, 0.2에서 1.3, 그리고 -3.8에서 -1.9의 범위를 나타내었다. 관측기간중 계절별 강우강도가 1~10 mm/h에서 POSS의 강수입경별 수농도분포가 일정한 형태의 지수분포를 가졌으며, 이론적 M-P분포에 비해 모든 강수입경 영역에서 Gamma분포와 유사한 수농도 분포를 보였다.

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