Proceedings with Extended Abstracts (single PDF file) - Radio ...

Disdrometer has collected 5639, 1584, and 9421 minutes of 1 min. samples of DSDduring the years 1997, 1998 and 1999 respectively. The rain parameters, median volumediameter (D 0 ), rainrate (R) and Reflectivity factor (Z) have been estimated from the DSDusing the standard method (Rao et al. 2002, Reddy et al., 2003). Further, the gammaparameters (shape, slope and the intercept) are derived using the method proposed by Kozuand Nakamura (1991). The data has been grouped into 3 categories based on the magnitudeof R. Monthly variation of D 0 and N 0 has been plotted in Figure 2 (a) and (b), respectively,for all the groups. It is clearly evident from the Figure that D 0 values are higher in SWmonsoon season than in NE monsoon season. On the other hand, obviously, the N 0 shows anopposite trend with low values in SW monsoon and high values in NE monsoon. Theobserved trend is similar for all the groups.The estimated R and Z are used to derive the Z-R relationships, which is in the formof Z= 10 a R b , where a is the intercept and b is the slope of the best-fit line on log Z and logRplot. September and December months are chosen to represent SW and NE monsoonseasons. Figure 3(a)-(d) shows the scatter plots of dBR Vs dBZ for all the samples collectedin September and December months for 1997, 1999, 2000 and 2001.Figure 3. Scatter plots of dBR vs dBZ for samples collected in September and December during (a) 1997,(b) 1999, (c) 2000 and (d) 2001.It also includes, straight line fitted to the data, the correlation coefficient, the slopeand the intercept. Further, it can be noted from the Figure that the intercept and the slopes aredifferent for September and December. The variation of a and b against the month are shownin Figure 4. It can be seen from the figure that, the variation of the intercept is similar to thatof D 0 with high values in SW monsoon season and low values in NE monsoon season. Onthe other hand, the variation of b is not so significant.320