Characteristics of Rain Integral Parameters during Tropical Convective, Transition, and Stratiform Rain at Gadanki and Its Application in Rain Retrieval

Abstract

In the present study the characteristics of rain integral parameters during tropical convective (C), transition (T), and stratiform (S) types of rain are studied with the help of Joss-Waldvogel disdrometer (JWD), L-band, and very-high-frequency wind profilers at Gadanki (13.58N, 79.208E). The classifications of three regimes are made with the help of an L-band wind profiler. For rain rate R , 10 mm h 21 larger drops are found in S type of rain relative to C and T rain, and for R $ 10 mm h 21 larger drops are found in convective rain. Empirical relations are developed for D m -R, D m -Z, N 0 * -R, Z-R, and Z/D m -R by fitting the power-law equations. Event to event, no systematic variation of the coefficients and exponents could be found for Z-R and Z/D m -R relations during the three types of rain. Overall, the C and S events are found to be number controlled, and T events are size controlled. During C type of rain, bigger mean raindrops are found during the presence of strong updrafts. During S type of rain, bigger mean raindrops are found to be associated with the higher mean thickness of the bright band and strong velocity gradient. For each of the developed empirical relations, the correlation coefficients are found in the order of T . C . S rain. During the three types of rain, correlations are found in the order of Z/D m -R . Z-R . D m -Z . D m -R. Significant improvement is observed in rain retrieval by using the Z/D m -R relation relative to the conventional Z-R relation. By utilizing the Z/D m -R relations, the root-mean-square error was reduced by 19%-46%.

Microphysics of clouds and rain over the Western Ghat

“…The DSDs characterized by size-controlled processes provide a limiting case for valid range of shape factor μ [Steiner et al, 2004]. From wind profiler measurements and MRR, the CCB processes are found to dominate among the raindrops during the tropical stratiform rain [Kirankumar et al, 2008;Sharma et al, 2009;Konwar et al, 2012a]. Although we do not have simultaneous X band radar observations of the storms under discussion, limited observations of the stratiform precipitating system for another day indicates presence of liquid hydrometeors below the melting layer ( Figure S1).…”

“…The scatter plots of Z-R relationships over Atlas et al, 1999;Ulbrich and Atlas, 2007;Rao et al, 2001;Sharma et al, 2009]. However, greater than unity value of the exponent suggest that rain processes are dominated by size-controlled processes.…”

“…The coefficient "a" infers presence of smaller or bigger raindrops while the exponent "b" infers microphysical processes. Large exponent value (b > 1) characterizes size or mixed controlled case (i.e., CC) while linear Z-R relationship (b~1) is associated with number controlled case (i.e., CCB) for steady and statistically homogeneous or equilibrium rainfall [Atlas et al, 1999;Atlas and Williams, 2003;Steiner et al, 2004;Sharma et al, 2009].…”

Tropical Rain Classification and Estimation of Rain From Z-R (Reflectivity-Rain Rate) Relationships

“…The A coefficients of the Z-R relations obtained for the nine rain events have a mean value of 288.63 with a standard deviation of 88.95 for stratiform rain. But for the convective rain, the A coefficients of the Z-R relations Several studies [25,26] have shown how the DSD, and therefore the Z-R relationship, varies geographically, with rainfall intensity. It is also stated in [25] that the coefficient A is smaller for stratiform rain and increases for increasing convective activity, while b behaves in the opposite manner (smaller for convective rain and larger for stratiform systems).…”

“…But for the convective rain, the A coefficients of the Z-R relations Several studies [25,26] have shown how the DSD, and therefore the Z-R relationship, varies geographically, with rainfall intensity. It is also stated in [25] that the coefficient A is smaller for stratiform rain and increases for increasing convective activity, while b behaves in the opposite manner (smaller for convective rain and larger for stratiform systems). As expected, the coefficient A is larger for the tropical convective rain (Singapore) followed by the stratiform stage because of the presence of larger drops in these stages.…”