Investigation of Orographic Z-R Relationships for Three Locations in India

The Z-R relationship, an empirical relationship between the radar reflectivity factor (Z) and rain rate (R) is a critical component used to convert the radar signal into precipitation estimates. However, the Z-R relationship can vary significantly between regions and even within a single region due to differences in atmospheric conditions and precipitation types. This variability can have a considerable impact on the reliability of precipitation estimates, which will be needed for the development of region-specific Z-R relationships. This study aims to develop a high-altitude tropical region-specific Z-R relation using the disdrometer data of Amlarem and Umiam LPM sites. To validate the proposed Z-R relationship $(\mathrm{Z}=183.\mathrm{R}^{14})$, rainfall estimates for the Sikkim region were validated and compared to Rosenfeld $(\mathrm{Z}=250.\mathrm{R}^{12})$ and the Z-R relationship $(\mathrm{Z}=276.\mathrm{R}^{13})$ currently used at Cherrapunji DWR. The results show that the proposed Z-R relation performed better with R² value of 0.744, followed by the currently used Z-R relationship and Rosenfeld Tropical with R² values of 0.717 and 0.679. The proposed Z-R relationship can be used to estimate the radar reflectivity factor in this location with greater precision. As a result, the proposed Z-R relation has great operational potential.