Surface Microphysical Characteristics of Stratiform and Convective Rains in Metro Manila, Philippines

Date of Award

2020

Document Type

Thesis

Degree Name

Master of Science in Atmospheric Science

Department

Physics

First Advisor

James Bernard B. Simpas, PhD

Abstract

The study investigates the surface microphysical characteristics of stratiform and convective rains in Metro Manila, Philippines using the second-generation PARticle SIze VELocity (PARSIVEL2 ) disdrometer located at the Manila Observatory (14.64 °N, 121.08 °E), Quezon City, Philippines. Quality-controlled data from September 2018 to September 2019 were used to calculate the different surface integral rain parameters (IRPs) and rain drop size distributions (DSDs) for the categorized samples obtained from 81 identified rain events. The accumulated rains are largely contributed by convective samples despite the higher frequency of occurrences of stratiform types. The rain rate (R), total droplet concentration (Nt), radar reflectivity factor (Z), liquid water content (LWC), and number concentrations (N(D)) per droplet diameter generally increase as rain intensifies from stratiform to convective type. The scatterplots of mass-weighted mean diameter (Dm) and normalized intercept parameter (log10Nw) reveal the generally more maritime than continental nature of convective rains in Metro Manila. The occurrences of shallow rains characterized by high log10Nw and small-sized Dm, and local isolated thunderstorms with low log10Nw and large-sized Dm similar to that of a continental convective rain were also confirmed in the identified rain events. The mean log10Nw obtained for the two rain types in Metro Manila are closest to the log10Nw in the West Western Pacific and Maritime Continent (Indonesia), while lower than those in Southeast China (Zhuhai, Guangdong and Taoyuan, Taiwan) and highly maritime regions (Manus Island and Koror, Palau). On the other hand, the differences found between the classical Z–R relations and actual Z–R relations derived in Metro v Manila emphasize the need to calibrate the polarimetric radars in the country using actual Z–R relations. Notably, this study is anchored in the Cloud, Aerosol and Monsoon Processes Philippines Experiment’s (CAMP2Ex) weatHEr and CompoSition Monitoring (CHECSM) campaign: an intensive field campaign which seeks to understand the relationships between clouds, atmospheric composition, and radiative processes over the complex domain of Southeast Asia including the Philippines.

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