Raindrop size distribution (RSD) characteristics of summer and winter seasons over north Taiwan are analyzed by using long-term (~12 years) raindrop spectra from Joss-Waldvogel disdrometer located at National Central University (24°58 0 N, 121°10 0 E), Taiwan. Along with the disdrometer data, radar reflectivity mosaic from six ground-based radars, Tropical Rainfall Measuring Mission, Moderate Resolution Imaging Spectroradiometer, and ERA-Interim data sets are used to establish the dynamical and microphysical characteristics of summer and winter rainfall. Significant differences in raindrop spectra of summer and winter rainfall are noticed. Winter rainfall has a higher concentration of small drops and a lower concentration of midsize and large drops when compared to summer rainfall. RSD stratified on the basis of rain rate showed a higher mass-weighted mean diameter (D m ) and a lower normalized intercept parameter (log 10 N w ) in summer than winter. Similarly, diurnal variation of RSD showed higher D m and lower log 10 N w values in summer as compared to winter rainfall. In addition, for both seasons, the mean value of D m is higher in convective precipitation than stratiform. Radar reflectivity (Z) and rain rate (R) relations (Z = A*R b ) showed a clear demarcation between summer and winter rainfall. Higher ground temperatures, deeply extended clouds with intense convective activity in summer modified the RSD through evaporation, drop sorting, and collision-coalescence processes resulting with higher D m and lower log 10 N w values in summer as compared to winter rainfall. Plain Language SummaryThis study details about the raindrop size distribution characteristics variations between summer and winter seasons of north Taiwan using long-term (12 years) disdrometer data and the possible reasons for the raindrop size distribution variations are also detailed. -T. (2018). Raindrop size distribution characteristics of summer and winter season rainfall over north Taiwan. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.Following this introduction, a brief explanation of data and methodology used in the present study is provided in section 2. RSD variations of summer and winter rainfall are detailed in section 3 and followed by section 4, which includes the possible reasons for the RSD variations in summer and winter seasons. Conclusions drawn from the observational results are provided in section 5.

In this work, long-term (10 years) raindrop size distribution (RSD) measurements from the Joss-Waldvogel Disdrometer (JWD) installed at the National Central University (NCU) (24°58′6″N, 121°11′27″E), Taiwan, and the vertical profile of radar reflectivity were used to analyze the variations in the gamma parameters of six seasons (winter, spring, mei-yu, summer, typhoon, and autumn) and types of precipitation. The normalized gamma distribution of RSD revealed that the highest mean D m (mass-weighted average diameter) values occurred in the summer, whereas the highest mean log 10 N w (normalized intercept parameter) values were found in the winter. Furthermore, most of the rain falling at a rate of less than 20 mm h −1 occurs in Northern Taiwan. In this study, we used radar reflectivity to differentiate between convective and stratiform systems. It was revealed that the mean D m values are higher in convective systems, whereas the mean log 10 N w values are higher in stratiform systems. The structure of RSD in stratiform systems remains constant in all seasons; however, convection is similar

Abstract. Information about the raindrop size distribution (RSD) is vital for comprehending the precipitation microphysics, improving the rainfall estimation algorithms, and appraising the rainfall erosivity. Previous research has revealed that the RSD exhibits diversity with geographical location and weather type, which leads to the assessment of the region and weather-specific RSDs. Based on long-term (2004 to 2016) disdrometer measurements in northern Taiwan, this study attempts to demonstrate the RSD aspects of summer seasons that were bifurcated into two weather conditions, namely typhoon (TY) and non-typhoon (NTY) rainfall. The results show a higher concentration of small drops and a lower concentration of large-sized drops in TY compared to NTY rainfall, and this behavior persisted even after characterizing the RSDs into different rainfall rate classes. RSDs expressed in gamma parameters show higher mass-weighted mean diameter (Dm) and lower normalized intercept parameter (Nw) values in NTY than TY rainfall. Moreover, sorting these two weather conditions (TY and NTY rainfall) into stratiform and convective regimes revealed a larger Dm in NTY than in TY rainfall. The RSD empirical relations used in the valuation of rainfall rate (Z–R, Dm–R, and Nw–R) and rainfall kinetic energy (KE–R and KE–Dm) were enumerated for TY and NTY rainfall, and they exhibited profound diversity between these two weather conditions. Attributions of RSD variability between the TY and NTY rainfall to the thermodynamical and microphysical processes are elucidated with the aid of reanalysis, remote sensing, and ground-based data sets.