[1] Water vapor in the lower stratosphere may play significant roles in the atmospheric radiative budget and atmospheric chemistry; hence it is important to understand its transport process. The possibility of water vapor transport from the troposphere to the stratosphere by deep convection is investigated using three-dimensional, nonhydrostatic, quasi-compressible simulations of a Midwest severe thunderstorm. The results show that the breaking of gravity waves at the cloud top can cause cloud water vapor to be injected into the stratosphere in the form of plumes above a thunderstorm anvil. Meteorological satellites and aircrafts have observed such plumes previously, but the source of water vapor and the injection mechanism were not identified. The present results reveal that there are two types of plumes, anvil sheet plumes and overshooting plumes, in this injection process and that the process is diabatic. A first-order estimate of this plume transport of water vapor per day from the upper troposphere to the lower stratosphere was made assuming that all thunderstorms behave the same as the one simulated. Other trace chemicals may also be similarly transported by the same mechanism.

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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.