Drop size distribution from laboratory experiments based on single-drop fragmentation and comparison with aerial in-situ measurements

TL;DR

This study combines laboratory experiments, theoretical modeling, and in-situ measurements to analyze raindrop size distributions resulting from fragmentation, aiming to improve rainfall prediction accuracy.

Contribution

It introduces a comprehensive approach integrating lab experiments, gamma distribution modeling, and in-situ data to better understand and predict raindrop size distributions.

Findings

Laboratory and theoretical DSD closely match Marshall-Palmer predictions.

In-situ measurements validate the theoretical models across different altitudes.

Fragmentation processes significantly influence raindrop size distributions.

Abstract

Laboratory experiments and theoretical modelling are conducted to determine the raindrop size distribution (DSD) resulting from distinct fragmentation processes under various upward airstreams. Since weather radar echoes are proportional to the sixth power of the average droplet diameter, understanding the fragmentation mechanisms that lead to different breakup sizes is crucial for accurate rainfall predictions. We utilize a two-parameter gamma distribution for theoretical modelling and estimate the average droplet diameter from the theoretically obtained characteristic sizes, often treated as assumed input parameters for different rain conditions in rainfall modelling. Our experimental and theoretical findings demonstrate a close agreement with the DSD predicted by the Marshall and Palmer relationship for steady rain conditions. Additionally, in situ DSD measurements at different altitudes were obtained through research flights equipped with advanced sensors, further validating our rainfall model. This study underscores the effectiveness of laboratory-scale experiments and the critical importance of accurately characterizing DSD to enhance rainfall predictions.