Weather radars enable the monitoring of airborne insects over spatial scales ranging from hundreds to thousands of kilometers. Quantitative information on migration intensity and spatial distribution can be obtained from weather radar observations. However, insect biological characteristics cannot be directly retrieved from weather radar, which limits species identification. Among the parameters associated with insect species, body length describes an important aspect of individual morphological characteristics. In this study, we propose a method for estimating the mean body length of airborne insect populations based on S-band polarimetric weather radar observations. A theoretical relationship is established between mean body length, insect number density, and the specific differential phase, which is defined as the range derivative of the phase difference between horizontally and vertically polarized radar signals. Electromagnetic simulations are conducted to analyze the relationship between specific differential phase and mean body length under known number density. Furthermore, the method is validated using joint observations from weather radar and entomological radar. The experimental results show that, for insects with body lengths ranging from 5 to 25 mm, the proposed method achieves a mean absolute percentage error (MAPE) of 10.75% in body length estimation, demonstrating its capability to accurately estimate the mean body length of insect populations. This study provides data support for species identification in current weather-radar-based insect monitoring and shows promise for applications in large-scale pest early warning, species classification, and ecological dynamics research.
Cui et al. (Sat,) studied this question.