Insect-Equivalent Radar Cross-Section Model Based on Field Experimental Results of Body Length and Orientation Extraction

Abstract

Migratory insects constitute a valuable component of atmospheric and terrestrial biomass, and their migratory behavior provides abundant information for insect management and ecological effect assessment. Effective monitoring of migratory insects contributes to the evaluation and forecasting of catastrophic migration events, such as pest outbreaks. With a large-scale monitoring technique using S-band weather radar, the insect density is estimated based on the linear relationship between radar reflectivity and the average radar cross-section (RCS) of the insects. However, the average RCS model neglects the morphological and observation parameters of the insects, which reduces the estimation accuracy. In this paper, we established an insect-equivalent RCS model based on the joint probability distribution of “body length–incident angle”. Then, we observed and extracted the morphological and observational parameters of the migratory insects by conducting a 69-day field experiment, using a Ku-band fully polarimetric entomological radar, in Dongying, Shandong Province, China. Finally, combined with the experimental results and the simulated scattering characteristics of individual insects with different body lengths, the typical insect-equivalent RCS model was established. The RCS of the model fluctuates between 0.233 mm2 and 0.514 mm2, with different incident angles. Our results lay a data foundation for the quantitative analysis of insects by weather radar.

Analysis of the Influence of Polarization Measurement Errors on the Parameter and Characteristics Measurement of the Fully Polarized Entomological Radar

“…s hh s hv s vh s vv (11) and the superscript T represents the transpose of the matrix. By Equation (7), it can be seen that the target measured SM in the presence of systematic polarization measurement errors can be expressed as…”

“…Migratory pests lead to a significant reduction in food production every year [4]. In order to study the migration patterns of insects and pest warning, the migration routes, biomass, and species of migratory insects have been studied by a multitude of researchers [5][6][7].…”

Quantification of Migration Birds Based on Polarimetric Weather Radar

“…The spatial resolution of weather radar is low, and there are multiple birds in one range gate. This is a typical volume scattering model [15,16]. Suppose that the distribution of the angle between the target's axis and weather radar line-of-sight is p(θ), and the fluctuation model of the radar cross sectional area (RCS) of birds at different horizontal angles is rcs(θ), representing the ratio of RCS of different azimuths to RCS at an azimuth of θ = 0.…”

“…The key to retrieving the bird number is to build a function, i.e., obtaining the average RCS of birds. Bird average RCS can be estimated by means of simulation [15,17,18] or actual measurement [19] in a microwave darkroom, but it requires a lot of effort to build bird geometric models or acquire experimental data in a darkroom. In addition, the number of samples is limited, leading to a lack of representativeness.…”