A lattice Boltzmann method to study light scattering by hydrometeors

We present lattice Boltzmann method (LBM) for simulating light scattering by hydrometeors, addressing the limitations of existing techniques. The accurate modelling of light scattering by hydrometeors, which include raindrops, hailstones, graupel, snowflakes, and ice crystals, is essential for remote sensing, climate modelling, and atmospheric studies. Current methods, such as the Finite-Difference Time-Domain (FDTD) method, are limited by computational cost and accuracy issues, particularly for larger particle sizes; for example, FDTD is generally restricted to size parameters smaller than about 20. This restriction arises from the method's need for fine grid resolution, where the number of numerical operations increases rapidly with particle size, scaling approximately with the fourth power of the size parameter. These limitations make FDTD impractical for many hydrometeor simulations, which often require larger size parameters. The T-matrix method and the Discrete Dipole Approximation (DDA) are alternative approaches, but they, too, have limitations. Therefore, a more efficient and accurate numerical method is needed to overcome these challenges. The LBM aims to overcome these limitations by exploring an alternative numerical approach; the goal is to provide a more computationally efficient and accurate approach. By addressing the computational challenges associated with existing numerical methods, this work enables more realistic and detailed simulations of light scattering by hydrometeors across a wider range of sizes and shapes. This has significant implications for improving remote sensing retrievals of cloud and precipitation properties, as well as advancing our understanding of the role of hydrometeors in the Earth's climate system.