A Set of Orientation-averaged Single-Scattering Properties of Nonspherical Ice Particles computed with MIDAS and DDSCAT

We evaluate several high-order quadrature schemes for accuracy and efficacy in obtaining orientation-averaged single-scattering properties (SSPs). We use the highly efficient MIDAS (formerly NESCoP) to perform electromagnetic scattering calculations to evaluate the gain in efficiency from these schemes. MIDAS, when combined with high-order quadrature for orientation averaging, namely Lebedev quadrature (lb) and spherical designs (sd), can be greater than three orders of magnitude more efficient in obtaining Radiative Transfer Models-ready SSPs of complex-shaped hydrometeors than existing Iterative Solver-Based Discrete Dipole Approximation (DDA) methods, with the native quadrature schemes they offer.

Here, we provide a set of simulation results and corresponding Fortran subroutines and Matlab functions, used to conduct the study detailed in the paper of the same title as the present repository/dataset. 

1) Simulations : 

Averaged_SSP_Cylinders: include MIDAS and DDSCAT simulations, with different numerical integration schemes and numbers of incident directions, used to plot the variations of the cylinder of radius  = 0.1 mm in Figure 8.

Convergence_study: include the calculations of the orientation averaged backscatter efficiency factor of all the particles of Table 1, that were used to plot Figures 9-14. The ten particles’ folders include MIDAS simulations with increasing numbers of incident directions for the integration schemes aq, sd2, and lb. Only a0012 was calculated with both DDSCAT and MIDAS. The DDSCAT folder for a0012 includes 30 total subfolders, 10 for each frequency (13.6, 35.6, and 94 GHz) 

2) Fortran subroutines:

get_trans_Receiv.f90 is the main subroutine used to compute and output the spherical coordinates (θ, Φ) of the different quadrature points from their X, Y and Z coordinates written in the subroutines (from the original dataset). Please note that the user can use the code lines of interest. A complete and operational version (with needed dependencies and modules) will be available soon in the context of the ongoing efforts to open-source MIDAS. 

efficient_spherical_tdesigns.f90 and efficient_symmetric_spherical_tdesigns.f90 (R Womersley)

sphere_design_rule.f90 (Burkardt, 2010a)

sphere_lebedev_rule.f90 (Burkardt, 2010b)

3) Matlab functions:

The included Matlab functions Plot_Cylinder_Cext_Cscat, ConvergenceStudy, and plot_MIDAS_Qid_fromSimPath are useful tools to, respectively, display the Cylinder simulations comparison of Figure 8, display the orientation-averaged backscatter efficiency factor of the ten particles of the convergence study of Table 1, as done in Figure 9 & 10, and finally display 2D and 3D plots of the backscatter efficiency factor from any MIDAS simulation folder (Figures 11-14).