Radar and Lidar scattering lookup tables for atmospheric hydrometeors using a T-Matrix method and a Mie theory

Overview

The database includes text files containing the scattering amplitude matrices for single spherical/nonspherical particles for radar and lidar. They are the lookup tables used for calculating radar and lidar observables in the Cloud-Resolving Radar Simulator (Oue et al. 2020). The radar scattering properties were calculated for several hydrometeor categories using a T-matrix method proposed by Mishchenko (2000) accounting for incident angles, scattering direction (forward and backward), polarimetry (horizontally (H) and vertically (V) polarized waves), particle aspect ratio, phase (liquid or ice), bulk density, temperature, particle size, and radar frequency.  The lidar scattering properties at a vertical incidence were calculated for spherical liquid or ice particles using the BHMIE Mie code (Bohrean and Hyffman,1998) accounting for lidar wavelength, temperature, and bulk density. The hydrometeor categories are commonly used for cloud resolving models employing bulk microphysical schemes (e.g., cloud, rain, ice cloud, snow aggregates, and graupel). Detailed descriptions are also available in the CR-SIM user guide (https://github.com/marikooue/CR-SIM/releases/tag/crsim-v3.34).

Data structure

The data files are arranged and zipped every hydrometeor types. The names of the tar-zipped directories under the top directory LLUT3 represents the hydrometer type.
For lidar scattering, the following directories are included:
ceilo: Ceilometer lidar backscatter properties at a wavelength of 905 nm
mpl: Micropulse lidar (MPL) backscatter properties at wavelengths of 353 and 532 nm

For radar scattering, the following hydrometer types are included:
cloud: Radar scattering for liquid cloud droplets (spherical shape)
raina: Radar scattering for raindrops with the aspect ratio model proposed by Andsager et al. (1999)
rainb: Radar scattering for raindrops with the aspect ratio model proposed by Brandes et al (2002)
ice_ar0.90: Radar scattering for cloud ice with an aspect ratio of 0.9
ice_ar0.20: Radar scattering for cloud ice with an aspect ratio of 0.2
smallice: Radar scattering for spherical cloud ice particles
snow_ar0.60: Radar scattering for snowflakes with an aspect ratio of 0.6
graupel_ar0.60: Radar scattering for graupel particles with an aspect ratio of 0.6
graupel_ar0.80: Radar scattering for graupel particles with an aspect ratio of 0.8
graupel: Radar scattering for spherical graupel particles
gh_ryzh: Radar scattering for graupel particles with the graupel aspect ratio model proposed by Ryzhkov et al (2011)
unrimedice_ar0.40: Radar scattering for unrimed ice particles with an aspect ratio of 0.4
unrimedice_ar0.60: Radar scattering for unrimed ice particles with an aspect ratio of 0.6
unrimedice_ar0.80: Radar scattering for unrimed ice particles with an aspect ratio of 0.8
unrimedice: Radar scattering for spherical unrimed ice particles
partrimedice_ar0.40: Radar scattering for partially rimed ice particles with an aspect ratio of 0.4
partrimedice_ar0.60: Radar scattering for partially rimed ice particles with an aspect ratio of 0.6
partrimedice_ar0.80: Radar scattering for partially rimed ice particles with an aspect ratio of 0.8
partrimedice: Radar scattering for partially rimed spherical ice particles 

The file name convention 

For lidar scattering data, each file name has the following format:
[hydrometeor type]_[instrument name]_ [wavelength in nm]_[phase ID]_d[bulk density in kg m-3].dat
The hydrometeor type shows: 1) ‘cld’ for liquid cloud droplets, and 2) ‘ice’ for ice particles. The phase ID shows: 1) ‘p25’ for ceilometer liquid cloud, 2) ‘p20’ for MPL lidar liquid cloud, and 3) ‘m30’ for MPL lidar ice. 

For radar scattering data, each file name has the following format.
[hydrometeor type]_fr[frequency in GHz]GHz_t[temperature in K]_rho[bulk density in kg m-3]_el[elevation angle in degree].dat
The hydrometeor type follows the directory name presented above.

Format of the data files

Line 1: Wavelength in mm
Line 2: Temperature in K
Line 3: Refractive index (real and imaginary)
Line 4: Number of radii calculated and number of elevation angles
Line 6: Incident angle and scattered angle in degrees
Line 7: Radius in mm and aspect ratio
Line 8: Forward scattering amplitude for co-polarization VV and HH (complex number)
Line 9: Backward scattering amplitude for co- and cross polarizations VV, VH, HV, HH (complex number)   
Line 10 to the end of file: Repeat Line 7 to Line 9 with different radii until the maximum radius.