Saito Research Group - TAMUdust2020

1. General

The TAMUdust2020 is a comprehensive, flexible, and user-friendly database for optical properties of dust aerosol and volcanic ash particles. Various ensembles of 20 irregular hexahedral particle models are applied in this database. The organization of this database is described in the ReadMe file. The database consists of source codes (.f90) and data kernels, which are available from:

TAMUdust2020 Version 1.0.0 (https://doi.org/10.5281/zenodo.4711247).
The latest version of the TAMUdust2020 source codes (https://github.com/masasaito/TAMUdust2020).

Note: An erratum in the README.md file appears in the definition of the size parameter. x=2*pi*D/W is the correct definition.

Lead developer: Dr. Masanori Saito (msaito [at] uwyo.edu)

PI: Dr. Ping Yang

Reference:

1). Saito, M., P. Yang, J. Ding, and X. Liu (2021), A comprehensive database of the optical properties of irregular aerosol particles for radiative transfer simulations, J. Atmos. Sci., 78, 2089–2111.

2). Saito, M., and P. Yang (2021), Advanced bulk optical models linking the backscattering and microphysical properties of mineral dust aerosol, Geophys. Res. Lett., 48, e2021GL095121.

2. History

(MM/DD/YYYY) (Author) (Note)

06/01/2018 Masa Saito Project initiated.

03/01/2019 Masa Saito Extended the applicability from 3 lidar wavelengths to shortwave (0.2 to 4 micron).

03/16/2020 Masa Saito Sphericity variation is considered.

05/01/2020 Masa Saito Extended the applicability from shortwave to the entire wavelengths (0.2-200 micron).

07/30/2020 Masa Saito The database Version 0.9 has been completed.

09/30/2020 Masa Saito The database Version 0.9.9 has been completed (This will automatically be Version 1.0 after publication)

10/07/2020 Masa Saito Source code published.

04/22/2021 Masa Saito Version 1.0.0 released.

10/11/2021 Masa Saito Improved multi-dimensional linear interpolation.

10/22/2021 Masa Saito Required memory substantially reduced.

12/14/2021 Masa Saito Released as Version 1.1.0

3. Overview of the Database

The TAMUdust2020 database comprehensively covers the ranges of wavelengths, particle sizes, particle morphologies, and the refractive indices as follows:

Size parameter (x = kD): Rayleigh regime to 11800 (SW); Rayleigh regime to 1450 (LW)
Sphericity: 0.695 to 0.785
Real part of the refractive index: 1.37-1.7 (SW); 0.4-3.2 (LW)
Imaginary part of the refractive index: 0.0001-0.1 (SW); 0.001-4.0 (LW)

As long as the size parameter and the refractive index covers, the TAMUdust2020 database is applicable to any of ranges in sizes and wavelengths. For example, the database with SW kernel covers the particle maximum diameter up to 1000 µm at a wavelength of 532 nm (lidar wavelength); and the database with a combination of both SW and LW kernels covers particle maximum diameters up to 375 µm at wavelengths from 0.2 µm through 200 µm.

The particle shape is assumed to be an ensemble of 20 irregular hexahedral particles (Fig. 1). The mixing ratio of each irregular hexahedral particle is determined by a specified sphericity. In general, smaller sphericity indicates a higher aspect ratio and irregular particle, while higher sphericity indicates a more compacted particle shape.

Figure 1. An illustration of the ensemble irregular hexahedral particle model.

4. Structure & Usage

The structure and user interface of the TAMUdust2020 database is illustrated in Fig. 2. A practically useful feature of the TAMUdust2020 database is flexibility for user’s needs. To obtain the single-scattering properties of a user-defined aerosol model, the following two commands are available:

tamudust2020single :: Create the single-scattering properties of a user-defined aerosol particle.
tamudust2020create :: Create the single-scattering property database of user-defined aerosol optical property model.

4.1 tamudust2020single

A user prepare an input file that specifies a configuration of a data kernel, and then type the following command:

$ ./tamudust2020single {input_file} {max_diameter} {wavelength} {mr} {mi} {sphericity} {output_path}

4.2 tamudust2020create

A user prepare the following input to create a single-scattering property database of a user-defined aerosol model:

wavelength bin file
maximum diameter bin file
spectrally dependent refractive index file
a comprehensive input file where a user specifies size-invariant sphericity

Then, type the following command:

$ ./tamudust2020create {input_file}

Figure 2. The basic logic flow of the TAMUdust2020 database and the generation process of the single-scattering property database of a user-defined customized aerosol model. Adapted from Saito et al. (2021). For more information, please read the ReadMe file in the TAMUdust2020 database.

5. Data Availability & Requirements

The lead developer, Dr. Masanori Saito encourages the research community to utilize the TAMUdust2020 database for various aerosol studies. The only requirement in regards to utilizing scattering properties generated from the database for research is to acknowledge our contribution in your papers/presentations by:

cite Saito et al. (2021) in a relevant section of the main text.
add the following description in Acknowledgement section or Data Availability section: "The scattering properties are obtained from the TAMUdust2020 database (https://zenodo.org/record/4711247)."

Any portion of the database is allowed to redistribute as part of some existing package (e.g., a radiative transfer model) if the following requirements are satisfied:

specify the reference (Saito et al., 2021) in a user guide of the package to be redistributed.
add brief descriptions in the package to let users recognize that the data originate from the TAMUdust2020 and let them cite Saito et al. (2021) when they use the data through the redistributed package for their research.

6. Frequently Asked Questions

When I tried to run the database, it shows an error message (Error code = 2) and the code stopped. What is the issue?

Check the paths to the data kernels. In ./tables/SW and ./tables/LW directories, there should have two binary files named as TAMUdust2020isca.bin and TAMUdust2020PMat.bin, which can be obtained from a separate compressed file in the database.

Which degree of sphericity is recommended for mineral dust and volcanic ash particles?

At this point, we recommend 0.7 or some value in a range 0.695-0.715 according to validations in the bulk phase matrix elements of these particles based on laboratory measurements. For folks who seek observationally constrained degree of sphericity of dust aerosol, please read Saito and Yang (2021) GRL paper.

What particle size definition is used in the database?

The TAMUdust2020 Version 1.0.0 uses "maximum diameter" (defined as a diameter of a circumscribed sphere of a particle) as the size definition. In Vesion 1.1.0 provdes three options in the size definitions: maximum diameter, projected-area-equivalent sphere diameter, and volume-equivalent sphere diameter.

7. Developer's Log (v1.0.0 or above)

Version 1.2.0 (Planned)

Seamless user interface for both SW and LW kernels

Version 1.1.0 (12/14/2021)

Implement various size definitions (Maximum diameter, projected-area equivalent sphere diameter, and volume-equivalent sphere diameter).
Implement a separate module structure.
Improved interpolation scheme.
Cleaning codes and reducing memory requirements.

Version 1.0.0 (04/22/2021)

Source codes and data kernels are published at Zenodo.org.