Intercomparison of flux, gradient, and variance-based optical turbulence ($C_n^2$) parameterizations

References

This repository accompanies the work published in Applied Optics as

Pierzyna, M., Hartogensis, O., Basu, S., and Saathof R. "Intercomparison of flux, gradient, and variance-based optical turbulence ($C_n^2$) parameterizations." Applied Optics, vol. 63, no. 16, 2024, pp. E107-E119. https://doi.org/10.1364/AO.519942

The simulated and observed data discussed in our article and utilized by the plotting functions of this repository (eval) are published on Zenodo

Pierzyna, M. "Dataset: Intercomparison of flux, gradient, and variance-based optical turbulence ($C_n^2$) parameterizations." In Applied Optics. Zenodo. https://doi.org/10.5281/zenodo.10966120.

WRF Simulations

All files required to run the Weather Research and Forecasting (WRF) model are contained in the simulation directory of this repository. The directory contains subdirectories for each test case discussed in the manuscript. Each subdirectory contains two files:

• namelist.wps: Settings for the WRF Preprocessing System (WPS)
• namelist.input: Settings for WRF. Importantly, the configuration of the phyiscs schemes is configured here.

The myoutfields.txt ensures that all relevant variables written to the output files when WRF is running. By default, WRF does not output all variables required for the variance-based parameterization such as TSQ (potential temperature variance) or QKE (twice turbulent kinetic energy). This file needs to be placed in the same directory as namelist.input.

Post-processing: $C_n^2$ estimation

The codes to post-process the WRF simulations and estimated $C_n^2$ are contained in the post_proc directory of this repository.

Post-processing requires two steps, which are run by executing the step_XX_*.sh batch files in order:

1. step_1_extract_variables.sh: Extract one vertical cross-section of interest from the full WRF output through horizontal interpolation (see extract_variables.py).
2. step_2a_post_proc_wrf.sh: Run various post-processing steps such as interpolating the WRF pressure levels to a common altitude level, compute stability parameters, or estimating $C_T^2$ and $C_n^2$ (see post_proc_wrf.py and ct2_cn2_estimation.py)

The step_2b_post_proc_obs_cn2.py needs to be run to estimate $C_T^2$ and $C_n^2$ from data observed at the CESAR site, which are available through the KNMI data platform (KDP, https://dataplatform.knmi.nl/dataset/?q=Cesar)

Plotting and evaluation

The codes to assess the accuracy of the $C_n^2$ estimates quantitatively (scores) and qualitatively (plots) are contained in the eval directory of this repository.