Optical turbulence simulations over the Tibetan Plateau based on a single-column model with high-order closure

Area of Science:

• Atmospheric physics and turbulence modeling
• Optical astronomy and adaptive optics
• Numerical weather prediction

Background:

• Optical turbulence degrades ground-based telescope resolution and impacts astronomical observations.
• Accurate forecasting of optical turbulence (Cn2) is essential for optimizing telescope scheduling and adaptive optics systems.
• Existing methods rely on mesoscale models with simplified turbulence closure, assuming quasi-steady-state atmospheric conditions.

Purpose of the Study:

• To develop and evaluate a novel approach for forecasting optical turbulence (Cn2) profiles.
• To utilize a single-column model (CLUBB) with higher-order turbulence closure for improved parameterization.
• To assess the model's performance against field measurements and compare it with existing methods.

Main Methods:

• Implemented a new Cn2 parameterization scheme within the single-column framework of the Coupled Large Eddy Simulation Model (CLUBB).
• Incorporated a more complete physical process in the parameterization, avoiding steady-state assumptions.
• Validated the model using field campaign data from the Da Qaidam site on the Tibetan Plateau, comparing with sounding measurements.

Main Results:

• The model successfully captured typical Cn2 profile evolution under convective conditions.
• Achieved a bias of 0.01 and RMSE of 0.31 for atmospheric seeing without calibration, outperforming prior mesoscale models.
• Demonstrated statistical agreement between simulations and measurements, with observed improvements over existing Cn2 algorithms.

Conclusions:

• The proposed boundary layer parameterization in the CLUBB model offers a promising approach for accurate optical turbulence forecasting.
• This method provides a more physically complete representation compared to traditional mesoscale models.
• The approach holds potential for advancing 3D optical turbulence forecasting when coupled with mesoscale models.