Development of Global Integrated Turbulence Forecast System for the Republic Of Korea Air Force

Abstract

Unexpected encounters with aviation turbulence, a hazardous weather phenomenon affecting aircraft operations, can cause casualties and aircraft damage. The Republic Of Korea Air Force (ROKAF) currently provides turbulence forecast information for the East Asia/Korean Peninsula area based on the Korea Air Force-Weather and Research Forecasting (KAF-WRF) model-derived turbulence diagnostics. However, because the turbulence forecast information is not provided for the global area, operational weather forecasting support to overseas areas, whose importance is increasing under modern warfare, is limited. Accordingly, in this study, we developed the global integrated turbulence forecast system considering various turbulence generation mechanisms, called the KAF-Global Turbulence Forecast (KAF-GTF) system, based on the two global numerical weather prediction (NWP) models being currently used in operation by the weather group of the ROKAF. The ROKAF’s global NWP models are the Global Forecast System (GFS) and European Centre for Medium-Range Weather Forecasts (ECMWF), which have horizontal resolutions of 0.5°x0.5° and 0.25°x0.25°, respectively. The two global NWP model-based KAF-GTF systems are developed based on the methodology of version 3 of the Graphical Turbulence Guidance (GTG) system of Sharman and Pearson (2017) and consist of the following three steps: i) individual clear-air turbulence and mountain wave turbulence diagnostics representing various turbulence generation mechanisms are calculated using the global NWP model output, ii) the raw values of those turbulence diagnostics are converted into eddy dissipation rate (EDR), which represents the intensity of atmospheric turbulence, using the simple EDR conversion equation, and iii) KAF-GTF forecast is derived by combining the EDR-scaled turbulence diagnostics through ensemble averaging. The combination set of individual turbulence diagnostics and the EDR conversion equations used in the KAF-GTF system are applied as in GTG 3, considering that the combination set of turbulence diagnostics and their EDR conversion equations optimized for the global turbulence forecast were already constructed in the GTG3. In this study, the performance of two KAF-GTFs based on GFS and ECMWF are compared using turbulence cases reported from aircraft turbulence observation data for the evaluation, and the evaluation results will be represented in the conference. Acknowledgment: This research was funded by the Republic Of Korea Air Force Weather Group Research Program (2023UMM0343), and was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (RS-2023-00250021).