Aviation Meteorology

Turbulence (난류)

Atmospheric turbulence affecting cruising aircraft in the upper troposphere and lower stratosphere (UTLS) has eddy sizes far smaller than global Numerical Weather Prediction (NWP) grid spacing, yet remains predictable through diagnostics based on its generation mechanisms, since energy cascades down from larger scales. We have developed the Global Graphical Turbulence Guidance (G-GTG) and the Wind Shear Guidance Module (WSGM), which provide turbulence intensity as the energy dissipation rate to the 1/3 power (EDR), along with probabilistic forecasts derived from the agreement among individual diagnostics.

Mountain Wave Turbulence (MWT; 산악파 난류)
MWT is generated by instabilities induced by large-amplitude mountain waves or their breaking, promoted by strong cross-mountain inflow and rapid changes in wind speed and stability. It is an important source of UTLS turbulence in mountainous regions worldwide, including Korea, Greenland, the Rocky Mountains, Alaska, and Iceland.

Clear-Air Turbulence (CAT; 청천난류)
CAT occurs in cloud-free regions of the UTLS, posing a hazard to cruising aircraft due to its limited visual detectability, and is primarily associated with strong vertical wind shear near upper-level jet streams and deformative flows related to frontogenesis. Jet stream changes under a warming climate are reported to have increased CAT frequency and intensity.

Low-Level Turbulence (LLT; 저고도 난류)
LLT occurs near the surface within the atmospheric boundary layer (ABL) and is critical to low-level flight operations. Using high-frequency sonic anemometer observations at Boseong, South Korea, we found that LLT depends on both large-scale forcings and surface stratification within the ABL.

Wind Shear Monitoring
Wind shear threatens aircraft stability during approach and departure and compromises space launch operations. We developed a forecast model (WSGM) and an observation-based real-time detection system, both operational at the Naro Space Center of the Korea Aerospace Research Institute (KARI).

 

Icing (착빙)

In-flight icing occurs as an aircraft conflicting to supercooled liquid waters (SLW) in clouds. It causes unforeseen degradation of aircraft performance and even can lead the aircraft to crashing to the ground in severe cases.

With advances in computing resources, numerical models have been improved in spatiotemporal resolution, dynamical cores and parameterizations, enabling better cloud forecasts. Icing forecast systems based on NWP models also have been developed and improved as the advancements.

We developed the Korean Forecast Icing Potential (K-FIP) algorithm for operational use of Aviation Meteorological Office under the Korea Meteorological Administration (refer to Kim et al. 2024 for details). The algorithm forecasts icing potential over global airspaces using predicted temperature, relative humidity, vertical velocity and cloud water contents, which are indirect indicators of the existence of SLW.

Convection (대류)

Deep convection contributes to severe weather hazards such as turbulence, lightning, and downbursts, making forecasts of the spatiotemporal distribution of deep convective areas important for safe and efficient Air Traffic Management (ATM).

To provide forecast guidance for convection near the Korean Peninsula, we developed a Multi-Model and -Diagnostic Ensemble (MMDE)-based forecast system using the Global Data Assimilation and Prediction System based on the Unified Model and the Korean Integrated Model.

With 22 predictors related to the physical properties and dynamical sources of convection, the system provides probabilistic and deterministic forecasts of areas where the 15 dBZ echo top height exceeds Flight Level (FL) 250 and FL350, respectively. Evaluation results suggest high potential for supporting the strategic planning of ATM.

Modeling of safe and efficient flight-route trajectories

Flight routes are routinely optimized using weather forecasts to support safe and efficient travel. Our research uses aircraft routing algorithms to translate atmospheric conditions into flight paths and quantify their effects on travel time and weather-related risks, with simulated routes evaluated against observed trajectories.

Jet streams shape flight routes and times, while nearby turbulence poses challenges to safety. By comparing routes that prioritize favorable winds with those that also avoid turbulence, we assess this trade-off, and our recent North Atlantic study showed that the growing time cost of avoiding turbulence can offset flight-time savings from changing winds.

We are now extending this perspective to the Pacific, focusing on how low-frequency climate variability shifts the jet stream and, with it, the preferred routes and travel times. Understanding these relationships may help anticipate changes in flight efficiency beyond daily weather forecasts, with implications for fuel use and emissions.