Mesoscale Severe Weather
1
Development of hazardous weather prediction system in aviation
Convective hazards
Atmospheric turbulence in the upper troposphere and lower stratosphere (UTLS) directly affecting cruising aircraft has horizontal eddy sizes of a few meters to a few kilometers. This is much smaller than the grid spacing of the current (and near future version of) global Numerical Weather Prediction (NWP) models.
However, because the energy of the large-scale disturbances cascades down to smaller scales, aircraft-scale turbulence can be logically predicted using the NWP model-based turbulence diagnostics formulated based on the turbulence generation mechanisms.
Global Graphical Turbulence Guidance (G-GTG) and Wind Shear Guidance Module (WSGM) have been developed for providing a metric of atmospheric turbulence intensity metric of energy dissipation rate to the 1/3 power (EDR). A probabilistic EDR forecast is also produced by relative percentage agreement of individual Clear Air Turbulence (CAT) and Mountain Wave Turbulence (MWT) diagnostics, which improves the current global forecast skill.
Heavy Snowfall
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.
2
Understanding generation mechanisms of weather hazards through high-resolution modeling
Downslope Windstorm
Mountain wave turbulence (MWT) is one of the important sources of atmospheric turbulence in the upper troposphere and lower stratosphere (UTLS), which is generated by static or shear instability induced by large-amplitude mountain waves or their breaking.
MWT occurs in the mountainous regions all around the world, such as Korea (Kim and Chun 2010), Greenland, Rocky Mountains, and Iceland.
Mechanisms of MWT need to be investigated more in detail in the various background flows and regions.
We are studying the generation and evolution mechanisms of MWT in the southern mountainous region of Alaska using high-resolution numerical simulations (dx = 200 m). Although many commercial aircraft pass through this region, there is no previous study on mechanisms of MWT in the UTLS in this region.
Using the simulation results, we can investigate the detailed structures of mountain waves and turbulence, which cannot be analyzed in the reanalysis and observation data available now. Also, we can examine sensitivity on the turbulence to the physical parameterization scheme and compare simulation results with aircraft observation data.
Fog
TBA