Atmospheric turbulence is a primary meteorological hazard to en-route air traffic. The role of Clear Air Turbulence (CAT) for various processes in the atmosphere is still ambiguous. An Air India flight AI462 encountered severe CAT on 19 April 2018. The present study simulates the CAT event and is focused on understanding and investigating favourable conditions for the occurrence of CAT. Weather Research and Forecasting (WRF) Model V4.0.3 has been used to simulate the turbulence. The 6-hourly NCEP FNL Operational Global Analysis data at 0.25° X 0.25° resolution is taken as input to provide the model's initial and lateral boundary conditions. For simulating the atmospheric environments at the time of the event, Yonsei University Scheme, WSM 3-Class Simple Ice Scheme, Kain-Fritsch (New-Eta) Scheme, Rapid Radiative Transfer Model (RRTM) Scheme, and Revised MM5 Monin-Obukhov Scheme are used. This study shows that Vertical Velocity, Geopotential Thickness, Wind Shear and Bulk Richardson Number Shear are correlated with CAT as the model predicted both upward and downward velocity very close to each other between 400 hPa and 550 hPa levels along with strong geopotential thickness gradient and strong wind shear gradient near the accident location. This could lead to CAT. Model simulated variations in CAT Index with change in time and pressure levels. CAT dissipates as we go higher in the atmosphere above 550 hPa.
Research Article
Numerical Simulation of a Clear Air Turbulence (CAT) Event Over Northern India Using WRF Modelling System
https://doi.org/10.21203/rs.3.rs-1231233/v1
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Clear Air Turbulence
vertical wind shear
CAT Index
Ellrod’s Index
aviation meteorology
aircraft hazards.
