[A-CG31] Aircraft and UAV Observations for Earth-planetary sciences

[ACG31-02] Large Eddy Simulation on Horizontal Rolls in Atmospheric Boundary Layer at Narita Airport and its Evaluation

*Junshi Ito¹, Hiroshi Niino², Katsumi Yoshino (1.Tohoku University, 2.Atmosphere and Ocean Research Institute, The University of Tokyo)

Fronts and downbursts are known to be severe threats to airplanes during takeoff and landing. However, it is less known that there is another type of danger under fair weather conditions. An aircraft landing at Narita International Airport, Japan, encountered rapid changes of wind and turbulence in the afternoon of 20 June 2012 when south-westery winds prevailed. It causes a hard-landing, resulting in several injuries and damage to the fuselage. A Doppler lidar for monitoring low-level winds at the airport observed alternating regions of strong and weak winds aligned southwest--northeast, perpendicular to the runway.

In order to clarify the detailed structure and mechanism of these disturbances, numerical simulations using a fine-resolution (horizontal resolution: 100 m) nested in a coarse-resolution (horizontal resolution: 1 km) are made. The simulations show that horizontal convective rolls, which occur in convective boundary layers with strong vertical shear, were prevailing. These rolls are associated with the rapid changes in wind speed and turbulence similar to those observed by the Doppler lidar and flight recorder.

The present study demonstrates that the large eddy simulation is useful for clarifying the structure and mechanisms of horizontal convective rolls and forecasting them. We will also show on-going research in a case with northwesterly winds.