Numerical Simulation of Turbulence near the Surface When an Accident Occurred at Narita Airport

A serious accident occurred when an airplane landed at Narita Airport at 1323 JST on 20 June 2012. The weather was fine, but strong south-westerly winds were presented. In such a case, turbulence organized as roll-shaped convection can occur in the atmospheric boundary layer. The rolls align parallel to the south-westerly, and the wind may significantly vary between updraft and downdraft regions. The airplane was indeed encounter highly fluctuated winds during the landing. A Doppler-Lidar placed at the airport observed patterns that seem to be associated with the roll-shaped convection.

We conducted a numerical simulation of this case to reproduce the turbulence. A reginal weather prediction model, Japan Meteorological Agency’s Non-hydrostatic Model (Saito et al., 2006), was used. Numerical domains were centered at Narita Airport. Outer-run was performed with horizontal resolution of 1 km. Its initial and boundary conditions were given by the Meso-Scale analysis provided by Japan Meteorological Agency. Inner-run was nested in the outer-run, and its horizontal resolution was 100 m.

Results of the outer-run shows that strong south-westerly prevails due to a synoptic low in the north-east. The result of the outer-run reveals that the south-westerly is locally enhanced on the Tokyo Bay. The Narita Airport is located only several ten kilometers away from the Tokyo Bay in the south-west and is exposed to the enhanced winds.

In the inner-run which has resolution fine enough to be a large eddy simulation, the roll-shaped convection is simulated around the airport. Resolved structures of the convection are similar to the one observed by the Doppler-Lidar operated at the airport. Gusty winds accompanied by the convection are indeed reproduced. Latest fine resolution simulation is shown to be useful for accessing and predicting turbulence near the surface.