TNAG-1174-FCO40-1476-Proposed-replacement-airport-for-Hong-Kong-at-Deep-Bay-or-Ch-1982 — Page 110

CONFIDENTIAL

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4.

TURBULENCE AND WIND SHEAR

(a)

Effects of nearby terrain

Since hills in China are not high (500 m) and most are more than a

few kilometres away from the proposed airport site, the chance of severe turbu-

lence in northerly winds is rather small.

The tentative flight path between Lau Fau Shan and Mai Po is downstream

of Kai Kung Leng (572m; 1876 ft) and Tai To Yan (565 m; 1854 ft) in an easterly

airstream. A water tank experiment using a Hong Kong territory model has shown

that the northeast-southwest oriented range associated with Tai To Yan is an

effective block to easterly surface flow in conditions simulating winter monsoon

conditions. During surges of the winter monsoon, inversions are typically found

in the layer between 500 m and 1500 m. It appears that waves could be generated

at about the height of the peak during an easterly surge, especially when the

inversion is at an altitude of about 500 m. Experience with the water tank

suggests that the waves will have wavelengths in the range of 2-8 kilometres,

depending on the wind speed. As Kai Kung Leng is situated about 4 kilometres

downstream of. Tai To Yan, during an easterly surge, standing waves

complex flow patterns may arise and could cause hazards to low flying aircraft

in the Tsim Bei Tsui Mai Po area.

or other

The range of hills extending from Castle Peak north-northeastward

towards Lau Fau Shan is quite close to the proposed airport site. However, the

hills are not high and the height of the ridge line is generally between 200 m

and 300 m.

Since this is much lower than the typical inversion height, significant

mountain waves are unlikely to be generated. However, the possible occurrence

CONFIDENTIAL