Search

ABSTRACT Turbulence is a major source of weather-related aviation incidents. There are many different indicators used to try and predict where turbulence is likely to occur. The indicators are derived from deterministic models although they are often quoted as probabilities. This paper proposes the use of ensemble forecasts from the Met Office Global and Regional Ensemble Prediction System ( MOGREPS) to produce a probabilistic indicator of wind shear and convectively induced moderate or greater turbulence. An objective verification scheme using high-resolution automated aircraft observations from the Global Aircraft Data Set is used to compare the skill with the routinely available World Area Forecast Centre gridded turbulence forecasts. The forecasts are assessed globally over a 12 month period from November 2010 to October 2011 looking at the skill, reliability and economic value of the forecasts. [ABSTRACT FROM AUTHOR]

In the morning of 5 March 2010, an aircraft experienced tail strike when it departed from the south runway of the Hong Kong International Airport to the west. This paper documents the meteorological conditions in the tail strike event, and discusses the alerting and the forecasting aspects of the event. Based on the analysis of the aircraft manufacturer, the tail strike is believed to arise from significant wind shear (headwind loss) experienced by the aircraft. By analysing the surface and the LIDAR observations, it appears that the significant wind shear is related to disruption of the background southwesterly flow by the complex terrain near the airport. From the surface observations, there is a microscale cyclone at the western part of the south runway. The radial velocity image of the LIDAR also depicts an area of reverse flow in that region against the background southerly flow. The alerting of the wind shear based on the two wind shear alerting algorithms developed by the Hong Kong Observatory is discussed, and it turns out that the anemometer-based wind shear algorithm could successfully capture this wind shear occurring close to the ground. On the other hand, due to geometrical constraint, the LIDAR does not pick up the headwind loss experienced by the aircraft. The forecasting of this wind shear event is considered by performing high resolution (down to a horizontal resolution of 50 m) using a mesoscale numerical weather prediction model. The simulated headwind profile at the event time is generally consistent with the aircraft data, though the headwind loss in the simulation is smaller than the reality. Together with the forecast wind gusts, it may be possible to alert the aviation weather forecaster at an earlier time about the occurrence of terrain-induced wind shear over the south runway in this particular event. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]