WMO Symposium Toulouse 2005 Wind Forecasting at Hong Kong International Airport S.Y. Lau Hong Kong...

WMO SymposiumToulouse 2005

Wind Forecasting at Hong Kong International

Airport

S.Y. LauHong Kong Observatory

WMO SymposiumToulouse 2005

2 types of user requirements

• Air traffic controllers – Runway change – headwind/tailwind

• Dry – 10 kt, Wet – 5 kt• Nowcasting – extension of monitoring network

through the installation of weather buoys and LIDAR

• Airlines/pilots– Crosswind limit

• Wide body plane - 20 kt• Usually of the order of 18 to 24 hours – statistical and

probabilistic forecast

WMO SymposiumToulouse 2005

Strong crosswind due to Kompasu

WMO SymposiumToulouse 2005

Probability of 20 kt crosswind if the forecast track is perfect

Probability isopleths

4

17

WMO SymposiumToulouse 2005

Track perturbation

• Statistical– Based on past (1999-2002) forecast

position errors

• Dynamical– Based on NWP model spread from model

ensemble– ECMWF, JMA, NCEP, UKMO, JMA Typhoon

model, HKO ORSM

WMO SymposiumToulouse 2005

25 perturbed tracks within 85% the bivariate Gaussian

distribution for position uncertainties

11

22

33

44

5 5

66

77

88

9910

10

11 11

1212

1313

14

14

15

15

1616

1717

18

18

19

1920

20

2121

2222

23 23

2424

25

25

25

1)(|

k kkI trPrWPtP

WMO SymposiumToulouse 2005

Track of Kompasu

July 2004

WMO SymposiumToulouse 2005

statistical

dynamical

WMO SymposiumToulouse 2005

WMO SymposiumToulouse 2005

User Interface

WMO SymposiumToulouse 2005

WMO SymposiumToulouse 2005

Limitations

• Probability isopleths not separated according to TC intensity

• Size of TC not taken into account• Asymmetric structure of TC not taken

into account• Arrival/presence of northeast

monsoon could result in earlier onset of high crosswind

WMO SymposiumToulouse 2005

Thank you

WMO SymposiumToulouse 2005

Tornado on 6 Sep 2004

WMO SymposiumToulouse 2005

extension of monitoring networkextension of monitoring network Nowcasting

WMO SymposiumToulouse 2005

AWAREAWARE

• AWARE (Anemometer-based Windshear Alerting Rules – Enhanced) launched in mid-2004

• Based on wind readings at 6 runway anemometers & TMT & 5 weather buoys

• Alerts out of ground truths

TMT

Weatherbuoys

Runway anemometers

Weatherbuoy

WMO SymposiumToulouse 2005

AWARE alert

WMO SymposiumToulouse 2005

Merits of AWARE…Merits of AWARE…

• Enhanced detection of WS associated Enhanced detection of WS associated with:with:– Sea breezeSea breeze– Gust frontGust front– Shear lineShear line

WMO SymposiumToulouse 2005

Nowcastingextension of monitoring networkextension of monitoring network

WMO SymposiumToulouse 2005

Kompasu

Hong Kong