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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
