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AMOFSG/7-IP/10/ AMOFSG/7-IP/10
28/8/08
AERODROME METEOROLOGICAL OBSERVATION AND FORECAST STUDY GROUP (AMOFSG)
SEVENTH MEETING
Montréal, 9 to 12 September 2008
Agenda Item / 5: / Aerodrome observationsAgenda Item / 6: / Aerodrome forecasts
AUTOMATED THUNDERSTORM ALERT SYSTEM
(Presented by Sue O'Rourke and Bryan Boase)
SUMMARY
This paper provides an overview of the Automated Thunderstorm Alert Service (ATSAS) which was developed to support ground operations at major Australian Civil and Defence Airports.1. INTRODUCTION
1.1 Thunderstorms and the associated weather phenomena have a range of impacts on aviation operations from both safety and economic perspectives. The impacts include disruption to the management of air traffic both enroute and in the terminal area, and disruptions to airport ground operations.
1.2 One area of particular concern has been the impact of lightning on airport ground operations and the associated Occupational, Health and Safety issues. A number of airport ground staff in Australia have suffered from the impacts of lightning strikes in the terminal area and this has required the development of procedures to enhance safe operations. This includes the provision of alerts by the Australian Bureau of Meteorology when thunderstorms and associated lightning are likely in the vicinity of designated airports. Ground operations then cease for the duration of the alert. When this occurs, aircraft movements effectively cease as they cannot be unloaded, refuelled and nor can they leave their aircraft parking bay. The situation is further exacerbated when there are no vacant aircraft parking bays with air bridges available to enable the disembarking of arriving passengers. The tarmac area is restricted during thunderstorms and lightning events occurring in the vicinity of the airport. The flow-on of the disruption nationally, can have an impact that lasts for many hours.
1.3 In the past the thunderstorm alerts were prepared manually and their effectiveness was limited. They tended to be overly conservative and did not provide real-time information on the short-term improvements that can occur during periods of convective weather. It was recognised that there was a need for better real time information about thunderstorms and lightning, to enable better strategic and tactical planning of ground operations by the airlines without compromising safety requirements.
1.4 The World Meteorological Organization (WMO) Commission on Aeronautical Meteorology (CAeM) has organized an Expert Team on New Terminal Forecast (ET-NTF) which is tasked with developing a new terminal forecast for consideration by the next conjoint WMO CAeM session/ICAO MET Divisional Meeting to be held in the 2013/2014 timeframe with a view to world-wide adoption. The ET-NTF has identified that there is a lack of adequate information on thunderstorms, including quantitative details regarding lightning and hail size, from the beginning of descent through to landing. They have also identified the need for the information to be presented in a graphical format for which there is currently no formal international framework, although many countries have established systems similar to ATSAS.
1.5 In order to satisfy aviation industry and Australian Defence Force requirements the Automated Thunderstorm Alert Service (ATSAS) was developed to provide better real-time information on the presence of thunderstorms and associated lightning around identified airports. ATSAS is now being progressively introduced at airports around Australia. Systems that support ATSAS take radar and lightning data and automatically generate end-user graphical and text products that show the location and movement of thunderstorm cells and the presence of lightning within 30nm of the airport. The airlines and airport authorities have developed response procedures that enable them to better manage the disruption and minimise impacts.
2. The ATSAS System
2.1 ATSAS (Automated Thunderstorm Alert Service) is a totally automated system based on a number of software and instrumentation technologies (see Figure 1), including:
o Weather radar;
o Vaisala TSS928 thunderstorm sensor;
o TITAN (Thunderstorm Identification, Tracking, and Nowcasting) software; and
o AutoTIFS (Automated Thunderstorm Interactive Forecast System) software.
Figure 1. The ATSAS System
2.2 The radar performs a volumetric scan feeding the data to TITAN which interprets the data and identifies any thunderstorms via a number of classification techniques. The thunderstorm size, location, direction of movement and speed are calculated within TITAN. The lightning data from the TSS928 and the TITAN thunderstorm data are transmitted to AutoTIFS which integrates the data and generates the graphical and text ATSAS products.
3. Graphical ATSAS Products
3.1 The graphical ATSAS products include a thunderstorm location map (see Figure 2) and a meteogram (see Figure 3).
3.2 The thunderstorm location map (see Figure 2) shows:
o The location of any thunderstorms and their forecast movement over the next thirty minutes.
o The number of cloud-to-ground lightning flashes detected in the past 10 minutes in each range/azimuth sector; and
o The total number of cloud-to-cloud lightning flashes detected in the past 10 minutes.
3.3 The meteogram indicates when thunderstorms are expected to be within 5, 10 and 30nm of the Aerodrome Reference Point.
Figure 2. ATSAS Thunderstorm Location Map
Figure 3. ATSAS Meteogram
4. Feedback from the Aviation Industry
Feedback from the aviation industry has for this service has been very positive. They have taken and supportive and active role in the development, implementation and evaluation of the system to ensure that the product is fit for purpose.
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