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 observations
Agenda 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.
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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.
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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
o
o
o
The thunderstorm location map (see Figure 2) shows:
The location of any thunderstorms and their forecast movement over the next thirty minutes.
The number of cloud-to-ground lightning flashes detected in the past 10 minutes in each
range/azimuth sector; and
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.
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Validity times of radar &
lightning data. Radar is
usually updated every 10
minutes & lightning every
minute
Software
version
number
Total number of
cloud-to-ground
strikes in the
last 10 minutes
in this sector
Thunderstorm
cell and track
Legend
Figure 2. ATSAS Thunderstorm Location Map
Figure 3. ATSAS Meteogram
Total number of cloud-tocloud lightning strikes
detected in the last 10
minutes
Range rings:
- 5nm
- 10nm
- 30nm
Scale in nautical miles (nm)
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4.
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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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