Observatory's new initiatives help reduce impact of aviation on the climate
Since the Airport Authority Hong Kong (AAHK) launched the Hong Kong International Airport (HKIA) Master Plan 2030 for public consultation in early June, there has been much debate locally about the potential impact of the increase in air traffic on the environment. In the international arena, there is also increasing awareness about the impact of climate change on the future of the aviation industry. The impact can be broadly divided into three aspects :
1) Climate change may lead to increased frequency and severity of hazardous weather, thus impacting aviation operation. For example, in Hong Kong, the average number of heavy rain days (days with hourly rainfall greater than 30 mm) per year increased by about 0.41 day per decade from 1947 to 2010 (Figure 1).
2) On the longer term, climate change may affect aviation infrastructures and route planning. For example, the rise in sea level may increase the risk of coastal airports being affected by storm surges.
3) Climate change may also impact the viability of popular holiday destinations. For example, the rise in sea level may affect popular tourist destinations such as Maldives while the lack of snow may affect skiing spots in the alpine countries.
The International Civil Aviation Organization (ICAO) adopted in last year a resolution to a globally harmonized agreement for addressing the carbon dioxide emissions. While the main contribution to reduction in carbon dioxide and aerosol emission from air traffic will likely come from improved fuel efficiency and the use of alternative fuel, the World Meteorological Organization (WMO) and the meteorological services have started to work hand-in-hand with the aviation community on emission reduction through improvement in aviation operation efficiency.
While travelling, many of you might have experienced planes circling at holding area due to weather or busy air traffic at the airport. Indeed, bad weather, such as tropical cyclones or thunderstorms, could cause significant impact to air traffic management operations and reduction in airport capacity. If accurate forecast of the timing and severity of the weather could be provided to air traffic control (ATC), prior arrangements could be made in the planning of air traffic flow to optimize flight operations, thus reducing the unnecessary fuel burnt due to holding. To achieve this, a new initiative is being undertaken by WMO in close collaboration with ICAO to develop the new Meteorological Services in the Terminal Area (MSTA) to better support air traffic management in the wider terminal areas.
Locally, to demonstrate the benefit of this new initiative, a new product, known as the Significant Convection Monitoring and Forecast, has been made available for trial use by Hong Kong ATC since June 2010 (Figure 2). The product provides forecasts of the chance of significant convection in the arrival and departure corridors and in the major holding areas, for the coming 1 hour and up to 12 hours ahead respectively. The impact to ATC is represented in three levels, viz. low, medium, high, which are indicated in green, yellow and red colors respectively. The product is very much welcomed by the controllers as it gives them information on the possible location of inclement weather elements and helps anticipate their impact on the air traffic flow. The product is showcased in the latest edition of the ICAO Journal and has recently been enhanced in response to user feedback.
In addition, the Observatory has also developed the Aviation Thunderstorm Nowcasting System (ATNS) to provide short-term thunderstorm forecast for the next hour (Figure 3). ATNS is developed from the Observatory's nowcasting system which was showcased in major international events including the Beijing Olympics in 2008, the Shanghai World Expo in 2010, and recently the Shenzhen Universiade. It automatically determines the movement of thunderstorms from the radar image sequence every 6 minutes and forecasts the location of thunderstorms in the next 60 minutes by extrapolation based on artificial intelligence technique.
While meteorologists are helping the aviation community to limit or reduce carbon dioxide emissions from international aviation, thus contributing to the global efforts to address climate change, in return the aviation community contributes towards a better understanding of the atmosphere by providing invaluable weather data made by commercial aircraft through real-time transmission of weather observations measured on-board the aircraft to ground. In this regard, local airlines contribute typically over 1,000 observations per day to the Observatory and other WMO members.
As the saying goes, "Challenges open up opportunities". This is a good example of how the Observatory and the aviation industry face the challenges through innovative thinking and collaboration. Sincerely hope that all communities could join force and work hand-in-hand to combat climate change!
Sharon Lau and C M Shun
Figure 1 Number of heavy rain days (days with hourly rainfall > 30mm) recorded at the Hong Kong
Observatory Headquarters (1947-2010) increased at a rate of about 0.41 day per decade.
Figure 2 Significant Convection Monitoring and Forecast supporting air traffic management in the wider
terminal area of the Hong Kong International Airport (HKIA).
Figure 3 Aviation Thunderstorm Nowcasting System (ATNS) providing short term thunderstorm forecast for
HKIA and its approach and departure corridors.
 Herbert Puempel (2011) : "In-situ Aircraft and Atmospheric Science: A Unique Collaboration", ICAO Journal, Vol. 66, No. 3, 32-36.