Inventory of aircraft emissions over the Taiwan area

The inventory of aircraft emissions over the Taipei Flight Information Region (FIR) has been developed with 1997 as the baseline year. We first analyze the spatial and temporal distribution of flight frequency based on the official civil aviation monthly reports, airline flight schedules and pilots) on-air reports. Fuel consumption and trace-gas emissions are then calculated by using the engine performance database of the International Civil Aviation Organization (ICAO) and a few other data sources. The emission inventory is further classified according to the flight types (domestic or international), aircraft types (passenger jets, cargo jets or propeller aircraft), as well as the state of aircraft operation (idle, takeoff, climb-out, cruise and approach/landing). Engine types, number of engines per aircraft, as well as engine performance at different operation states are all considered in estimating the emission rates. The emission rates of six trace chemicals (NOx, CO, CO2, S, HC and H2O) are estimated for all flight routes and airports, and at different cruise altitudes. To get a sense of their relative importance, we compared the total emissions from aircraft over the Taipei FIR with those from the ground transport in Taiwan. The ratios we obtained are 14.5% for NOx, 9.5% for S, CO2 and H2O, 0.86% for CO, and 0.42 % for HC. About 85 % of the NOx and 80% of the S, CO2 and H2O were emitted into the upper troposphere, whereas most of the CO (74%) and HC (60%) were produced on the surface. A further comparison shows that the amount of aircraft-produced NOx over the Taiwan area is about 69% of those produced over Mainland China, and aircraft-produced sulfur is about 1.1% of those produced globally.