Resumen
One possibility to reduce the climate impact of aviation is the avoidance of climate-sensitive regions, which is synonymous with climate-optimised flight planning. Those regions can be identified by algorithmic Climate Change Functions (aCCFs) for nitrogen oxides (NO??
x
), water vapour (H2
2
O) as well as contrail cirrus, which provide a measure of climate effects associated with corresponding emissions. In this study, we evaluate the effectiveness of reducing the aviation-induced climate impact via ozone (O3
3
) formation (resulting from NO??
x
emissions), when solely using O3
3
aCCFs for the aircraft trajectory optimisation strategy. The effectiveness of such a strategy and the associated potential mitigation of climate effects is explored by using the chemistry?climate model EMAC (ECHAM5/MESSy) with various submodels. A summer and winter day, characterised by a large spatial variability of the O3
3
aCCFs, are selected. A one-day air traffic simulation is performed in the European airspace on those selected days to obtain both cost-optimised and climate-optimised aircraft trajectories, which more specifically minimised a NO??
x
-induced climate effect of O3
3
(O3
3
aCCFs). The air traffic is laterally and vertically re-routed separately to enable an evaluation of the influences of the horizontal and vertical pattern of O3
3
aCCFs. The resulting aviation NO??
x
emissions are then released in an atmospheric chemistry?climate simulation to simulate the contribution of these NO??
x
emissions to atmospheric O3
3
and the resulting O3
3
change. Within this study, we use O3
3
-RF as a proxy for climate impact. The results confirm that the climate-optimised flights lead to lower O3
3
-RF compared to the cost-optimised flights, although the aCCFs cannot reproduce all aspects of the significant impact of the synoptic situation on the transport of emitted NO??
x
. Overall, the climate impact is higher for the selected summer day than for the selected winter day. Lateral re-routing shows a greater potential to reduce climate impact compared to vertical re-routing for the chosen flight altitude. We find that while applying the O3
3
aCCFs in trajectory optimisation can reduce the climate impact, there are certain discrepancies in the prediction of O3
3
impact from aviation NO??
x
emissions, as seen for the summer day. Although the O3
3
aCCFs concept is a rough simplification in estimating the climate impact of a local NO??
x
emission, it enables a reasonable first estimate. Further research is required to better describe the O3
3
aCCFs allowing an improved estimate in the Average Temperature Response (ATR) of O3
3
from aviation NO??
x
emissions. A general improvement in the scientific understanding of non-CO2
2
aviation effects could make climate-optimised flight planning practically feasible.