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Meteorological weather situations
Within REACT4C a set of representative meteorological situations
will be derived which will be used in subsequent work packages (WPs)
as input for flight planning and assessment of the climate impact of different choices of flight routes.
The underlying concept will be to identify a number of distinct weather
situations for which standard flight planning tools (which generally aim
to minimise fuel use) generate distinct choices of routes. For these distinct
weather situations, climate cost functions (WP2) are diagnosed and
flight routings will be identified, that minimize fuel consumption,
emissions and environmental impact, respectively (environmental flight
planning, WP3).
Characterization of distinct weather situations
Operationally-derived optimal flight routes, provided to
national air traffic services, will be used in conjunction
with meteorological analyses from weather forecast centres,
to identify distinct meteorological situations which lead to
different recommended routes - these will include cases for
which the recommended routes are close to great circle routes,
and those that deviate most markedly from great circle routes,
either to the north or south. For example, within the North Atlantic,
routing will depend on the presence of cyclonic and anticyclonic
conditions and the position and strength of the jet stream, and
the routing will be different for eastbound and westbound flights.
It is important that the idenfified weather situations are not
extreme, but rather cases that occur with sufficient frequency
to make an analysis of different routing options (accounting
for more than just fuel use) worthwhile.
Use of GCM for calculation of cost functions
The data for cost function calculations will be generated by a
General Circulation Model (GCM), instead of from meteorological
analyses or re-analyses in order to be able to easily repeat
identical CCM simulations including contrails (potentially
plus contrail cirrus), aerosol effects and modifications of
chemical composition. Another reason for using CCM data is that
radiative forcing (RF) calculations are possible online. Hence,
an important task will be to identify weather situations within
the GCM that correspond closely to the distinct weather situations
derived from the reanalysis data.
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