Climate cost functions
Climate cost functions indicate for an emission what is related
climate impact if emission is released at that location and that
specific time. Hence, such 4-dimensional climate cost functions
allow to quantify related climate impact for any given location
and time of emission.
How to calculate climate cost functions
Within REACT4C a simulation tool will be prepared in order to
calculate the time evolution of the perturbations of the atmospheric
composition and cloudiness arising from unit emissions released from
aviation (e.g. NOx, H2O) at a high number of latitude-longitude-altitude
model grid cells. This analysis will be performed for the archetypical
weather situations selected earlier (WP1). Due to a Lagrangian
advection scheme ATTILA a very high number of such perturbations
can be included within one single model simulation, excluding
interaction of the individual perturbations.
Radiative forcing as input to climate cost functions
The radiative forcings (RFs) arising from the unit perturbations will be
calculated for each of the perturbations as functions of time.
The result will be individual 5-dimensional functions of global (marginal)
radiative forcings as functions of time t (after emission),
location (longitude, latitude), pressure altitude p and time
of emission te, separately for the different types of emissions
(NOx, H2O, contrails). Due to the long lifetime and the small
perturbation of the background concentrations the RFs from CO2
and CH4 can be derived via box models.
The time dependent RFs will form the input for calculating the 4D (specific)
climate cost func-tions. We will concentrate on the incremental integrated RF
(if a GWP based emission metric is used) and on the incremental temperature
change (if a GTP based emission metric is used). The output will serve as
climate/environmental cost functions quantifying impact of CO2, NOx, and
H2O emissions, and of contrails (plus potentially contrail-cirrus) for a
set of typical weather situations. For illustrative purposes we shall also
consider the marginal radiative forcing as cost function.