Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
This section describes the scenarios for supersonic aircraft in 2015 and 2050 that were evaluated for this assessment. The premise for the future supersonic (proposed
hypothetical HSCT) aircraft fleet is given in Chapter 9, along with descriptions of actual emissions databases. A subsonic fleet is included in all scenarios but is
modified when an HSCT fleet is also present. The background atmosphere for the model scenarios was appropriate to either 2015 or 2050, though parametric studies
of reactive chlorine (Cl y ) concentration and background SAD were also performed.
4.3.2.1. Background Atmospheres
Boundary conditions for the background atmosphere for long-lived gases for 1992, 2015, and 2050 (Table 4-8) are based on the IPCC IS92a scenario (IPCC, 1992,
1995). The boundary conditions used for halocarbons correspond to (a) 3.7, 3.0, and 2.0 ppbv of Cl y in the upper stratosphere at 50 km at the Equator for 1992, 2015,
and 2050, respectively; and (b) 15, 12.5, and 11.1 pptv of reactive bromine (Br y ) in the upper stratosphere at 50 km at the Equator for 1992, 2015, and 2050,
respectively.
Background sulfate SAD was supplied for the unperturbed stratospheric aerosol case as described in Table 8-8 in WMO (1992). This case is designated SA0 aerosols.
To approximate the effects of an active period of volcanic eruptions (e.g., the past 2 decades), some scenarios also evaluate the effects of 4xSA0. Treatments of PSCs
and associated chemical and dynamical processes differ among models.
4.3.2.2. Aircraft Emission Scenarios
Table 4-11: Percentage changes in total column ozone for each assessment model. The top value is for the Northern Hemisphere average; the bottom value is for the
Southern Hemisphere average. The cruise altitude for most HSCT scenarios is at a standard (Std) height. Source gas boundary conditions are for the year 2015.
Model results have been rounded off to one significant figure for clarity.
IPCC
Scenario
S1a
No H 2 O
S1b
H 2 O only
S1c
S1d
S1e
Cly (ppbv)
3.0
3.0
3.0
3.0
3.0
Fleet
Size
500
500
500
500
500
EI(NO x ) Altitude
(km)
5
0
5
10
15
Std
Std
Std
Std
Std
http://www.ipcc.ch/ipccreports/sres/aviation/049.htm (6 von 13)08.05.2008 02:42:26
SAD Desc. Ref.
Atm.
SA0
SA0
SA0
SA0
SA0
D
D
D
D
D
AER -2D GSFC-2D UNIVAQ-2D LLNL-2D CSIRO-2D THINAIR-2D SLIMCAT-3D SCTM1-3D LARC-3D
-0.07
-0.03
-0.6
-0.3
-0.3
-0.1
-0.3
-0.1
-0.3
-0.05
-0.1
+0.03
-0.4
-0.8
-0.4
-0.8
-0.6
-0.7
-0.8
-0.7
+0.2
+0.1
-0.4
-0.2
-0.002
+0.02
+0.2
+0.1
+0.4
+0.2
-0.01
+0.1
-0.3
-0.3
-0.2
-0.2
-0.3
-0.1
-0.4
-0.01
-0.09
-0.07
-0.3
-0.07
-0.2
-0.1
-0.3
-0.2
-0.5
-0.3
-
-
-
-
-0.2
-0.2
-0.5
-0.3
-0.9
-0.5
-0.2
-0.09
-0.6
-0.7
-0.4
-0.6
-0.5
-0.7
-
-
-0.2
-0.007
-
-
-0.3
-0.1
-
-
-
-
-
-
-
-
-0.05
-0.1
+0.07
-0.03
-
-