Sensitivity of direct effect to
aerosol treatment
(first results)
Peter Hess
Current Aerosol Types
-Dust: 4 size bins
-Seasalt: 4 size bins
-OC1, OC2: OC1->OC2 (1.2 days)
-BC1, BC2: BC1->BC2 (1.2 days)
-Sulfate (Several different Treatments)
-Ammonium nitrate (Only when running w/ chemistry)
-SOA (Only when running w/ chemistry)
Æ All are considered externally mixed.
Aerosol Parameterizations
(Simple -> Complex)
• Prescribed (4th Assessment Report)
• No Chemistry Option
C
– Prognostic OC, BC, Dust, SeaSalt
– Sulfate with input oxidants (NO3, O3, HO2) SO
– No NH4NO3 NH4NO3
• Chemistry Option
–
–
–
–
C
Prognostic OC, BC, Dust, SeaSalt
Sulfate
S
NH4NO3, simple partitioning with SO4. NH4NO3
SOA
Recommendation for 5th Assessment
• Accuracy of Input Oxidant Approach ?
• Importance of Ammonium Nitrate ?
– Do we need to include in some form?
Simulations (Complex to Simple)
1) Aerosols: All
S
C NH4NO3
Chemistry: Yes
2) Aerosols: No ammonium nitrate, SOA
C NH4NO3 S
Chemistry: Yes
3) Aerosols: All, but SO2 emissions at 50%
NH4NO3 S
Chemistry: Yes C
4) Aerosols: All, but sulfate diagnosed using Rasch
code (designed for prescribed oxidants)
Chemistry: Yes C NH4NO3 SO
5) Aerosols: Sulfate from Rasch code.
Chemistry: Input oxidants C NH4NO3 SO
MISER
0.6
CAM
C
0.3
NH4NO3
S
0.0
Pfister et al, 2007
Bratts_Lake ( 50N,
Bratts_Lake ( 50N,
255E, 586m)
1.5
AOT_500
AOT_500
1.5
1.0
0.5
0.0
Jan
Apr
0.4
0.3
0.3
0.2
0.1
0.0
Jan
Apr
Stennis ( 30N,
Oct
Jul
Stennis ( 30N,
AOT_500
AOT_500
Apr
270E, 20m)
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Jan
Apr
0.4
0.3
0.2
0.1
0.0
Jan
Oct
Jul
BONDVILLE ( 40N,
0.8
0.6
0.6
0.4
0.2
0.0
Jan
Apr
Jul
Walker_Branch ( 35N,
0.6
AOT_500
0.6
Apr
Jul
Oct
Apr
Jul
Walker_Branch ( 35N,
275E, 365m)
0.8
0.0
Jan
271E, 212m)
0.2
0.8
0.2
Oct
Jul
0.4
0.0
Jan
Oct
0.4
Apr
BONDVILLE ( 40N,
271E, 212m)
0.8
AOT_500
AOT_500
262E, 318m)
0.1
270E, 20m)
0.6
0.5
AOT_500
Oct
Jul
0.2
0.0
Jan
Oct
Jul
Apr
Cart_Site ( 36N,
262E, 318m)
0.4
AOT_500
AOT_500
Cart_Site ( 36N,
255E, 586m)
AERONET (92-05)
MODIS (2001/05)
MISR (2001/05)
0.5
0.0
Jan
Oct
Jul
1.0
DUST
SALT
SO4
CARB
Oct
275E, 365m)
0.4
0.2
0.0
Jan
Apr
Jul
Oct
(courtesy Colette Heald)
Full Chemistry vs Prescribed Oxidants
Difference Fields:
C NH4NO3 S
minus
C NH4NO3
0.2
∆
AOD
0.0
-0.2
SO
IMPACT of AMMONIUM NITRATE
Difference Fields:
C NH4NO3 S
minus C
NH4NO3
0.2
∆
AOD
0.0
-0.2
6.
3.
∆
FSNTOAC
(w/m2)
0.
-3.
-6.
S
IMPACT of AMMONIUM NITRATE
Difference Fields:
C NH4NO3 S
∆
minus C
NH4NO3
0.25
0.2
AOD
NH4NO3
0.1
0.0
-0.25
-0.2
∆
AOD
SO4
-0.1
0.0
S
IMPACT of AMMONIUM NITRATE w/ 50% SO2 Emissions
C
NH4NO3
S
minus C
NH4NO3
S
0.
∆
AOD
-.3
-.6
-.01
∆
-.12
FSNTOAC
(w/m2)
-1.
-3.5
50%
IMPACT of AMMONIUM NITRATE w/ 50% SO2 Emissions
Difference Fields:
C NH4NO3 S
minus C
NH4NO3
0.25
∆
AOD
0.0
-0.25
6.
3.
∆ FSNTOAC
(w/m2)
0.
-3.
-6.
S
Full Chemistry vs Prescribed Oxidants
Difference Fields:
C NH4NO3 S
Maximum
∆
minus C
AOD is 0.1
NH4NO3
SO
Prescribed vs Active Chemistry
Difference Fields:
C NH4NO3 S0
∆
minus
C
NH4NO3
SO
0.12
AOD
0.0
Conclusions
• Sulfate with input oxidants – works well!
• Large regional differences with NH4NO3
• Next Steps?