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Recent activities on aerosols in TM5
Achim StrunkTwan van Noije, Michiel van Weele
• AeroCom-2 contribution by KNMI
• Preliminary source sink analysis
• Online dust module
• EC-Earth/TM5 decadal runs
TM-Meeting Wageningen 2011-11-29
AeroCom-2: Overview
• Aerosol Comparisons between Observations and Models• “The AEROCOM-project is an open international initiative of
scientists interested in the advancement of the understanding of the global aerosol and its impact on climate.”
• AeroCom-1: accomplished before IPCC-AR4• AeroCom-2: Ongoing, next stimulus is IPCC-AR5; contribution by
many groups/models (CAM*, ECHAM*, FMI-SALSA, GeosChem, GISS*,
GLOMAP, GMI, GOCART, HadGEM, LSCE, OsloCTM, SPRINTARS, TM5, …) to various experiments (hindcast, direct/indirect forcing, …)
• TM5 contribution to AeroCom-1 by Maarten & Frank• TM5 contribution to AeroCom-2 by Twan & Achim
– HCA-IPCC (years 2000-2009), including target year 2006
– pre-industrial simulation (1850)
– TM5 chem V3 with a few new features
– AR5 (RCP4.5) emissions with natural/biogenic/soil/oceanic from MACCity
TM-Meeting Wageningen 2011-11-29
AeroCom-2: Diagnostics
• 0d (@ stations): – hourly means of full aerosol tracer information (2006)– daily means of full aerosol tracer information (1850, HCA)
• 1d (@ stations), vertical profiles: – daily means of of full aerosol tracer information, dry aerosol extinction &
absorption PM10 (2006)
• 2d:– daily means of optical properties (1850, HCA):
• AOD @ {550,440,870}nm, fractions for {SO4,NO3,BC,OA,Dust,SS,H2O}• fine-mode AOD, absorption AOD, asymmetry parameter, dry aerosol
extinction / absorption PM10, ambient aerosol extinction
– daily means of {emissions, surface concentrations, wet/dry deposition, load, nitrogen budget} (1850, HCA)
– daily means of nitrogen budget (1850, 2006)– daily means of SW & VIS radiation fields (1850, 2006) Twan
• 3d: – monthly means of extinction, absorption, asymmetry param., etc. – monthly means of full aerosol tracer information, etc. (1850, 2006)
TM-Meeting Wageningen 2011-11-29
AeroCom-2
Participating in the following studies:• radiative forcing (Gunnar Myhre)• all-aerosol-tracer (Graham Mann)• organic aerosols (Kostas Tsigaridis)• snow & ice radiative forcing (Mark Flanner)• hindcast evaluation (Michael Schultz)• … • no active participation from KNMI foreseen
Most striking result by TM5:
Very low global mean AODs!
TM-Meeting Wageningen 2011-11-29
AOD
TM-Meeting Wageningen 2011-11-29
Revision 2
• Bugs discovered: – SO2 emissions high by a factor of 2 (SO4 correct)
– SeaSalt emissions low by a factor of 2 (mass)
– NH3 emissions 20% low
re-run, re-submit to AeroCom database
before after
TM-Meeting Wageningen 2011-11-29
AOD against observations
bias: -0.111
TM-Meeting Wageningen 2011-11-29
AOD fine mode against observations
bias: -0.093
TM-Meeting Wageningen 2011-11-29
Absorption AOD against observations
TM-Meeting Wageningen 2011-11-29
Possible reasons
1. Sources for aerosols too low (emissions)
2. Sinks for aerosols too high (deposition, sedimentation) lifetime!
3. Ageing and coagulation too fast in M7 (too few coarse particles)
4. Hygroscopic growth underestimated
5. Optics wrong
6. Combinations of 1. - 5.
7. …?
TM-Meeting Wageningen 2011-11-29
Possible reasons
1. Sources for aerosols too low (emissions)
2. Sinks for aerosols too high (deposition, sedimentation) lifetime!
3. Ageing and coagulation too fast in M7 (too few coarse particles)
4. Hygroscopic growth underestimated
5. Optics wrong
6. Combinations of 1. - 5.
7. …?
TM-Meeting Wageningen 2011-11-29
Possible reasons
1. Sources for aerosols too low (emissions)
2. Sinks for aerosols too high (deposition, sedimentation) lifetime!
3. Ageing and coagulation too fast in M7 (too few coarse particles)
4. Hygroscopic growth underestimated
5. Optics wrong
6. Combinations of 1. - 5.
7. …?
TM-Meeting Wageningen 2011-11-29
Check of the optics code
• Originally developed by Michael Kahnert (SMHI)• Lookup-tables for {extinction, single-scattering-albedo, asymmetry-parameter}
via– effective refractive index for each log-normal mode in M7
– count mean radius of mode (cmr)
– wavelength (wl)
• Update by Maarten/Joost replacing (cmr & wl) by (cmr/wl) and production of a new lookup-table
TM-Meeting Wageningen 2011-11-29
Lookup-Table Revision
• Extinction coefficients – as a function of mode-radius
– here: for 3 wavelengths and charact. refractive indices of Dust and SO4
– dashed lines: V1; solid lines: V2
TM-Meeting Wageningen 2011-11-29
Check of the optics code
• Originally developed by Michael Kahnert (SMHI)• Lookup-tables for {extinction, single-scattering-albedo, asymmetry-parameter}
via– effective refractive index for each log-normal mode in M7
– count mean radius of mode (cmr)
– wavelength (wl)
• Update by Maarten Krol replacing (cmr & wl) by (cmr/wl) and production of a new lookup-table
• effective refractive index retrieved by mixing rules for internally mixed modes, crucial input:– refractive indices and densities of SO4/BC/POM/Dust/SeaSalt/H2O
SO4 SeaSalt BC Dust POM H2O
refractive index
OPAC* OPAC* OPAC* ECHAM-HAM ECHAM-HAMSegelstein (1981)
densities[kg/m3]
1841 2165 2000 2650 2000 1000
*) Hess et al, 1998
TM-Meeting Wageningen 2011-11-29
Check of the optics code
• Test(s): – update of densities, esp. carbon compounds, both in M7 and optics
– update of optical properties of aerosol components
• Results:– increase of max. 10% for global mean AODs (July 2007)
– change of AAOD not checked (BC)
• Higher sensitivity of AODs to mean particle radii, due to dependence of particle cross section and mass on rg
– redistribution of particle mass and numbers!
TM-Meeting Wageningen 2011-11-29
Possible reasons
1. Sources for aerosols too low (emissions)
2. Sinks for aerosols too high (deposition, sedimentation) lifetime!
3. Ageing and coagulation too fast in M7 (too few coarse particles)
4. Hygroscopic growth too low
5. Optics wrong
6. Combinations of 1. - 5.
7. …?
TM-Meeting Wageningen 2011-11-29
Global mean burdens
• Comparison with “products” that capture observed AOD frequency distribution:– TM5 (year 2006)
– GOCART (year 2006)
– HadGEM2 (year 2006)
– OsloCTM2 (year 2006)
– AeroCom-1 (year 2000)
• Importance ranking (partial AOD):– SO4 (20-40%)
– SeaSalt (15-40%)
– Dust (15-30%)
– POM (10-30%)
– BC ( 0- 5%)
• Main problem: No unique model reference available…
TM-Meeting Wageningen 2011-11-29
Example: SO4 zonal means
sconc
emi wetdep
load
TM-Meeting Wageningen 2011-11-29
Example (cont.): SO4 characteristic times
• lower sink terms in GOCART / OsloCTM• higher chemical production also possible for GOCART / OsloCTM
[d] TM5 AeroCom1 GOCART OsloCTM
burden / emissions
120 110 162 252
burden / deposition
4.63 4.34 5.68 7.90
TM-Meeting Wageningen 2011-11-29
Summary
SO4: • Surface concentrations good (NH-midlat.), loads on the low side• Rather high sink terms (wetdep), esp. in the tropics
SeaSalt:• Despite doubling the emitted mass, the load is still low• Rather high sink terms (wetdep)
Dust:• Loads on the low side• Rather high sink term
POM:• Loads on the low side (SOA!)• Rather high sink terms (wetdep), esp. in the tropics and the NH
BC: • Surface concentrations good, loads on the low side• Rather high sink terms (wetdep), esp. in the tropics
TM-Meeting Wageningen 2011-11-29
Con(cl/f)usion
• Low loads cause low AODs, but presumably the masses can NOT explain the AODs being low by ~50%...
• More likely due to wrong size distributions, so are they correct – in M7 (water uptake / coagulation)??
– in the emissions (radii & masses specified)??
• Size distributions interact with removal processes (deposition, sedimentation).
• Very low fine mode AOD another hint on wrong particle size distribution.
• M7 nucleation/condensation is a very critical process, as seen by the effect of reducing SO2 emissions (H2SO4 precursor).
TM-Meeting Wageningen 2011-11-29
Outlook
• Principle check of removal processes– previous problems known (aan de Brugh, 2010)
– first analysis already done for wetdep
– adaptation of more sophisticated approaches planned (e.g., ECHAM-HAM; Croft et al., ACP, 2010; )
– especially: • wet removal of number and mass individually• usage of current mode radii instead of predefined ones• take into account cloud type for in-cloud scavenging• …
– …
• Check of emission routines and underlying assumptions desirable as well
TM-Meeting Wageningen 2011-11-29
Dust emissions: Introduction
• So far: module by Elisabetta Vignati (presented June 2008)– Offline production of daily emissions using ECMWF meteo fields
• Algorithm is based on Tegen et al. (JGR, 2002) – definition of possible dust uptake areas:
• calculation of the distribution of potential vegetation types (biomes)• non-forest biomes are considered as potential source
– usage of normalised difference vegetation index (NDVI) to derive global fraction of absorbed photosynthetically active radation (FPAR)
– “shrinking” of available uptake area in case of • grass dominated vegetation (FPAR!)• shrub dominated vegetation (FPAR!)• snow cover
– supressing dust uptake when soil moisture exceeds a certain threshold
– vertical particle flux from soil properties (size distribution, alpha) and surface wind stress u* (derived from 10m wind speed)
TM-Meeting Wageningen 2011-11-29
Dust emissions: Offline Implementation
1. Parameters not dependent on time and grid cell o Properties of soil size distribution based on soil population and texture
2. Parameters calculated on daily basiso Snow cover from snow deptho Areas of emissions using potential sources, vegetation, cultivation, lsm,
fpar (and moisture)
3. Parameters calculated on 3 hourly basiso Surface stress from wind speed fluxeso Mapping from emission bins (24) to TM5 modes (2: insoluble
accumulation and coarse)
from presentation by Elisabetta
TM-Meeting Wageningen 2011-11-29
Dust emissions: Input Parameters
• Soil type and size distribution• Preferential dust source areas (paleolakes)• Fraction of absorbed Photosynthetically Active Radiation (FPAR)• Cultivation• Surface roughness length• Vegetation type• Snow depth• Surface wind speed• soil moisture
from Ina TegenECMWF fields
from presentation by Elisabetta
TM-Meeting Wageningen 2011-11-29
Index Vegetation type H/L veg
1 Crops, Mixed Farming L
2 Short Grass L
3 Evergreen Needleleaf Trees H
4 Deciduous Needleleaf Trees H
5 Deciduous Broadleaf Trees H
6 Evergreen Broadleaf Trees H
7 Tall Grass L
8 Desert -
9 Tundra L
10 Irrigated Crops L
11 Semidesert L
12 Ice Caps and Glaciers -
13 Bogs and Marshes L
14 Inland Water -
15 Ocean -
16 Evergreen Shrubs L
17 Deciduous Shrubs L
18 Mixed Forest/woodland H
19 Interrupted Forest H
20 Water and Land Mixtures L
Using Soil ph
Dust emissions: Vegetation types
from presentation by Elisabetta
TM-Meeting Wageningen 2011-11-29
Dust emissions: Input Parameters
TM-Meeting Wageningen 2011-11-29
Dust emissions: Results for 2000
Tegen versus AEROCOM/Ginoux
0
200
400
600
800
1000
1200
1400
1600
1800
OP
EN
OC
EA
N
CA
NA
DA
US
A
LA
TIN
AM
ER
ICA
AF
RIC
A
OE
CD
EU
RO
PE
EA
ST
ER
N E
UR
OP
E
CIS
(FO
RM
ER
US
S
MID
DL
E E
AS
T
IND
IA R
EG
ION
CH
INA
RE
GIO
N
EA
ST
AS
IA
OC
EA
NIA
JA
PA
N
ISL
AN
DS
OC
EA
N
AN
TA
RC
TIC
A
WO
RL
DTegen/TM5 year 2000
ginoux
from presentation by Elisabetta
TM-Meeting Wageningen 2011-11-29
However,
(revised) online version desirable/needed
for EC-Earth/TM5
TM-Meeting Wageningen 2011-11-29
Online dust emissions: What’s new?
• Adaptation to TM5-chem-V3 • Input parameter now in one single NetCDF file• Reformulation of the uplift area as a function of FPAR• Lowered hard constraint of LSM == 100 to LSM > 99• Removed uninitialised parameters, speed optimisation, OpenMP• Identical offline & online version available
TM-Meeting Wageningen 2011-11-29
Online dust emissions: Evaluation
AeroCom-1 median
GISS HadGEM SPRINTARS OsloCTM(year 2006)
MPIHAMv2(year 2006)
dust emissions [Tg/yr]
1126 1110 2972 2596 1420 792
Source: http://aerocom.met.no/
TM-Meeting Wageningen 2011-11-29
Online dust emissions: Evaluation
Tegen versus AEROCOM/Ginoux
0
200
400
600
800
1000
1200
1400
1600
1800
OP
EN
OC
EA
N
CA
NA
DA
US
A
LA
TIN
AM
ER
ICA
AF
RIC
A
OE
CD
EU
RO
PE
EA
ST
ER
N E
UR
OP
E
CIS
(FO
RM
ER
US
S
MID
DL
E E
AS
T
IND
IA R
EG
ION
CH
INA
RE
GIO
N
EA
ST
AS
IA
OC
EA
NIA
JA
PA
N
ISL
AN
DS
OC
EA
N
AN
TA
RC
TIC
A
WO
RL
D
Tegen/TM5 year 2000
ginoux
TM-Meeting Wageningen 2011-11-29
Outlook
• Implementation of soil moisture• Evaluation of load, AOD etc. compared to usage of Ginoux (median
particle size!)• Replacement of input fields by EC-Earth parameters
TM-Meeting Wageningen 2011-11-29
Decadal runs with EC-Earth/TM5
2000-2009/10 and 2025-2035• offline and online simulations with TM5• offline: small pre-processor developed to use EC-Earth CMIP5
output for TM5• online: CMIP5 restart files for EC-Earth/TM5• base case: ERA-Interim driven TM5 simulations 2000-2009• first results for ERA-I (full period) vs. EC-Earth (2000-2002)
TM-Meeting Wageningen 2011-11-29
EC-Earth/TM5: SO4
TM-Meeting Wageningen 2011-11-29
EC-Earth/TM5: Decadal runs
2000-2009/10 and 2025-2035, (2060-70)• offline and online simulations with TM5 and EC-Earth/TM5, resp.• offline: small pre-processor developed to use EC-Earth CMIP5
output for TM5• online: CMIP5 restart files for coupled EC-Earth/TM5• base case: ERA-Interim driven TM5 simulations 2000-2009• first results for ERA-I (full period) vs. EC-Earth (2000-2002)
Outlook• Evaluation of inter-annual variability, extreme events, etc. by
comparison with observations (current climate)• Assessment of climate impact on (aerosol) chemistry by comparing
the two (three) time slice experiments