AEROSOL COMPONENT

MODELSan initial comparison

PARISJune 2003

AEROSOL in global models

modeling of aerosol climatic impacts is done

- at coarse resolution (ca 30x30)

- in many individual steps- individually by aerosol type

many processespossibilities for errors

modeling of aerosol climatic impacts is done- at coarse resolution (ca 3*3deg)- in many individual steps- individually by aerosol type

many processespossibilities for errors

AOT data-sets

• satellites:

– MODIS– TOMS– POLDER– AV. 2Ch– AV. 1Ch

• ground:

– AERONET

yearly avg.

testing models - PAST

• monthly statistics• 8 models !

0

0.05

0.1

0.15

0.2

0.25

component combined aot (0.55um)

EC

GO

MI

GI

CC

GR

UL

NC

MO

TO

A,n

A,g

PO

Aero

---Models---- Data

best satellite AERONET

AOT

testing models - PAST • Consistency? … just look at global averages for mass (turquoise background) and

opt.depth (brown background) … and differences in mass aot !

00.5

11.5

22.5

33.5

4

org. carbon mass (mg/m2)

ECGOMIGICCGRULHANC

0

0.01

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0.06

dust aot (0.55um)

ECGOMIGICCGRULHANC

01020304050607080

dust mass (mg/m2)

ECGOMIGICCGRULHANC

0

0.005

0.01

0.015

0.02

0.025

0.03

org. carbon aot (0.55um)

ECGOMIGICCGRULHANC

0

0.1

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blk carbon mass (mg/m2)

ECGOMIGICCGRULHANC

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

blk carbon aot (0.55um)

ECGOMIGICCGRULHANC

01020304050607080

sea-salt mass (mg/m2)

ECGOMIGICCGRULHANC

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sea-salt aot (0.55um)

ECGOMIGICCGRULHANC

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sulfate mass (mg/m2)

ECGOMIGICCGRULHANC

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0.01

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0.07

sulfate aot (0.55um)

ECGOMIGICCGRULHANC

Dust Sulfate Sea-Salt org. Carbon black Carbon

first Impressions

• Models agree on – high carbon in central Africa (~ 60%)– high sulfate for Europe and E.Asia ( ~ 45%)– dominant sea-salt in mid-latitudes of the SH– dominant dust over N.Africa and central Asia

• Models disagree on– source strength for dust and for biomass burning– carbon contrib. for tropics and over urban regions– transport (contributions in off-source regions)– sea-salt contributions over oceans

Relative Model Tendencies

• ECHAM4 strong du- seasonality, low ss and bc MEE, rh-sensitivity

• GOCART strong transport, strong du, strong oc-, bc- seasonality

• MIRAGE strong su (+oc), weak on trop.sources, high lat. bias

• GISS low on mass (except for su), strong du MEE

• CCSR strong oc-, bc-, du- seasonality (+ sources), weak transport• Grantour lowest oc/bc -mass ratios, strong ss MEE and opt.depth• ULAQ strongest su-, oc- urban sources, weak transport (bc)

• NCAR weak bc, low oc und bc MEE, high ss MEE

• HadHam strong su- seasonality, weak on bc

su -sulfate, du -dust, ss -seasalt, oc -org.carbon, bc -black carbon

Quantification- local -

• % hits vs AERONET -aot• Yearly average: +/- 20%• Season-phase: +/- 1 month• Season-strength: +/- 50%

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s-phase s-strength yr.avg s-p,s-s s-p,s-s,av[%]

ECGOMIGICCGRULMO

20 AERONET sites

MODIS aots are usually larger than aots fromAERONET (..mainly due to snow in winter)

Quantification- regional -

• % hits vs MODIS/TOMS- aot• Yearly average: +/- 20%• Seasonality phase : +/- 1

month (for 3mo-avg max)

01020

30405060

708090

sea.-phase average av+ph [%]

ECGOMIGICCGRUL

evaluated regions

• most models predict lower aots than MODIS/TOMS

• discrepancies are largest in remote regions (sea-salt size?)

• but larger simulated aots for Europe (old outdated sources?)

TOPICS

• Compare size assumptions for aerosol types• reduce differences in the MASS to AOT conversion

• Remove size ambiguity from rel.hum fields?• prescribe relative humidity fields (ECWMF) in aot conversions

• Aerosol vertical distribution and lifetime?• compare for simulations with identical sources / sizes

• What is known about removal processes?• compare for simulations with identical sources / sizes

• Is the chemistry (gas to particle) correct?• compare results with and without chemistry