SIMULATING AMAZONIAN BIOGENIC EMISSIONS AND

TROPOSPHERIC CHEMISTRY USING A GEOS-CHEM NESTED GRIDMichael Barkley (U. Leicester, UK) + 17 others

Motivation:

Use model & satellite HCHO columns to constraint Amazonian isoprene emissions

Model version:v8-03-01

Meteorology:GEOS-5 1/2 lat x 2/3 lon

CONTRASTING ISOPRENE EMISSIONS INVENTORIES

MEGAN ( CANOPY-SCALE )

• E = EF × Activity Factors

• Use MODIS LAI for seasonal changes in vegetation

LPJ-GUESS ( LEAF-SCALE )

• E = J × ε × α × fi ( ≈ photosynthesis )

• Use LPJ-GUESS DVM for seasonal changes in vegetation

LPJ ( CRU )CRU meteorologyArneth et al. 2007,2010

MEGAN-Hybrid5-layer canopy model

Guenther et al. 1995,1999,2006

MEGAN-PCEEAParameterized model

Guenther et al. 2006

LPJ ( GC )GEOS-5 meteorology

Arneth et al. 2007,2010

CHEMICAL MECHANISM BOUNDARY LAYER MIXING

1) Standard 43 tracers

2) Caltech 56 tracers

1) Full mixing

2) Non-local

Compare with MEGAN-MOHYCANMuller et al. 2008 (uses ECMWF + detailed canopy model)

T2M & PAR PRECTOT, SWGNET & T2M

w & w/o OH recycling

Climate Research Unit @ UEA, UK

WHY WE NEED TOP-DOWN

ISOPRENE EMISSION ESTIMATES !

2005 2006 2007 2008

Hybrid 174 154 152 135

PCEEA 162 140 138 119

LPJ (GC) 73 75 69 73

LPJ (CRU ) 102 90 - -

MOHYCAN 102 100 - -

Units = Tg C

MODEL TYPICALLY OVERESTIMATES OBSERVED HCHO COLUMNSHybrid PCEEA Hybrid' LPJ(CRU) LPJ(GC) Hybrid PCEEA Hybrid' LPJ(CRU) LPJ(GC)

Submitted to JGR –with Editor for decision

Simulations based on Caltech chemical mechanism and with full boundary layer mixing

EXTRA

THE DIURNAL CYCLE OF ISOPRENE OXIDATION CHEMISTRY

HOW DOES THE MODEL PERFORM?

Hybrid (standard chemical scheme, full PBL mixing)

PCEEA (standard chemical scheme, full PBL mixing)

Hybrid (Caltech chemical scheme, non-local PBL mixing, inc OH-recycling)

Hybrid x 0.635 (standard chemical scheme, full PBL mixing)

SCIAMACHY vertical column + 1 sd

Truth: Troffee ground based measurements ~60W 2.6S NNW Manaus

COMPARISON WITH GABRIEL

OBSERVATIONS