GEOS-CHEM Activities at NIA

Hongyu Liu

National Institute of Aerospace (NIA)at NASA LaRC

June 2, 2003

210Pb-7Be-O3 relationships

210Pb-7Be-O3 relationships during PEM-West A (Sept-Oct 1991)

Near Asia Remote Pacific Remote PacificNear Asia

210Pb-O37Be-O3

UT

MT

LT

OBSERVATION vs. MODEL

210Pb-7Be-O3 relationships during PEM-West B

210Pb-O37Be-O3

UT

LT

MT

OBSERVATION vs. MODEL

Near Asia Remote Pacific Near Asia Remote Pacific

210Pb-7Be-O3 relationships during TRACE-P

< 30oN > 30oN < 30oN > 30oN

210Pb-O37Be-O3

UT

LT

MT

OBSERVATION vs. MODEL

• RAQMS (regional) & GEOS-CHEM (global);• LaRC/UW Regional Air Quality Modeling System (RAQMS) jointly developed by NASA Langley and Univ Wisconsin [Pierce et al., 2003]; • Fast-J2 scheme recently implemented in RAQMS• Cloud and trace gas distributions• Cloud optical depth (model vs. satellite)• ……

The effect of clouds on Asian pollution outflowduring TRACE-P

(with Brad Pierce, Jim Crawford, et al.)

Intercontinental transport, Continental outflow, and Chemical processing of aerosols

with GEOS-CHEM

Duncan Fairlie*

Rokjin Park

Daniel Jacob

Dept. Earth and Planetary Sciences

Harvard University

*Also NASA Langley Research Center, Hampton, VA

2 June 2003

Project Goals:(1) Assess the impact of intercontinental

transport of mineral dust on aerosol concentrations in North America

(2) Assess the global impact of heterogeneous uptake on mineral dust on SO4

= production and NOy partitioning

(3) Quantify export of aerosols and precursors from the North America, and relate to sources.

Aerosol Module in GEOS-CHEM•

Aerosol Module: Based on GOCART (Chin et al., 2002): SO4, sea salt, dust, OC, EC.• Added NH3 (Adams et al., 1999), H2SO4-HNO3-NH3-H2O thermodynamics (Nenes et al., 1998). Rokjin Park

• Dust module:• Mobilization: Ginoux et al. (2001) • Dry deposition: Zhang et al. (2000) • Wet deposition: Liu et al. (2001)• Dust size bins: 0.1-1.0, 1.0-1.8, 1.8-3.0, 3.0-6.0 m radius.

Full coupling with oxidant-aerosol chemistry: gas-aqueous sulfur oxidation; HNO3/nitrate partitioning; heterogeneous uptake of N2O5, NO2, NO3, HO2; impact on photolysis rates. •

1. How much does Asian dust contribute to

concentrations over North America?

• Use GEOS-CHEM to quantify intercontinental transport

of dust to the U.S.

• Evaluate the model with data from the IMPROVE network, AERONET observations, TRACE-P and ACE-Asia data, and MODIS AOD.

• Assess the model against the constraints of observations.

Simulated dustApril, 2001

2001 annual dust simulation

Total Emission: 2500Tg/yr DRYD: 1400Tg/yr

WETD: 1100Tg/yr Avg. Burden: 37Tg

200500

50 2000mg/m2

Tons/km2/yr

Tons/km2/yr

Tons/km2/yr

IMPROVE sites: extreme Asian dust event in April 2001

0 4 8 g/m3

16 April, 2001 22 April 2001

IMPROVEDust PM2.5

IMPROVEPM2.5 dust

MODELw/ all sources

Modelw/o NA sources

18 westsites

12 east sites

Discrepancies between model and data suggest local sources too strong

April 2001

2. Evaluate global impact of uptake of SO4

= and NO3- on dust

• GEOS-CHEM - fully coupled aerosol-gas simulation.

• Uptake of HNO3, SO2, H2SO4 on dust.

• Carry alkalinity as a tracer to limit uptake

• Distinguish alkalinity differences at source.

• Use obs. to assess simulation, and constrain sources.

TRACE-PACE-Asia

3. Impact of continental outflow on the

global atmosphere:Key science objective of INTEX: What is the aerosol outflow from N. America, and

how does it relate to surface sources? What are the outflow mechanisms, and how do

they differ for aerosols, gases?

INTEXMission2004

The role of dust: Navajo Mountain, Page, AZ typical view 16 April 2001

EPA regional haze rule: “return Federal Class I regions to naturalvisibility conditions by 2064.”

Dust arrivesbehind coldfront

SeaWifs 11 April

Chemical modification due to uptake of HNO3, SO2, H2SO4 on mineral dust

• Change global NOx/HNO3 partitioning.

and impact O3 budget.

• Speed up SO2 conversion to sulfate, and impact the SO4

= lifetime.

• Make dust hygroscopic and promote additional aqueous surface reactions, e.g. SO2, N2O5

• Shift aerosol sizes to larger particles. Impact radiative properties.