GEOS-CHEM Activities at NIA
Hongyu Liu
National Institute of Aerospace (NIA)
at NASA LaRC
June 2, 2003
210Pb-7Be-O
3
relationships
210Pb-7Be-O
3
relationships during PEM-West A (Sept-Oct 1991)
210Pb-O
3
Near Asia
Remote Pacific
7Be-O
3
Near Asia
UT
MT
LT
OBSERVATION vs. MODEL
Remote Pacific
210Pb-7Be-O
3
relationships during PEM-West B
210Pb-O
3
Near Asia
Remote Pacific
7Be-O
3
Near Asia
UT
MT
LT
OBSERVATION vs. MODEL
Remote Pacific
210Pb-7Be-O
3
relationships during TRACE-P
210Pb-O
3
< 30oN
> 30oN
7Be-O
3
< 30oN
UT
MT
LT
OBSERVATION vs. MODEL
> 30oN
The effect of clouds on Asian pollution outflow
during TRACE-P
(with Brad Pierce, Jim Crawford, et al.)
• 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)
• ……
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 mm
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?
Simulated dust
April, 2001
• 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.
2001 annual dust simulation
Total Emission: 2500Tg/yr
Tons/km2/yr
500
WETD: 1100Tg/yr
Tons/km2/yr
DRYD: 1400Tg/yr
200
Tons/km2/yr
Avg. Burden: 37Tg
50
mg/m2
2000
IMPROVE sites: extreme Asian dust event in April 2001
16 April, 2001
IMPROVE
Dust PM2.5
0
22 April 2001
4
8 mg/m3
Discrepancies between model and data suggest local sources too strong
IMPROVE
PM2.5 dust
18 west
sites
Model
w/o NA
sources
MODEL
w/ all sources
April 2001
12 east
sites
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-P
ACE-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?
INTEX
Mission
2004
The role of dust: Navajo Mountain, Page, AZ
typical view
16 April 2001
Dust arrives
behind cold
front
SeaWifs
11 April
EPA regional haze rule:
“return Federal
Class I regions to natural
visibility conditions by 2064.”
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.