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GEOS-CHEM Activities at NIA. Hongyu Liu National Institute of Aerospace (NIA) at NASA LaRC June 2, 2003. 210 Pb- 7 Be-O 3 relationships. 210 Pb- 7 Be-O 3 relationships during PEM-West A (Sept-Oct 1991). 210 Pb-O 3. 7 Be-O 3. Near Asia. Remote Pacific. Near Asia. Remote Pacific. UT.
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GEOS-CHEM Activities at NIA Hongyu Liu National Institute of Aerospace (NIA) at NASA LaRC June 2, 2003
210Pb-7Be-O3 relationships during PEM-West A (Sept-Oct 1991) 210Pb-O3 7Be-O3 Near Asia Remote Pacific Near Asia Remote Pacific UT MT LT OBSERVATION vs. MODEL
210Pb-7Be-O3 relationships during PEM-West B 210Pb-O3 7Be-O3 Near Asia Remote Pacific Near Asia Remote Pacific UT MT LT OBSERVATION vs. MODEL
210Pb-7Be-O3 relationships during TRACE-P 210Pb-O3 7Be-O3 < 30oN > 30oN < 30oN > 30oN UT MT LT OBSERVATION vs. MODEL
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: • 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 DRYD: 1400Tg/yr 200 500 Tons/km2/yr Tons/km2/yr WETD: 1100Tg/yr Avg. Burden: 37Tg 50 2000 Tons/km2/yr mg/m2
IMPROVE sites: extreme Asian dust event in April 2001 16 April, 2001 22 April 2001 IMPROVE Dust PM2.5 8 mg/m3 0 4
Discrepancies between model and data suggest local sources too strong IMPROVE PM2.5 dust April 2001 18 west sites 12 east sites Model w/o NA sources MODEL w/ all sources
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 EPA regional haze rule: “return Federal Class I regions to natural visibility conditions by 2064.” 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.