Implementation of Sulfate and SeaSalt Aerosol Microphysics in

Implementation of Sulfate and Sea-Salt Aerosol Microphysics in GEOS-Chem Win Trivitayanurak & Peter Adams Carnegie Mellon University 3 rd GEOS-Chem Users’ Meeting April 11, 2007

Radiative Forcing Estimates Global-average estimates for 2005, relative to 1750 +2. 6 W/m 2 IPCC (2007) +1. 6 W/m 2 -1. 2 W/m 2 Level of scientific understandin g Must improve aerosol indirect effect estimate! Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 2

Improving Aerosol Microphysics GISS GCM-II’ • Produce its own meteorology • Cannot predict at a specific time GEOSCHEM • Driven by assimilated meteorology • Good for predicting at specific times for comparison with observations Microphysics Climate change & Forcing estimate purpose Aerosol model evaluation purpose Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 3

Size-resolved Microphysics • TOMAS (Tw. O-Moment Aerosol Sectional microphysics algorithm) [Adams and Seinfeld, 2002] – Moments = 1) aerosol number and 2) aerosol mass – 30 bins segregated by dry mass per particle – Size range is about 10 nm – 10 μm Size Distribution N 6 N 7 … N 4 N 5 N 1 N 2 N 3 Na. Cl SO 42 - Na. Cl N 30 SO 42 - … Implementation Aerosol Microphysics in GEOS-Chem Dp Win T. 11/4/07 4

TOMAS processes – Coagulation – Condensation/ evaporation – Nucleation – In-cloud sulfur oxidation – Size-resolved dry deposition – Size-resolved wet deposition Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 5

TOMAS Status • Species: Number, SO 42 -, Sea-salt • Advection – Problem: TPCORE/ PPM parabolic interpolation artificially grows/shrinks particles – Fixed (see me for detail) • Convection – Negative entrainment at some time steps Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 6

TOMAS Status • Emission – Sulfate: Same total, apply size distribution – Sea-salt: Clarke et al (2006) parameterization – Number: calculated from emitted mass and assumed size distribution • Nucleation : Binary nucleation (H 2 SO 4 -H 2 O) • Aqueous oxidation of sulfate – Distribute over activated size range using condensation/evaporation algorithm Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 7

TOMAS Status • Wet deposition – In-cloud: • Activated particles are removed same way as the original rainout (1 st order loss). • Interstitial particles are assumed inert. – Below-cloud: Apply size-resolved washout rate Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 8

TOMAS Status • Dry deposition – Size-resolved scheme of Zhang et al (2001) as in later versions of G-C 10 Deposition Velocity (cm s-1) 1 New Original 0. 1 0. 01 0. 1 1 10 Dry particle diameter (mm) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 9

Aerosol Prediction from TOMAS Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 10

Model Results Total Number Concentration (cm-3) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 11

Model Results Notice the scale! CCN(0. 2%) (cm-3) Total Number Concentration (cm-3) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 12

Model Results Pressure [mbar] Nucleation region Tropical convection CCN removed with rain Emitted as well as grown into CCN sizes Heavy pollution region Latitude Total Number Concentration (cm-3) Latitude CCN(0. 2%) (cm-3) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 13

Model Results Remote marine, Southern Ocean Industrial region, China Nucleated particles Sulfate primary emission Grow by condensation as they descend Cloud processing From cloud top down to surface Bimodal dist. Sea-salt emission -Significant mass (Larger particle) -Fewer numbers. Number Size Distribution d. N/d. Log. Dp (cm-3) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 14

L 19 Model Results Remote marine, Southern Ocean L 17 L 10 L 1 Number Size Distribution d. N/d. Log. Dp (cm-3) Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 15

Upcoming Tasks & Challenges • Introducing 30 -bin OC, EC, and dust • Running 2 x 2. 5 memory need for (30*(n+2)) aerosol tracers, where n=number of mass species • OR … Running nested grid over ACE-Asia domain? • Comparing aerosol prediction with number size distribution measured from ACE-Asia Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 16

Question? Check out my poster about … • Comparison with Heintzenberg marine aerosol data • Inter-model comparison : G-C, GISS GCM-II’ and GLOMAP Implementation Aerosol Microphysics in GEOS-Chem Win T. 11/4/07 17