SOME CHEMICAL PROBLEMS SOME CHEMICAL PROBLEMS IN ATMOSPHERIC CHEMISTRY MODELS IN ATMOSPHERIC CHEMISTRY MODELS Daniel J. Jacob with in order of appearance: Rokjin Park, Colette L. Heald (now at UC Berkeley), Tzung-May Fu, Paul I. Palmer (now at U. Leeds), Dylan B. Millet, Rynda C. Hudman, Noelle E. Selin, Christopher D. Holmes …and funding from EPRI, EPA, NSF, NASA
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SOME CHEMICAL PROBLEMS IN ATMOSPHERIC CHEMISTRY MODELS
SOME CHEMICAL PROBLEMS IN ATMOSPHERIC CHEMISTRY MODELS. Daniel J. Jacob. with in order of appearance: Rokjin Park, Colette L. Heald (now at UC Berkeley), Tzung-May Fu, Paul I. Palmer (now at U. Leeds), Dylan B. Millet, Rynda C. Hudman, Noelle E. Selin, Christopher D. Holmes. - PowerPoint PPT Presentation
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SOME CHEMICAL PROBLEMS SOME CHEMICAL PROBLEMS IN ATMOSPHERIC CHEMISTRY MODELSIN ATMOSPHERIC CHEMISTRY MODELS
Daniel J. Jacob
with in order of appearance: Rokjin Park, Colette L. Heald (now at UC Berkeley), Tzung-May Fu, Paul I. Palmer (now at U. Leeds), Dylan B. Millet, Rynda C. Hudman, Noelle E. Selin, Christopher D. Holmes
…and funding from EPRI, EPA, NSF, NASA
GEOS-Chem GLOBAL 3-D CHEMICAL TRANSPORT MODELGEOS-Chem GLOBAL 3-D CHEMICAL TRANSPORT MODEL
• Driven by assimilated meteorological data from NASA Global Modeling and Assimilation Office (GMAO) with 3-6 hour resolution
• Horizontal resolution 1ox1o to 4ox5o , ~50 vertical layers
• Applied to wide range of problems: tropospheric oxidants, aerosols, CO2, methane, hydrogen, mercury, exotic species…by over 20 groups in N. America, Europe, Australia
• Flagship tropospheric ozone-aerosol simulation includes ~120 coupled species, ~500 chemical reactions
• Serves grander purposes: (1) boundary conditions for EPA CMAQ regional model , (2) global chemical data assimilation at GMAO, (3) effects of climate change through interface with GISS GCM, (4) construction of Earth system model through NASA/GMI
OUR FIRST ORGANIC CARBON (OC) SIMULATION OUR FIRST ORGANIC CARBON (OC) SIMULATION FOR THE UNITED STATESFOR THE UNITED STATES
IMPROVE obs (1998)
U.S. source:2.7 Tg yr-1
Park et al. [2003]annual
10%terpenes
FIRST MASS CONCENTRATION MEASUREMENTSFIRST MASS CONCENTRATION MEASUREMENTSOF OC AEROSOLS IN FREE TROPOSPHEREOF OC AEROSOLS IN FREE TROPOSPHERE
ACE-Asia aircraft data over Japan (April-May 2001)
Observed (Huebert)GEOS-Chem (Chung & Seinfeld for SOA)
Observed (Russell)
OC/sulfate ratio
Heald et al. [2005]
Chung and Seinfeld scheme:,T OC
VOC SOG SOA • Observations show 1-3 g m-3 background;model too low by factor 10-100
ITCT-2K4 AIRCRAFT CAMPAIGN OVER EASTERN U.S. ITCT-2K4 AIRCRAFT CAMPAIGN OVER EASTERN U.S. IN JULY-AUGUST 2004 IN JULY-AUGUST 2004
Data filtered againstfire plumes (solid)and unfiltered (dotted)
Model source attribution
TotalBiomass burningAnthropogenicBiogenic SOA
Heald et al., in prep.
CORRELATION OF OBSERVED FREE TROPOSPHERIC WSOCCORRELATION OF OBSERVED FREE TROPOSPHERIC WSOCWITH OTHER CHEMICAL VARIABLES IN ITCT-2K4WITH OTHER CHEMICAL VARIABLES IN ITCT-2K4
No single variable gives R > 0.37, but toluene bivariate correlations with sulfate, acetic acid, and HNO3 give R > 0.7. No correlation with isoprene oxidation products
Heald et al., in prep.Suggest aqueous-phase mechanism involving aromatics
ALTERNATE MECHANISM FOR SOA FORMATION:ALTERNATE MECHANISM FOR SOA FORMATION:AQUEOUS-PHASE OXIDATION AND POLYMERIZATION OF DICARBONYLSAQUEOUS-PHASE OXIDATION AND POLYMERIZATION OF DICARBONYLS
CHOCHO
Isoprene
350 TgC/yr * (Y ~ 4.5%)
= 16 TgC/yr
Aromatics
20 TgC/yr * (Y~ 20%)
= 4 TgC/yr
Monoterpenes
100 TgC/yr * (Y ~ 0.09%) = 0.9 TgC/yr
Oxidation by OH
Photolysis
Deposition
~ 1.3 h
CH(OH)2CH(OH)2
OxidationPolymerization
AQUEOUS PHASE
Liggio et al. [2005],Lim et al. [2005],Hastings et al. [2005]Kroll et al. [2005]
H* = 4x105 M atm-1glyoxal
MODEL REPRESENTATION OF AQUEOUS-PHASE SOA FORMATION MODEL REPRESENTATION OF AQUEOUS-PHASE SOA FORMATION USING REACTION PROBABILITY USING REACTION PROBABILITY APPLIED TO GLYOXALAPPLIED TO GLYOXAL
Liggio et al. [2005]
0.56 ppb
0.28 ppb
Z (
km)
Z (
km)
GEOS-Chem glyoxal and GEOS-Chem glyoxal and methylglyoxal in surface air (July)methylglyoxal in surface air (July)
Production: isoprene, monoterpene, aromatics
Loss: photolysis, oxidation
No aerosol uptake, dry/wet deposition yet
GLYX [ppb] at 0E
MGLY [ppb] at 0E
Tzung-May Fu, Harvard
OXYGENATED VOCs OXYGENATED VOCs OVER TROPICAL OVER TROPICAL PACIFIC (PEM-PACIFIC (PEM-
TROPICS B DATA)TROPICS B DATA)SH
NH
Singh et al. [2001]
Methanol and acetone arethe principal contributors
GLOBAL MODEL BUDGET OF METHANOL (Tg yrGLOBAL MODEL BUDGET OF METHANOL (Tg yr-1-1))with (in parentheses) ranges of previous budgets from Singh et al. [2000],
Heikes et al. [2002], Galbally and Kirstine [2003], Tie et al. [2003]
GLOBAL GEOS-CHEM BUDGET OF ACETONE (Tg yrGLOBAL GEOS-CHEM BUDGET OF ACETONE (Tg yr-1-1))from Jacob et al. [2002] with photolysis update from Blitz et al. [2004]with photolysis update from Blitz et al. [2004]
OCEANIC SOURCE OF ACETONE IN MODELOCEANIC SOURCE OF ACETONE IN MODELNEEDED TO MATCH OBSERVATIONS OVER S. PACIFICNEEDED TO MATCH OBSERVATIONS OVER S. PACIFIC
How to explain thepervasive 200 pptv acetone background?Tzung-May Fu (Harvard)
HCHO COLUMN DATA FROM OMI SATELLITE INSTRUMENTHCHO COLUMN DATA FROM OMI SATELLITE INSTRUMENT
Thomas Kurosu (Harvard/SAO) and Dylan Millet (Harvard)
July 2005
SPACE-BASED MEASUREMENTS OF HCHO COLUMNSSPACE-BASED MEASUREMENTS OF HCHO COLUMNSAS CONSTRAINTS ON VOLATILE ORGANIC COMPOUND AS CONSTRAINTS ON VOLATILE ORGANIC COMPOUND
(VOC) EMISSIONS(VOC) EMISSIONS
VOC HCHOOxidation (OH, O3, NO3)
several steps
hnm), OH
lifetime of hours
340 nm
VOCs important as • precursors of tropospheric ozone• precursors of organic aerosols• sinks of OH
Vegetation Anthropogenic Biomass burning ~1000 ~200 ~100 Tg C yr-1
TIME-DEPENDENT HCHO YIELDS FROM VOC OXIDATIONTIME-DEPENDENT HCHO YIELDS FROM VOC OXIDATION
Palmer et al, [2006]
High HCHO signal from isoprene with little smearing, weak and smeared signal from terpenes; GEOS-Chem yields from isoprene may be too low by 10-40% depending on NOx
Box model simulations with state-of-science MCM v3.1 mechanism
methylbutenol
HCHO YIELDS FROM ISOPRENE OXIDATIONHCHO YIELDS FROM ISOPRENE OXIDATION
Palmer et al. [2003], Millet et al. [2006]
INTEX-A observations imply a per carbon yield of 0.32 ± 0.1
HCHO vs. isoprene columnsin INTEX-A
observed
H
CH
O,
1016
cm
-2
ISOP, 1016 cm-2
m = 3.3
m = 3.5
GEOS-Chem
Sensitivity to peroxide recycling(standard model assumes recycling)
UltimateHCHO yield
RADICAL CHEMISTRY IN UPPER TROPOSPHERE:RADICAL CHEMISTRY IN UPPER TROPOSPHERE:INTEX-A aircraft data over southeast U.S. (Jul-Aug 04)INTEX-A aircraft data over southeast U.S. (Jul-Aug 04)
NOxO3 HO2
OH
Black: observations by Cohen (NO2), Avery (ozone), Brune (HO2 and OH)Red: standard model simulation Green: model simulation with 4x lightning
Fixing NOx (and ozone!) results in 3x overestimate of OH in upper troposphere;IF we could fix OH, the NOx and ozone underestimates would fix themselves…
Hudman et al. (in prep.)
BrOBrOxx CHEMISTRY IN TROPOSPHERE CHEMISTRY IN TROPOSPHERE
due to Arctic BL spring bloom
Satellites observe 0.5-2pptv BrO in excess of what stratospheric models can explain.
Yang et al. [2005] global model including bromocarbon oxidation/photolysis and sea salt debromination
Tropospheric BrO ?
Significant consequences for tropospheric ozone and NOx budgets
MERCURY IN THE ATMOSPHEREMERCURY IN THE ATMOSPHERE
Hg(0)(gas)
Hg(II)(gas)Oxidation
OH, O3, Br(?)
TOTAL GASEOUS MERCURY (TGM)
DRY AND WET DEPOSITION
REACTIVE GASEOUS MERCURY (RGM)
RELATIVELY INSOLUBLE
ATMOSPHERIC LIFETIME: ABOUT 1 YEAR
TYPICAL LEVELS: 1.7 ng m-3
LIFETIME: DAYS TO WEEKS
TYPICAL LEVELS: 1-100 pg m-3
ReductionPhotochemical aqueous (?)
Hg(II)(aqueous)
Hg(P)(solid)
ECOSYSTEM INPUTS
VERY SOLUBLE
EMITTED BY COAL-EMITTED BY COAL-FIRED POWER PLANTSFIRED POWER PLANTS
LARGE UNCERTAINTY IN ATMOSPHERIC Hg CHEMISTRYLARGE UNCERTAINTY IN ATMOSPHERIC Hg CHEMISTRY
Hg(II) 16d
Hg(II) 20maq
TGM 0.79y
(parenthetical reactions not in model)
Large discrepancies in reported rates!
8.7(±2.8) x 10-14 Sommar et al., AE 20019.0(±1.3) x 10-14 Pal & Ariya, ES&T 2004much slower Calvert & Lindberg, AE
2005
0Hg +OHk [cm3 s-1]
3(±2) x 10-20 Hall, WASP 19951.7 x 10-18 Iverfeldt & Lindqvist, AE 198
03Hg +O
k [cm3 s-1]
0Hg120d
Deposition
In standard GEOS-Chem, 80% ofHg(0) oxidation is by OH; 60% of produced Hg(II) is reduced back to Hg(0) photochemically in clouds
RAPID CONVERSION OF Hg(0) to Hg(II) IN ARCTIC SPRINGRAPID CONVERSION OF Hg(0) to Hg(II) IN ARCTIC SPRINGObservation ofObservation of Mercury Depletion Events (MDEs)Mercury Depletion Events (MDEs)
Hg0 HgBr HgBrX
1
Br Br, OH
T
2
3
Spitzbergen: Sprovieri et al., ES&T 2005
MDEs correlate with ODEs and reactive halogens (up to 30pptv BrO).
Goodsite et al., ES&T 2005
EVIDENCE FOR OXIDATION OF Hg(0) BY Br EVIDENCE FOR OXIDATION OF Hg(0) BY Br IN MARINE BOUNDARY LAYERIN MARINE BOUNDARY LAYER
Jaffe et al [2005]; Selin et al. [2006]
ObservationsGEOS-Chem (OH,O3)
Residual diurnal cycle of Hg(0) observed at Okinawa in April
Consistent with Br release fromBr2 or HOBr at sunrise
COULD Br BE THE MISSING GLOBAL Hg(0) OXIDANT?COULD Br BE THE MISSING GLOBAL Hg(0) OXIDANT?
Br mixing ratio (Yang et al., 2005) Hg0 Lifetime
Holmes et al., GRL 2006
Global lifetime of Hg(0) against oxidation by Br: 0.6 y (range 0.2-1.6 y); Compare to observational constraint of ~1 y for Hg lifetime against deposition