HYSPLIT Modelingin Phase II of the
EMEP Mercury Modeling Intercomparison Study
Dr. Mark Cohen Physical Scientist
NOAA Air Resources LaboratorySilver Spring, Maryland
Presentation at theExpert Meeting on
Mercury Model Comparison MSC-East, Moscow, Russia
April 15-16, 2003
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N
Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (0) emitted per year)Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Standard SourceLocations forInterpolation
Is the source’s impact on any given receptor proportional to its emissions?(for the same emissions speciation)
Impact of5 gram/hrsource
?= 5 x
Impact of1 gram/hrsource
Source
RECEPTOR
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N
Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (0) emitted per year)Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Standard SourceLocations forInterpolation
Spatial interpolation
RECEPTOR
Impacts fromSources 1-3are ExplicitlyModeled
2
1
3
Impact of source 4 estimated fromweighted average of impacts of nearbyexplicitly modeled sources
4
1E-4 1E-3 1E-2 1E-1
Explicitly Modeled Transfer Coefficient
1E-4
1E-3
1E-2
1E-1
Inte
rpol
ated
Tra
nsfe
r C
oeff
icie
nt
Lake Erie
Lake Michigan
Lake Superior
Lake Huron
Lake Ontario
Interpolated =Modeled
Comparison of interpolated transfer coefficients to the Great Lakes with explicitly modeled transfer
coefficients for 2378 TCDD and OCDD
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N
Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (0) emitted per year)Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Standard SourceLocations forInterpolation
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Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (II) emitted per year)
Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Transfer Coefficients for Hg are strongly influenced by the “type” of Hg emitted
[Hg(II) has much greaterlocal impacts than Hg(0)]
N
Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (p) emitted per year)
Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
“Chemical Interpolation”
Impact ofSourceEmitting30% Hg(0)50% Hg(II)20% Hg(p)
=
Source
RECEPTOR
Impact of Source Emitting Pure Hg(0)0.3 x
Impact of Source Emitting Pure Hg(II)0.5 x
Impact of Source Emitting Pure Hg(p)0.2 x
+
+
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Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (Mixture 2*) emitted per year)
Fraction of Mercury Emissions Deposited in Lake Superior
* Components of Mixture 2 20% Hg(0) 60% Hg(II) 20% Hg(p)
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
N
Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (Mixture 1*) emitted per year)
Fraction of Mercury Emissions Deposited in Lake Superior
* Components of Mixture 1 50% Hg(0) 30% Hg(II) 20% Hg(p)
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Source 1
Source 2
Intersectionof plumesfrom thetwo sources
Do the emissions from one source affect the fate and transport of emissions from another source?
If interaction is important,then sources not independent,and Eulerian approach is needed
• Hg is present at extremely trace levels in the atmosphere
• Hg won’t affect meteorology (can simulate meteorology independently,
and provide results to drive model)
• Most species that complex or react with Hg are generally present at much higher concentrations than Hg
• Other species (e.g. OH) generally react with many other compounds than Hg, so while present in trace quantities, their concentrations cannot be strongly influenced by Hg
•The current “consensus” chemical mechanism (equilibrium + reactions) does not contain any equations that are not 1st order in Hg
• Wet and dry deposition processes are generally 1st order with respect to Hg
Why might the atmospheric fate of mercury emissions be essentially linearly independent?
gas-liquid eqlbrm Hg(0)(aq) = K1 * Hg(0)(gas) K1 = 1.1E-01 molar/atmgas-liquid eqlbrm HgCl2(aq) = K2 * HgCl2(gas) K2 = 1.4E+06 molar/atmgas-liquid eqlbrm Hg(OH)2(aq) = K3 * Hg(OH)2(gas) K3 = 1.2E+04 molar/atmgas-liquid eqlbrm O3(aq) = K4 * O3(gas) K4 = 1.1E-02 molar/atmgas-liquid eqlbrm SO2(aq) = K5 * SO2(gas) K5 = 1.2E+00 molar/atmgas-liquid eqlbrm HCl(aq) = K6 * HCl(gas) K6 = 1.1E+00 molar/atmgas-liquid eqlbrm Cl2(aq) = K7 * Cl2(gas) K7 = 7.6E-02 molar/atmgas-liquid eqlbrm H2O2(aq) = K8 * H2O2(gas) K8 = 7.4E+04 molar/atm
aq phase eqlbrm HgCl2 (aq) <--> Hg2+ + 2 Cl-1 K9 = 1.0E-14 molar*molaraq phase eqlbrm Hg(OH)2 (aq) <--> Hg2+ + 2 OH-1 K10 = 1.0E-22 molar*molaraq phase eqlbrm HCl(aq) <--> H+ + Cl-1 K11 = 1.7E+06 molaraq phase eqlbrm Cl2 (aq) <--> HOCl + Cl-1 + H+ K12 = 5.0E-04 molar*molaraq phase eqlbrm HOCl <--> OCl-1 + H+ K13 = 3.2E-08 molaraq phase eqlbrm SO2 (aq) + H2O2 (aq) <--> SO4-2 + 2 H+ K14 = very fast titrationaq phase eqlbrm SO2 (aq) + H2O <--> HSO3-1 + H+ K15 = 1.2E-02 molaraq phase eqlbrm HSO3-1 <--> SO3-2 + H+ K16 = 6.6E-08 molaraq phase eqlbrm Hg+2 + SO3-2 <--> HgSO3 K17 = 5.0E+12 1/molaraq phase eqlbrm HgSO3 + SO3-2 <--> Hg(SO3)2-2 K18 = 2.5E+11 1/molar
gas phase rxn Hg(0) (g) + O3 (g) --> Hg(II) (g) R01 = 3.0E-20 cm3 / molec - secgas phase rxn Hg(0) (g) + HCl (g) --> HgCl2 (g) R02 = 1.0E-19 cm3 / molec - secgas phase rxn Hg(0) (g) + H2O2 (g) --> Hg(OH)2 (g) R03 = 8.5E-19 cm3 / molec - secgas phase rxn Hg(0) (g) + Cl2 (g) --> HgCl2 (g) R04 = 4.0E-18 cm3 / molec - sec
aq phase rxn Hg(0) (aq) + O3 (aq) --> Hg+2 R05 = 4.7E+07 1/molar-secaq phase rxn Hg(0) (aq) + OH-1 (aq) --> Hg+2 R06 = 2.0E+09 1/molar-secaq phase rxn HgSO3 (aq) --> Hg(0) (aq) R07 = 1.1E-02 1/secaq phase rxn Hg(II) (aq) + HO2 (aq) --> Hg(0) (aq) R08 = 1.7E+04 1/molar-secaq phase rxn Hg(0) (aq) + HOCl (aq) --> Hg+2 R09 = 2.1E+06 1/molar-secaq phase rxn Hg(0) (aq) + OCl-1 --> Hg+2 R10 = 2.0E+06 1/molar-secaq phase rxn Hg(II) (aq) <--> Hg(II) (soot) R11 = 9.0E+02 liters/gram; t = 1/hour
Chemical Equilibrium and ReactionScheme for Atmospheric Mercury
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Overalll Transfer Coefficient (fraction deposited)
500 0 500 1000 Miles
500 0 500 1000 Kilometers
(grams of total Hg deposited per year / grams of Hg (0) emitted per year)Fraction of Mercury Emissions Deposited in Lake Superior
0 - 0.0000070.000007 - 0.000010.00001 - 0.000020.00002 - 0.000040.00004 - 0.000070.00007 - 0.00010.0001 - 0.00020.0002 - 0.00040.0004 - 0.00070.0007 - 0.0010.001 - 0.0020.002 - 0.0040.004 - 0.0070.007 - 0.010.01 - 0.020.02 - 0.040.04 - 0.070.07 - 0.1
Standard SourceLocations forInterpolation
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measured TGMmodeled Hg(0) + RGMmodeled Hg(0)
Neuglobsow 1999 (with background)
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entr
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n (n
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measured TGM
modeled Hg(0) + RGM
modeled impact from one large source
modeled Hg(0)
Neuglobsow 1999 (with background)
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3.0
con
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trat
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(n
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measured TGMmodeled TGM
Comparison of measured vs. simulatedtotal gaseous mercury (TGM) at Zingst
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n (n
g/m
3)
modeled Hg(0)modeled Hg(0) + RGMmeasured TGM
Comparison of Modeled vs. Measured TGM: Zingst, 1995
24-Jun-9525-Jun-95
26-Jun-9527-Jun-95
28-Jun-9529-Jun-95
30-Jun-9501-Jul-95
02-Jul-9503-Jul-95
04-Jul-9505-Jul-95
06-Jul-9507-Jul-95
08-Jul-9509-Jul-95
Date
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2.5
concentr
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n (
ng/m
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measured TGM - Zingstmodeled Hg(0) - Zingstmodeled Hg(0) + RGM - Zingst
Comparison of Measured vs. Modeled TGM
Correlation Coefficient = - 0.03
But daily avg conc not too far off…
11/0111/02
11/0311/04
11/0511/06
11/0711/08
11/0911/10
11/1111/12
11/1311/14
11/1511/16
day (1999)
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100
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conc
entr
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n (p
g/m
3)
Measured
Modeled (background = 0)
Modeled (with background)
Comparison of measured vs. simulatedtotal particulate mercury at Zingst
10/2810/29
10/3010/31
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11/0311/04
11/0511/06
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11/0911/10
11/1111/12
11/1311/14
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day (1999)
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(pg/
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Rorvik measured RGM Rorvik modeled RGM
Comparison of measured vs. modeled RGM (comparison for measurement periods only)
• In the first version of the HYSPLIT-Hg model used in this intercomparison, Hg(p) was assumed to be completely converted to dissolved Hg(II) whenever a particle becomes a droplet (e.g., above approximately 80% relative humidity); and dissolved Hg(II) assumed to become Hg(p) whenever the droplet dries out
• Hg(p) and Hg(II) were thus somewhat “equivalent” in the model
• With this assumption, the model tended to underpredict Hg(p) and overpredict Hg(II), suggesting that the assumption of complete conversion was not valid.
• However, it was encouraging to note that the model was getting approximately the right answer for the sum of the two forms of mercury (Hg(p) + Hg(II), representing the total pool of oxidized Hg in the atmosphere [see the following graphs]
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-No
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date
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200
con
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(p
g/m
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modeled RGM + Hg(p)
measured RGM + Hg(p)
NOTE: measurement data are plotted only at times when there were measurements of BOTH RGM and TPM
Comparison of measured vs. modeled RGM + TPM at Mace Head
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-No
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-No
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-No
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date
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100
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con
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(p
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3)
modeled RGM + Hg(p)
measured RGM + Hg(p)
NOTE: measurement data are plotted only at times when there were measurements of BOTH RGM and TPMmodeled data are plotted only at times when there are measurement data
Comparison of measured vs. modeled RGM + TPM at Mace Head
As a result of this observation, the model was re-run with the assumption that Hg(p) was not soluble.
With this assumption, the results for Hg(p) and RGM were dramatically better. [These new results are what have been shown in this presentation, except for the immediately preceding RGM+Hg(p) graphs]
The affect of changing this assumption had a negligible impact on Hg(0), as might be expected, given the generally very low concentrations of Hg(II) and Hg(p) relative to Hg(0).
Some Concluding Notes
The version of HYSPLIT-Hg used for these calculations represented a very early stage of development of the model.
Methodology assumes linear independence of sources; potential advantage that detailed source-receptor relationships can be estimated
The model has been changed significantly since these runs… (hopefully improved!)
It may be useful to reconsider some of the model evaluation metrics
Hg(p) solubility?
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