Sea salt aerosols
From Geos-chem
Contents
Updates to sea salt emissions algorithm
= Updated hygroscopic
Please see the dis GEOS-Chem_v8-02-04#Updated_hygroscopic_growth_factors_for_sea-salt
Bug fixes in seasalt_mod.f
Please see [[this discussion
Modification of size bins for coarse mode aerosols
Lyatt Jaeglé (jaegle@atmos.washington.edu) wrote:
- I think that we should change the dry size bins for the coarse mode aerosols in input.geos. Instead of using:
Online SEASALT AEROSOLS : T => SALA radius bin [um]: 0.1 0.5 => SALC radius bin [um]: 0.5 10.0
- we should use a smaller upper cut for the dry radius of the coarse mode aerosols (up to 4 microns dry size ==> 8-10 microns radius for wet sea salt).
Online SEASALT AEROSOLS : T => SALA radius bin [um]: 0.1 0.5 => SALC radius bin [um]: 0.5 4.0
- The first two changes lead to a factor of 2 decrease in total sea-salt emissions (from ~8000 Tg/yr to ~4300 Tg/yr using GEOS-4 winds for 2003 2x2.5). The last change leads to another reduction by 40% in emissions. However the total burden of sea-salt aerosols (~12.5 Tg) remains nearly unchanged compared to the old formulation (~13.7 Tg) because of the strong non-linearity of the dry deposition velocity at sizes > 2 microns. Indeed the lifetime of coarse mode sea-salt aerosols (0.5-4um vs 0.5-10um) increases by a factor of almost 3.
- Here is a summary of the changes:
Old formulation in GEOS-Chem (2x2.5 GEOS-4 winds 2003)
0.1-0.5 um | 0.5-10 um | Total: 0.1-10 um | |
---|---|---|---|
Emissions (Tg/yr) | 106 | 7865 | 7970 |
Dry deposition (Tg/yr) | 4.7 | 5012 | 5016 |
Wet deposition (Tg/yr) | 102 | 2859 | 2955 |
Burden (Tg) | 0.73 | 13.01 | 13.74 |
Lifetime (hours) | 60 | 14 | 15 |
0.1-0.5 um | 0.5-10 um | Total: 0.1-10 um
--Bob Y. 10:49, 23 November 2009 (EST) Double-substitution bug in routine GET_ALKBecky Alexander (beckya@u.washington.edu) wrote:
|
---------------------------------- | SO2 uptake onto fine particles | ---------------------------------- | calculate gas-to-particle rate constant for uptake of | SO2 onto fine sea-salt aerosols [Jacob, 2000] analytical solution
CONST1 = 4.D0/(V*GAMMA_SO2) A1 = (RAD1/DG)+CONST1 B1 = (RAD2/DG)+CONST1 |
----------------------------------------------------------------------------- | Prior to 7/18/08: | Becky Alexander's fix to remove double-substitution (bec, bmy, 7/18/08) | Remove these lines: | TERM1A = (((B1/DG)**2)+(2.0D0*CONST1*B1/DG)+(CONST1**2)) - | & (((A1/DG)**2)+(2.0D0*CONST1*A1/DG)+(CONST1**2)) | TERM2A = 2.D0*CONST1*(((B1/DG)+CONST1)-((A1/DG)+CONST1)) | TERM3A = (CONST1**2)*(LOG((B1/DG)+CONST1) - | & LOG((A1/DG)+CONST1)) | KT1 = 4.D0*PI*N1*(DG**2)*(TERM1A - TERM2A + TERM3A) | -----------------------------------------------------------------------------
TERM1A = ((B1**2)/2.0d0) - (((A1**2)/2.0d0) TERM2A = 2.D0*CONST1*(B1-A1) TERM3A = (CONST1**2)*LOG(B1/A1) KT1 = 4.D0*PI*N1*(DG**3)*(TERM1A - TERM2A + TERM3A) |
---------------------------------- | SO2 uptake onto coarse particles | ---------------------------------- | calculate gas-to-particle rate constant for uptake of | SO2 onto coarse sea-salt aerosols [Jacob, 2000] analytical solution
CONST2 = 4.D0/(V*GAMMA_SO2) A2 = (RAD2/DG)+CONST2 B2 = (RAD3/DG)+CONST2 |
------------------------------------------------------------------------------ | Prior to 7/18/08: | Becky Alexander's fix to remove double-substitution (bec, bmy, 7/18/08) | Remove these lines: | TERM1B = (((B2/DG)**2)+(2.0D0*CONST2*B2/DG)+(CONST2**2)) - | & (((A2/DG)**2)+(2.0D0*CONST2*A2/DG)+(CONST2**2)) | TERM2B = 2.D0*CONST2*(((B2/DG)+CONST2)-((A2/DG)+CONST2)) | TERM3B = (CONST2**2)*(LOG((B2/DG)+CONST2) - | & LOG((A2/DG)+CONST2)) | KT2 = 4.D0*PI*N2*(DG**2)*(TERM1B - TERM2B + TERM3B) | ------------------------------------------------------------------------------
TERM1B = ((B2**2)/2.0d0) - (((A2**2)/2.0d0) TERM2B = 2.D0*CONST2*(B2-A2) TERM3B = (CONST2**2)*LOG(B2/A2) KT2 = 4.D0*PI*N2*(DG**3)*(TERM1B - TERM2B + TERM3B) KT = KT1 + KT2 |
---------------------------------- | HNO3 uptake onto fine particles | ---------------------------------- | calculate gas-to-particle rate constant for uptake of | HNO3 onto fine sea-salt aerosols [Jacob, 2000] analytical solution
CONST1N = 4.D0/(V*GAMMA_HNO3) A1N = (RAD1/DG)+CONST1N B1N = (RAD2/DG)+CONST1N |
----------------------------------------------------------------------------- | Prior to 7/18/08: | Becky Alexander's fix to remove double-substitution (bec, bmy, 7/18/08) | Remove these lines: | TERM1AN = (((B1N/DG)**2)+(2.0D0*CONST1N*B1N/DG)+(CONST1N**2)) - | & (((A1N/DG)**2)+(2.0D0*CONST1N*A1N/DG)+(CONST1N**2)) | TERM2AN = 2.D0*CONST1N*(((B1N/DG)+CONST1N)-((A1N/DG)+CONST1N)) | TERM3AN = (CONST1N**2)*(LOG((B1N/DG)+CONST1N) - | & LOG((A1N/DG)+CONST1N)) | KT1N = 4.D0*PI*N1*(DG**2)*(TERM1AN - TERM2AN + TERM3AN) | -----------------------------------------------------------------------------
TERM1AN = ((B1N**2)/2.0d0) - (((A1N**2)/2.0d0) TERM2AN = 2.D0*CONST1N*(B1N-A1N) TERM3AN = (CONST1N**2)*LOG(B1N/A1N) KT1N = 4.D0*PI*N1*(DG**3)*(TERM1AN - TERM2AN + TERM3AN) |
---------------------------------- | HNO3 uptake onto coarse particles | ---------------------------------- | calculate gas-to-particle rate constant for uptake of | HNO3 onto coarse sea-salt aerosols [Jacob, 2000] analytical solution
CONST2N = 4.D0/(V*GAMMA_HNO3) A2N = (RAD2/DG)+CONST2N B2N = (RAD3/DG)+CONST2N |
----------------------------------------------------------------------------- | Prior to 7/18/08: | Becky Alexander's fix to remove double-substitution (bec, bmy, 7/18/08) | Remove these lines: | TERM1BN = (((B2N/DG)**2)+(2.0D0*CONST2N*B2N/DG)+(CONST2N**2)) - | & (((A2N/DG)**2)+(2.0D0*CONST2N*A2N/DG)+(CONST2N**2)) | TERM2BN = 2.D0*CONST2N*(((B2N/DG)+CONST2N)-((A2N/DG)+CONST2N)) | TERM3BN = (CONST2N**2)*(LOG((B2N/DG)+CONST2N) - | & LOG((A2N/DG)+CONST2N)) | KT2N = 4.D0*PI*N2*(DG**2)*(TERM1BN - TERM2BN + TERM3BN) | -----------------------------------------------------------------------------
TERM1BN = ((B2N**2)/2.0d0) - (((A2N**2)/2.0d0) TERM2BN = 2.D0*CONST2N*(B2N-A2N) TERM3BN = (CONST2N**2)*LOG(B2N/A2N) KT2N = 4.D0*PI*N2*(DG**3)*(TERM1BN - TERM2BN + TERM3BN) Please make the fix in your version, or you may download it from ftp://ftp.as.harvard.edu/pub/geos-chem/patches/v8-01-01/seasalt_mod.f_w_getalk_fix. Also see this document by Becky Alexander which describes the analytical solution in more detail. Duncan Fairlie (t.d.fairlie@nasa.gov) replied:
Kt = 4.pi.N.D(cubed)[ ] ,
dr = D.dx,
( r=[a,b] )
X = [a/D+c, b/D+c]
NOTE: This fix has been incorporated into GEOS-Chem v8-01-02. --Bob Y. 16:15, 7 August 2008 (EDT) |
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