Difference between revisions of "TransportTracers simulation"

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This page contains information about the Radon-Lead-Beryllium simulation in GEOS-Chem.
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__FORCETOC__
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'''''[[Tagged O3 simulation|Previous]] | [[Guide to GEOS-Chem simulations|Next]] | [[Guide to GEOS-Chem simulations]]'''''
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#[[GEOS-Chem chemistry mechanisms|Simulations using KPP-built mechanisms]]
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#[[Aerosol-only simulation]]
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#[[CH4 simulation]]
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#[[CO2 simulation]]
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#[[Mercury|Hg simulation]]
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#[[POPs simulation]]
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#[[Tagged CO simulation]]
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#[[Tagged O3 simulation]]
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#<span style="color:blue">'''TransportTracers simulation'''</span>
  
== Overview ==
 
  
The Rn-Pb-Be simulation in GEOS-Chem was based on that of the old Harvard/GISS CTM model.  The current simulation follows ''Liu et al'' [2001].
+
This page contains information about the TransportTracers (formerly Rn-Pb-Be) simulation in GEOS-Chem.
  
The standard Rn-Pb-Be simulation uses the following tracers:
+
== Overview ==
  
#Rn<sup>222</sup>, which is emitted naturally from soils
+
The Rn-Pb-Be simulation in GEOS-Chem was based on that of the old Harvard/GISS CTM model. The current simulation follows [http://acmg.seas.harvard.edu/publications/2001/liu2001.pdf Liu et al (2001)]. 
#Pb<sup>210</sup>, which is the primary decay product of Rn<sup>222</sup>
+
#Be<sup>7</sup>, which is produced by cosmic rays in the stratosphere and upper atmosphere
+
  
This simulation is most frequently used to validate the convection and advection processes in GEOS-Chem.
+
In [[GEOS-Chem 12#12.2.0|GEOS-Chem 12.2.0]] the Rn-Pb-Be simulation was extended to include additional passive species for benchmarking purposes and for diagnosing transport in GEOS-Chem. At this time the simulation was renamed to the '''''TransportTracer simulation'''''.  
  
== Sources ==
+
In [[GEOS-Chem 14.2.0]] the TransportTracers simulation was further modified so that species names and definitions are now consistent with GMAO's tracer gridded component (aka TR_GridComp). This will facilitate comparison of transport within GEOS-Chem, GCHP, and GEOS.
  
The source of #Rn<sup>222</sup> is determined as follows (cf. ''Jacob et al'' [1997]):
+
=== List of species ===
  
#Rn<sup>222</sup> emission poleward of 70 degrees = 0.0 [atoms/cm2/s]
+
The transport tracers are summarized below.
#For latitudes 70S-60S and 60N-70N (both land & ocean), Rn<sup>222</sup> emission = 0.005 [atoms/cm2/s]
+
#For latitudes between 60S and 60N:
+
#*Rn<sup>222</sup> over land = 1 [atoms/cm2/s] over land
+
#*Rn<sup>222</sup> over land = 0.005 [atoms/cm2/s] over oceans
+
#Where the surface temperature is below 0&deg; C, reduce Rn<sup>222</sup> emissions by a factor of 3.
+
  
The source of Be<sup>7</sup> is taken from ''Lal and Peters'' [1967].
+
{| border=1 cellspacing=0 cellpadding=5
 +
|-bgcolor="#CCCCCC"
 +
!width="100px"|Species name
 +
!width="200px"|Description
 +
!width="300px"|Source
 +
!width="300px"|Sink
 +
!width="300px"|Purpose
  
== Sinks ==
+
|-valign="top"
 +
|Rn222
 +
|Radon-222 isotope
 +
|
 +
*Emitted naturally from soils based on [https://acp.copernicus.org/articles/21/1861/2021/ Zhang et al., 2021].
 +
|
 +
*Half-life of 3.83 days (Liu at al., 2001).
 +
**Decays into Pb<sup>210</sup> according to the exponential law:
 +
::<tt>EXP( -&Delta;T * 2.097d-6  )</tt>
 +
|Used to evaluate convection over land and strat-trop exchange
  
Rn<sup>222</sup> decays into Pb<sup>210</sup> according to the exponential law: <tt>EXP( -&Delta;T * 2.097d-)</tt>
+
|-valign="top"
 +
|Pb210
 +
|Lead-210 isotope
 +
|
 +
*Radioactive decay from Rn<sup>222</sup> according to the exponential law:
 +
::<tt>EXP( -&Delta;T * 2.097d-6  )</tt>
 +
::Where &Delta;T is the emission timestep in seconds.
 +
|
 +
*Half-life of 22.3 years (Liu et al., 2001).
 +
**Decays according to the exponential law:
 +
::<tt>EXP( -&Delta;T * 9.725d-10 )</tt>
 +
*Wet deposition
 +
*Dry deposition
 +
|Used to evaluate wet scavenging and transport
  
Pb<sup>210</sup> decays according to the exponential law: <tt>EXP( -&Delta;T * 9.725d-10 )</tt>
+
|-valign="top"
 +
|Pb210s
 +
|Lead-210 isotope stratospheric-source tracer
 +
|
 +
*Same as Pb210 (restricted to the stratosphere)
 +
|
 +
*Same as Pb210
 +
|Used to evaluate strat-trop exchange
  
Be<sup>7</sup> decays according to the exponential law: <tt>EXP( -&Delta;T * 1.506d-7  )</tt>
+
|-valign="top"
 +
|Be7
 +
|Beryllium-7 isotope
 +
|
 +
*Produced by cosmic rays as described in [https://link.springer.com/chapter/10.1007/978-3-642-46079-1_7 Lal and B. Peters, 1967]
 +
*Plus the following modifications from Liu et al. (2001):
 +
#Replace data at (0 hPa altitude, 70&deg;S latitude) following Koch (1996):
 +
#*old value = <tt>3000 disintegrations/g air/s</tt>
 +
#*new value = <tt>1900 disintegrations/g air/s</tt>
 +
#The original Lal & Peters data ended at 70&deg;S
 +
#*Copy the data values at 70&deg;S to 80&deg;S and 90&deg;S at all levels
 +
|
 +
*Half-life of 53.3 days (Liu et al., 2001).
 +
**Decays according to the exponential law:
 +
::<tt>EXP( -&Delta;T * 1.506d-7  )</tt>
 +
*Wet deposition
 +
*Dry deposition
 +
|Used to evaluate wet scavenging and strat-trop exchange
  
where -&Delta;T is the emission timestep in seconds.
+
|-valign="top"
 +
|Be7s
 +
|Beryllium-7 isotope stratospheric source tracer
 +
|
 +
*Same as Be7 (restricted to the stratosphere)
 +
|
 +
*Same as Be7
 +
|Used to evaluate strat-trop exchange
  
== Validation ==
+
|-valign="top"
 +
|Be10
 +
|Beryllium-10 isotope
 +
|
 +
*Be<sup>10</sup> has an identical source distribution as Be<sup>7</sup> following Koch and Rind (1998).
 +
|
 +
*Half-life of 5.84e8 days (Koch and Rind, 1998).
 +
**Decays according to the exponential law:
 +
::<tt>EXP( -&Delta;T * 1.506d-7  )</tt>
 +
*Wet deposition
 +
*Dry deposition
 +
|Used to evaluate wet scavenging and strat-trop exchange
  
See ''Liu et al'' [2001].
+
|-valign="top"
 +
|Be10s
 +
|Beryllium-10 isotope stratospheric source tracer
 +
|
 +
*Same as Be10 (restricted to the stratosphere)
 +
|
 +
*Same as Be10
 +
|Used to evaluate strat-trop exchange
  
== References ==
+
|-valign="top"
 +
|PassiveTracer
 +
|Passive tracer with initial concentration of 100 ppb
 +
|
 +
*None
 +
|
 +
*None
 +
|Used to evaluate mass conservation in transport
  
#Liu, H., D. Jacob, I. Bey, and R.M. Yantosca, ''Constraints from 210Pb and 7Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields'', <u>J. Geophys. Res</u>, '''106''', D11, 12,109-12,128, 2001.
+
|-valign="top"
#Jacob et al., ''Evaluation and intercomparison of global atmospheric transport models using Rn-222 and other short-lived tracers'', <u>J. Geophys. Res</u>, '''102''', 5953-5970, 1997.
+
|SF6
#Koch, D. <u>J. Geophys. Res</u>, '''101''', D13, 18651, 1996.
+
|Sulfur hexafluoride
#Lal, D., and B. Peters, ''Cosmic ray produced radioactivity on the Earth''. <u>Handbuch der Physik</u>, '''46/2''', 551-612, edited by K. Sitte, Springer-Verlag, New York, 1967.
+
|
 +
*Anthropogenic emissions from EDGAR v4.2
 +
|
 +
*None
 +
|Used to evaluate inter-hemispheric transport of anthropogenic emissions
  
== Previous issues that are now resolved ==
+
|-valign="top"
 +
|CH3I
 +
|Methyl iodide
 +
|
 +
*Emissions over the oceans of 1 molec/cm2/s
 +
|
 +
*5-day e-folding lifetime
 +
|Used to evaluate marine convection
  
=== Incorrect Rn values caused by bug in convection_mod.f ===
+
|-valign="top"
 +
|CO_25
 +
|Anthropogenic CO 25-day tracer
 +
|
 +
*Emissions from CEDS v2
 +
|
 +
*25-day e-folding lifetime
 +
|
  
[[GEOS-Chem_v8-03-02#TINY_parameter_in_convection_mod.f|The bug in convection_mod.f described here]] can cause incorrect values of Rn in [[GEOS-Chem v8-03-01]] and prior versions.  This was fixed in [[GEOS-Chem v8-03-02]].
+
|-valign="top"
 +
|CO_50
 +
|Anthropogenic CO 50-day tracer
 +
|
 +
*Emissions from CEDS v2
 +
|
 +
*50-day e-folding lifetime
 +
|
  
--[[User:Bmy|Bob Y.]] 16:17, 19 May 2011 (EDT)
+
|-valign="top"
 +
|e90
 +
|Constant burden 90-day tracer
 +
|
 +
*Emitted globally at the surface such that the mixing ratio is maintained at 100 ppbv
 +
|
 +
*90-day e-folding lifetime
 +
|
  
=== Bug for ND44 diagnostic in diag3.f ===
+
|-valign="top"
 +
|e90_n
 +
|Constant burden Northern Hemisphere 90-day tracer
 +
|
 +
*Emitted at the surface such that the mixing ratio is maintained at 100 ppbv. Emissions source is restricted to 40N - 90N.
 +
|
 +
*90-day e-folding lifetime
 +
|
  
'''''NOTE: This bug was issued as a post-release patch ("v9-01-01-Patch-diags") in [[GEOS-Chem v9-01-01]] and was approved on 07 Jun 2011.'''''
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|-valign="top"
 +
|e90_s
 +
|Constant burden Southern Hemisphere 90-day tracer
 +
|
 +
*Emitted at the surface such that the mixing ratio is maintained at 100 ppbv. Emissions source is restricted to 90S - 40S.
 +
|
 +
*90-day e-folding lifetime
 +
|
  
In the ND44 diagnostic section of <tt>diag3.f</tt>, the following lines are present twice (once for drydep fluxes and again for drydep velocities).  This is a special-case for some tracers in the Caltech isoprene scheme:
+
|-valign="top"
 +
|aoa
 +
|Age of air uniform source tracer
 +
|
 +
*Increases by a value of 1 each emissions timestep
 +
|
 +
*Sink at the surface
 +
|Used for evaluating residual circulation and mixing
  
              ! Special case for tracers with several dry dep. tracers
+
|-valign="top"
              ! E.g. ISOPN: ISOPND and ISOPNB.
+
|aoa_bl
              ! We handle both tracers at the same time so we need to  
+
|Age of air uniform source tracer with sink restricted to the boundary layer
              ! skip the second tracer. (ccc, 2/3/10)
+
|
              !IF ( MMB /= NN ) CYCLE
+
*Increases by a value of 1 each emissions timestep
              IF ( MMB /= NN                .OR.
+
|
    &              DEPNAME( N ) == 'ISOPNB' .OR.
+
*Sink in the boundary layer
    &              DEPNAME( N ) == 'MVKN'      ) CYCLE
+
|Used for evaluating residual circulation and mixing
  
However, these lines will cause the drydep fluxes and velocities for Be7 to be skipped.  The fix is to bracket these lines with an IF statement so that they will only execute for a full-chemistry simulation:
+
|-valign="top"
 +
|aoa_nh
 +
|Age of air uniform source tracer with sink restricted to a zone in the Northern Hemisphere
 +
|
 +
*Increases by a value of 1 each emissions timestep
 +
|
 +
*Sink at 30N - 50N
 +
|Used for evaluating residual circulation and mixing
  
            IF ( ITS_A_FULLCHEM_SIM() ) THEN
+
|-valign="top"
              ! Special case for tracers with several dry dep. tracers
+
|nh_5
              ! E.g. ISOPN: ISOPND and ISOPNB.
+
|Northern Hemisphere 5-day tracer
              ! We handle both tracers at the same time so we need to
+
|
              ! skip the second tracer. (ccc, 2/3/10)
+
*Constant source of 100 ppbv at latitudes 30N - 50N
              !IF ( MMB /= NN ) CYCLE
+
|
              IF ( MMB /= NN                .OR.
+
*5-day e-folding lifetime
    &              DEPNAME( N ) == 'ISOPNB' .OR.
+
|
    &              DEPNAME( N ) == 'MVKN'      ) CYCLE
+
            ENDIF
+
  
--[[User:Bmy|Bob Y.]] 11:57, 7 July 2011 (EDT)
+
|-valign="top"
 +
|nh_50
 +
|Northern Hemisphere 50-day tracer
 +
|
 +
*Constant source of 100 ppbv at latitudes 30N - 50N
 +
|
 +
*50-day e-folding lifetime
 +
|
  
== Outstanding issues ==
+
|-valign="top"
 +
|st80_25
 +
|Stratospheric source 25-day tracer
 +
|
 +
*Constant source of 200 ppbv above 80 hPa
 +
|
 +
*25-day e-folding lifetime
 +
|
  
=== Missing drydep diagnostics caused by tracer name error  ===
+
|}
  
Please use the following tracer names in <tt>input.geos</tt> when setting up a Rn-Pb-Be simulation:
+
== References ==
 
+
%%% TRACER MENU %%%    :
+
Type of simulation      : 1
+
Number of Tracers      : 3                     
+
Tracer Entries -------> : TR#  Name  g/mole  Tracer Members; () = emitted
+
Tracer #1              :  1  Rn    222.0 
+
Tracer #2              :  2  Pb    210.0
+
Tracer #3              :  3  Be7      7.0
+
 
+
If you use alternate spellings for the Rn and Pb tracers, such as:
+
 
+
Tracer #1              :  1  Rn222  222.0 
+
Tracer #2              :  2  Pb210  210.0
+
 
+
Then this may cause the dry deposition fluxes and frequencies for Pb<sup>210</sup> not to be printed out.
+
 
+
A fix is forthcoming in [[GEOS-Chem v9-01-02]].
+
 
+
--[[User:Bmy|Bob Y.]] 11:57, 7 July 2011 (EDT)
+
 
+
=== Out-of-bounds errors in ND01, ND02 diagnostics ===
+
 
+
In <tt>RnPbBe_mod.F</tt>, the ND01 (Source of Rn, Pb, Be) and ND02 (Decay of Rn, Pb, Be) diagnostics had [[Common GEOS-Chem error messages#Array-out-of-bounds|array-out-of-bounds errors]] if you requested less than 47 levels. 
+
 
+
For example, if you specified these settings in your <tt>input.geos</tt> file (assuming a GEOS-5 or MERRA simulation  w/ 47 levels):
+
 
+
ND01: Rn/Pb/Be source  : 47  all
+
ND02: Rn/Pb/Be decay    : 47  all
+
 
+
then your run would work just fine.  However, if you tried this:
+
 
+
ND01: Rn/Pb/Be source  :  1  all
+
ND02: Rn/Pb/Be decay    :  1  all
+
 
+
then your run would crash.  In some instances, the error masked itself as an I/O error (i.e. "file not found").  This is because an out-of-bounds was probably corrupting the variables that were used to check if all of the data had been read from a particular met field file.
+
 
+
To prevent this from happening, we now test whether the L index is smaller or equal to LD01 (the vertical extent of the AD01 array) or LD02 (the vertical extent of the AD02 array).  We have now modified all of the IF statements where the ND01 or ND02 diagnostics are invoked. 
+
 
+
For example, we took the existing block of code:
+
 
+
      ! ND01 diag: 7Be emission [kg/s]
+
      IF ( ND01 > 0 ) THEN
+
        AD01(I,J,L,3) = AD01(I,J,L,3) + ( ADD_Be / DTSRCE )
+
      ENDIF
+
 
+
and add an additional test on L:
+
 
+
      ! ND01 diag: 7Be emission [kg/s]
+
      IF ( ND01 > 0 .and. L <= LD01 ) THEN
+
        AD01(I,J,L,3) = AD01(I,J,L,3) + ( ADD_Be / DTSRCE )
+
      ENDIF
+
  
etc.
+
#Liu, H., D. Jacob, I. Bey, and R.M. Yantosca, ''Constraints from <sup>210</sup>Pb and <sup>7</sup>Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields'', <u>J. Geophys. Res</u>, '''106''', D11, 12109-12128, 2001.
 +
#Jacob et al., ''Evaluation and intercomparison of global atmospheric transport models using <sup>222</sup>Rn and other short-lived tracers'', <u>J. Geophys. Res</u>, '''102''', 5953-5970, 1997.
 +
#Koch, D.M., D.J. Jacob, and W.C. Graustein, ''Vertical transport of tropospheric aerosols as indicated by <sup>7</sup>Be and <sup>210</sup>Pb in a chemical tracer model'', <u>J. Geophys. Res</u>, '''101''', D13, 18651-18666, 1996.
 +
#Koch, D., and D. Rind, ''Beryllium 10/beryllium 7 as a tracer of stratospheric transport'', <u>J. Geophys. Res.</u>, '''103''', D4, 3907-3917, 1998.
 +
#Lal, D., and B. Peters, ''Cosmic ray produced radioactivity on the Earth''. <u>Handbuch der Physik</u>, '''46/2''', 551-612, edited by K. Sitte, Springer-Verlag, New York, 1967.
  
We will add this fix into [[GEOS-Chem v9-01-02]], since it does not affect the full-chemistry simulation.
 
  
--[[User:Bmy|Bob Y.]] 16:50, 8 November 2011 (EST)
+
----
 +
'''''[[Tagged O3 simulation|Previous]] | [[Guide to GEOS-Chem simulations|Next]] | [[Guide to GEOS-Chem simulations]]'''''

Latest revision as of 17:18, 24 October 2023

Previous | Next | Guide to GEOS-Chem simulations

  1. Simulations using KPP-built mechanisms
  2. Aerosol-only simulation
  3. CH4 simulation
  4. CO2 simulation
  5. Hg simulation
  6. POPs simulation
  7. Tagged CO simulation
  8. Tagged O3 simulation
  9. TransportTracers simulation


This page contains information about the TransportTracers (formerly Rn-Pb-Be) simulation in GEOS-Chem.

Overview

The Rn-Pb-Be simulation in GEOS-Chem was based on that of the old Harvard/GISS CTM model. The current simulation follows Liu et al (2001).

In GEOS-Chem 12.2.0 the Rn-Pb-Be simulation was extended to include additional passive species for benchmarking purposes and for diagnosing transport in GEOS-Chem. At this time the simulation was renamed to the TransportTracer simulation.

In GEOS-Chem 14.2.0 the TransportTracers simulation was further modified so that species names and definitions are now consistent with GMAO's tracer gridded component (aka TR_GridComp). This will facilitate comparison of transport within GEOS-Chem, GCHP, and GEOS.

List of species

The transport tracers are summarized below.

Species name Description Source Sink Purpose
Rn222 Radon-222 isotope
  • Half-life of 3.83 days (Liu at al., 2001).
    • Decays into Pb210 according to the exponential law:
EXP( -ΔT * 2.097d-6 )
Used to evaluate convection over land and strat-trop exchange
Pb210 Lead-210 isotope
  • Radioactive decay from Rn222 according to the exponential law:
EXP( -ΔT * 2.097d-6 )
Where ΔT is the emission timestep in seconds.
  • Half-life of 22.3 years (Liu et al., 2001).
    • Decays according to the exponential law:
EXP( -ΔT * 9.725d-10 )
  • Wet deposition
  • Dry deposition
Used to evaluate wet scavenging and transport
Pb210s Lead-210 isotope stratospheric-source tracer
  • Same as Pb210 (restricted to the stratosphere)
  • Same as Pb210
Used to evaluate strat-trop exchange
Be7 Beryllium-7 isotope
  • Produced by cosmic rays as described in Lal and B. Peters, 1967
  • Plus the following modifications from Liu et al. (2001):
  1. Replace data at (0 hPa altitude, 70°S latitude) following Koch (1996):
    • old value = 3000 disintegrations/g air/s
    • new value = 1900 disintegrations/g air/s
  2. The original Lal & Peters data ended at 70°S
    • Copy the data values at 70°S to 80°S and 90°S at all levels
  • Half-life of 53.3 days (Liu et al., 2001).
    • Decays according to the exponential law:
EXP( -ΔT * 1.506d-7 )
  • Wet deposition
  • Dry deposition
Used to evaluate wet scavenging and strat-trop exchange
Be7s Beryllium-7 isotope stratospheric source tracer
  • Same as Be7 (restricted to the stratosphere)
  • Same as Be7
Used to evaluate strat-trop exchange
Be10 Beryllium-10 isotope
  • Be10 has an identical source distribution as Be7 following Koch and Rind (1998).
  • Half-life of 5.84e8 days (Koch and Rind, 1998).
    • Decays according to the exponential law:
EXP( -ΔT * 1.506d-7 )
  • Wet deposition
  • Dry deposition
Used to evaluate wet scavenging and strat-trop exchange
Be10s Beryllium-10 isotope stratospheric source tracer
  • Same as Be10 (restricted to the stratosphere)
  • Same as Be10
Used to evaluate strat-trop exchange
PassiveTracer Passive tracer with initial concentration of 100 ppb
  • None
  • None
Used to evaluate mass conservation in transport
SF6 Sulfur hexafluoride
  • Anthropogenic emissions from EDGAR v4.2
  • None
Used to evaluate inter-hemispheric transport of anthropogenic emissions
CH3I Methyl iodide
  • Emissions over the oceans of 1 molec/cm2/s
  • 5-day e-folding lifetime
Used to evaluate marine convection
CO_25 Anthropogenic CO 25-day tracer
  • Emissions from CEDS v2
  • 25-day e-folding lifetime
CO_50 Anthropogenic CO 50-day tracer
  • Emissions from CEDS v2
  • 50-day e-folding lifetime
e90 Constant burden 90-day tracer
  • Emitted globally at the surface such that the mixing ratio is maintained at 100 ppbv
  • 90-day e-folding lifetime
e90_n Constant burden Northern Hemisphere 90-day tracer
  • Emitted at the surface such that the mixing ratio is maintained at 100 ppbv. Emissions source is restricted to 40N - 90N.
  • 90-day e-folding lifetime
e90_s Constant burden Southern Hemisphere 90-day tracer
  • Emitted at the surface such that the mixing ratio is maintained at 100 ppbv. Emissions source is restricted to 90S - 40S.
  • 90-day e-folding lifetime
aoa Age of air uniform source tracer
  • Increases by a value of 1 each emissions timestep
  • Sink at the surface
Used for evaluating residual circulation and mixing
aoa_bl Age of air uniform source tracer with sink restricted to the boundary layer
  • Increases by a value of 1 each emissions timestep
  • Sink in the boundary layer
Used for evaluating residual circulation and mixing
aoa_nh Age of air uniform source tracer with sink restricted to a zone in the Northern Hemisphere
  • Increases by a value of 1 each emissions timestep
  • Sink at 30N - 50N
Used for evaluating residual circulation and mixing
nh_5 Northern Hemisphere 5-day tracer
  • Constant source of 100 ppbv at latitudes 30N - 50N
  • 5-day e-folding lifetime
nh_50 Northern Hemisphere 50-day tracer
  • Constant source of 100 ppbv at latitudes 30N - 50N
  • 50-day e-folding lifetime
st80_25 Stratospheric source 25-day tracer
  • Constant source of 200 ppbv above 80 hPa
  • 25-day e-folding lifetime

References

  1. Liu, H., D. Jacob, I. Bey, and R.M. Yantosca, Constraints from 210Pb and 7Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields, J. Geophys. Res, 106, D11, 12109-12128, 2001.
  2. Jacob et al., Evaluation and intercomparison of global atmospheric transport models using 222Rn and other short-lived tracers, J. Geophys. Res, 102, 5953-5970, 1997.
  3. Koch, D.M., D.J. Jacob, and W.C. Graustein, Vertical transport of tropospheric aerosols as indicated by 7Be and 210Pb in a chemical tracer model, J. Geophys. Res, 101, D13, 18651-18666, 1996.
  4. Koch, D., and D. Rind, Beryllium 10/beryllium 7 as a tracer of stratospheric transport, J. Geophys. Res., 103, D4, 3907-3917, 1998.
  5. Lal, D., and B. Peters, Cosmic ray produced radioactivity on the Earth. Handbuch der Physik, 46/2, 551-612, edited by K. Sitte, Springer-Verlag, New York, 1967.



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