TransportTracers simulation

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1. Simulations using KPP-built mechanisms (carbon, fullchem, Hg)
2. Aerosol-only simulation
3. CH4 simulation
4. CO2 simulation
5. Metals simulation
6. Hg simulation
7. POPs simulation
8. Tagged CO simulation
9. Tagged O3 simulation
10. 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	Emitted naturally from soils based on Zhang et al., 2021.	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): 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 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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