Difference between revisions of "TransportTracers simulation"

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(Known issues)
(Known issues)
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=== Incorrect Rn values caused by bug in convection_mod.f ===
 
=== Incorrect Rn values caused by bug in convection_mod.f ===
  
[[GEOS-Chem_v8-03-02#TINY_parameter_in_convection_mod.f|The in convection_mod.f described here]] can cause incorrect values of Rn in [[GEOS-Chem v8-03-01]] and prior versions.
+
[[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.
  
 
--[[User:Bmy|Bob Y.]] 16:17, 19 May 2011 (EDT)
 
--[[User:Bmy|Bob Y.]] 16:17, 19 May 2011 (EDT)

Revision as of 20:17, 19 May 2011

This page contains information about the Radon-Lead-Beryllium 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].

The standard Rn-Pb-Be simulation uses the following tracers:

  1. Rn222, which is emitted naturally from soils
  2. Pb210, which is the primary decay product of Rn222
  3. Be7, 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.

Sources

The source of #Rn222 is determined as follows (cf. Jacob et al [1997]):

  1. Rn222 emission poleward of 70 degrees = 0.0 [atoms/cm2/s]
  2. For latitudes 70S-60S and 60N-70N (both land & ocean), Rn222 emission = 0.005 [atoms/cm2/s]
  3. For latitudes between 60S and 60N:
    • Rn222 over land = 1 [atoms/cm2/s] over land
    • Rn222 over land = 0.005 [atoms/cm2/s] over oceans
  4. Where the surface temperature is below 0° C, reduce Rn222 emissions by a factor of 3.

The source of Be7 is taken from Lal and Peters [1967].

Sinks

Rn222 decays into Pb210 according to the exponential law: EXP( -ΔT * 2.097d-6 )

Pb210 decays according to the exponential law: EXP( -ΔT * 9.725d-10 )

Be7 decays according to the exponential law: EXP( -ΔT * 1.506d-7 )

where -ΔT is the emission timestep in seconds.

Validation

See Liu et al [2001].

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, 12,109-12,128, 2001.
  2. Jacob et al., Evaluation and intercomparison of global atmospheric transport models using Rn-222 and other short-lived tracers, J. Geophys. Res, 102, 5953-5970, 1997.
  3. Koch, D. J. Geophys. Res, 101, D13, 18651, 1996.
  4. 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.

Known issues

Incorrect Rn values caused by bug 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.

--Bob Y. 16:17, 19 May 2011 (EDT)