Dear ARTS users,
I am writing to address a question with the use of OEM in the ARTS development
version.
From the "TestOEM.arts" in "ARTS/controlfiles/artscomponents/oem", this time I
changed the codes as follows.
1) From (line 115):
retrievalAddAbsSpecies(
species = "O3",
unit = "vmr",
g1 = p_ret_grid,
g2 = lat_grid,
g3 = lon_grid
)
To:
retrievalAddTemperature (
g1 = p_ret_grid,
g2 = lat_grid,
g3 = lon_grid,
hse = "off" )
2) From (line 125):
VectorSetConstant(vars, nelem, 1e-12)
DiagonalMatrix(sparse_block, vars)
covmat_sxAddBlock(block = sparse_block)
To:
VectorSetConstant(vars, nelem, 0.1)
DiagonalMatrix(sparse_block, vars)
covmat_sxAddBlock(block = sparse_block)
3) From (line 37):
NumericSet( f_start, 110.436e9 )
NumericSet( f_end, 111.236e9 )
IndexSet( nf, 801 )
IndexSet( np, 81 )
To:
NumericSet( f_start, 110.436e9 )
NumericSet( f_end, 111.236e9 )
IndexSet( nf, 18 )
IndexSet( np, 18 )
4) From (line 42):
VectorNLinSpace( f_grid, nf, f_start, f_end )
VectorNLogSpace( p_grid, 361, 500e2, 0.1 )
VectorNLogSpace( p_ret_grid, np, 500e2, 0.1 )
To:
VectorNLinSpace( f_grid, nf, f_start, f_end )
VectorNLogSpace( p_grid, 18, 500e2, 0.1 )
VectorNLogSpace( p_ret_grid, np, 500e2, 0.1 )
Overall, I changed the ozone VMR retrieval to temperature retrieval and reduced
the number of frequencies and pressure layers.
When I run the controlfile multiple times, I irregularly get errors. The error
messages are
Run-time error in oem computation: Forward Model Evaluation Error
Run-time error in agenda: inversion_iterate_agenda
Run-time error in method: atmfields_checkedCalc
The variable *t_field* contains one or several NaNs. This is not allowed!
or
All temperatures in *t_field* must be > 0.
or seldom the bad partition function warning.
Here are my questions:
1) Is this an anticipated error, simply coming from failing to find a
converging solution? Is it expected that the OEM sometimes throws an error as
above?
2) Are there mechanisms (e.g. workspace methods) within the ARTS that can
prevent the t_field or vmr_field from becoming either negative or NaN during
the OEM iterations?
Thank you for your assistance.
Regards,
Byungsuk Lee
ARA Consulting & Technology
30 Songdomirae-ro D-1510, Yeonsu-gu, Incheon 21990, South Korea
Email: cb...@aracnt.com
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