Questions for other users and developers can be posted on the RTTOV Forum.
| Frequently Asked Questions: |
- Do I need to bother to upgrade my version of RTTOV-93 to
RTTOV-10?
If you want any of the following the answer is yes (if you have v7 or v8 there are more reasons) :- Improved clear air transmittance simulations for all gases due to improved underlying spectroscopy from LBLRTMv11.1 and coefficient files now on 51L
- Improved version of FASTEM for microwave sea surface emissivity
- Provision of land surface emissivity atlases for IR and MW
- Ability to simulate 2 cloud types in one layer
- Ability to compute principal components of IASI and AIRS spectra
- Inclusion of Zeeman effect for high peaking microwave channels (ie AMSU-A and SSMIS)
- Improved microwave scattering code
- Can I compile the code in single precision to save space?
Yes the precision of the variables are defined by the src/main/parkind.F90 module. This file needs to be edited to change the precision using the JPRB variable. Note however that running the adjoint models (AD and K) in single precision can result in significant errors in the output. - I don't have an ozone or CO2 , CO, N2O, CH4 or cloud liquid
water profile to include in the state vector. What can I do?
You can either make sure you have a coefficient file which includes the above in the mixed gases (apart from CLW) which is the case for most coefficient files anyway or you can still use a coefficient file with minor gas coefficients and the reference profile supplied with the coefficients is used. You must take care to set the logical flags for example profiles(1) % co_data etc to false if you don't have a CO profile. If you don't the program assumes you are providing a valid profile and will fail if you don't. - My profile top is below the top level required by RTTOV-10, how
do I best extrapolate it for RTTOV?
If you use the internal interpolation routines of RTTOV-10 to take the user supplied levels and put them on the RTTOV coefficient file levels then this will be done for you though at a cost in CPU. If you don't want to use the internal interpolation and supply a profile on the coeff levels then for gas concentrations it is best to use the reference profile for levels above the user input which is available by the coef structure e.g. for water vapour coef%ref_prfl_mr(:,coef%fmv_gas_pos(gas_id_watervapour)) For temperature one can extrapolate from the top level of the users profile using a representative lapse rate from standard atmospheres. - Why does the new emissivity atlas code cause compilation
errors?
This code requires the NetCDF library in order to compile. Make sure that you edit the file build/Makefile.local to point to the location of your NetCDF installation before you build the code. - Why do some of the tests fail when I compile with ifort?
You should increase the stack size by executing:
$ ulimit -s unlimited
before running the test scripts.